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Kusmartsev F, Zhang B, Liu Y, Luo Y, Vincent-Ward J, Alkallas F, Ben Gouider Trabelsi A, Kusmartseva A. Rashba Metamaterials and Metasurfaces with Zero Reflectivity and Effect of Surface States in Ultrathin Metal Films. ACS Appl Mater Interfaces 2024; 16:4904-4917. [PMID: 38232238 PMCID: PMC10835661 DOI: 10.1021/acsami.3c15285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
Metals, renowned for their high reflectivity, find extensive use in various technological applications, from mirrors to optical coatings in radars, telescopes, and mobile communications. However, their potential in antireflective coatings has remained largely untapped. In this study, we demonstrate that by applying an ultrathin metallic film onto an oxide layer, we can achieve a flawless optical surface with zero reflectivity. This phenomenon has been successfully observed across various metals, including Sn, Ag, Au, Pt, Bi, and Nb, showcasing its broad applicability. The underlying principle lies in the emergence of surface states, where the Rashba effect is strong, which give rise to the formation of Rashba metamaterial and metasurface (RMM) structures. Remarkably, these RMMs can be fine-tuned to act as high-resolution Veselago lenses. To illustrate, we achieved zero reflectivity with an RMM consisting of a 1 nm thick Sn metal film on a 1 nm Ge buffer, situated on a 60 nm Al2O3/Si substrate. Similar results were observed for other metals (Pt, Au, Ag, and Nb) and semimetals (Bi) by adjusting the film thickness to 2, 3, 5, 10, and 6 nm, respectively. The revelation of RMMs with zero reflectivity (R = 0) has tremendous potential to revolutionize optical device technologies, covering renewable energy, optoelectronics, and the telecommunications industry.
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Affiliation(s)
- Fedor Kusmartsev
- College of Engineering and Physical Sciences, Khalifa University, P.O. Box 127788 Abu Dhabi 51133, United Arab Emirates
- Microsystem and Terahertz Research Center, Chengdu 610200, P. R. China
- Department of Physics, Loughborough University, Loughborough LE11 3TU, U.K
| | - Binglei Zhang
- Microsystem and Terahertz Research Center, Chengdu 610200, P. R. China
| | - Yang Liu
- Microsystem and Terahertz Research Center, Chengdu 610200, P. R. China
| | - Yi Luo
- Microsystem and Terahertz Research Center, Chengdu 610200, P. R. China
| | - James Vincent-Ward
- Department of Physics, Loughborough University, Loughborough LE11 3TU, U.K
| | - Fatemah Alkallas
- Department of Physics, College of Science, Princess Nourah Bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia
| | - Amira Ben Gouider Trabelsi
- Department of Physics, College of Science, Princess Nourah Bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia
| | - Anna Kusmartseva
- Department of Physics, Loughborough University, Loughborough LE11 3TU, U.K
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2
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Llusar J, du Fossé I, Hens Z, Houtepen A, Infante I. Surface Reconstructions in II-VI Quantum Dots. ACS Nano 2024; 18:1563-1572. [PMID: 38169474 PMCID: PMC10795476 DOI: 10.1021/acsnano.3c09265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 12/20/2023] [Accepted: 12/22/2023] [Indexed: 01/05/2024]
Abstract
Although density functional theory (DFT) calculations have been crucial in our understanding of colloidal quantum dots (QDs), simulations are commonly carried out on QD models that are significantly smaller than those generally found experimentally. While smaller models allow for efficient study of local surface configurations, increasing the size of the QD model will increase the size or number of facets, which can in turn influence the energetics and characteristics of trap formation. Moreover, core-shell structures can only be studied with QD models that are large enough to accommodate the different layers with the correct thickness. Here, we use DFT calculations to study the electronic properties of QDs as a function of size, up to a diameter of ∼4.5 nm. We show that increasing the size of QD models traditionally used in DFT studies leads to a disappearance of the band gap and localization of the HOMO and LUMO levels on facet-specific regions of the QD surface. We attribute this to the lateral coupling of surface orbitals and the formation of surface bands. The introduction of surface vacancies and their a posteriori refilling with Z-type ligands leads to surface reconstructions that widen the band gap and delocalize both the HOMO and LUMO. These results show that the surface geometry of the facets plays a pivotal role in defining the electronic properties of the QD.
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Affiliation(s)
- Jordi Llusar
- BCMaterials,
Basque Center for Materials, Applications, and Nanostructures, UPV/EHU Science Park, Leioa 48940, Spain
| | - Indy du Fossé
- Department
of Chemical Engineering, Optoelectronic Materials, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The
Netherlands
| | - Zeger Hens
- Physics
and Chemistry of Nanostructures, Department of Chemistry, and Center
of Nano and Biophotonics, Ghent University, B-9000 Gent, Belgium
| | - Arjan Houtepen
- Department
of Chemical Engineering, Optoelectronic Materials, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The
Netherlands
| | - Ivan Infante
- BCMaterials,
Basque Center for Materials, Applications, and Nanostructures, UPV/EHU Science Park, Leioa 48940, Spain
- Ikerbasque
Basque Foundation for Science, Bilbao 48009, Spain
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3
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Koroteev YM, Silkin IV, Silkin VM, Chulkov EV. Quantum-Size Effects in Ultra-Thin Gold Films on Pt(111) Surface. Materials (Basel) 2023; 17:63. [PMID: 38203917 PMCID: PMC10779727 DOI: 10.3390/ma17010063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 12/15/2023] [Accepted: 12/19/2023] [Indexed: 01/12/2024]
Abstract
We calculate, within the density-functional theory, the atomic and electronic structure of the clean Pt(111) and Au(111) surfaces and the nML-Au/Pt(111) systems with n varying from one to three. The effect of the spin-orbital interaction was taken into account. Several new electronic states with strong localization in the surface region were found and discussed in the case of clean surfaces. The Au adlayers introduce numerous quantum well states in the energy regions corresponding to the projected bulk band continuum of Au(111). Moreover, the presence of states resembling the true Au(111) surface states can be detected at n = 2 and 3. The Au/Pd interface states are found as well. In nML-Au/Pt(111), the calculated work function presents a small variation with a variation of the number of the Au atomic layer. Nevertheless, the effect is significantly smaller in comparison to the s-p metals.
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Affiliation(s)
- Yury M. Koroteev
- Institute of Strength Physics and Materials Science, Siberian Branch of Russian Academy of Sciences, 634055 Tomsk, Russia
- Laboratory of Electronic and Spin Structure of Nanosystems, Saint Petersburg State University, 198504 Saint Petersburg, Russia
| | - Igor V. Silkin
- Faculty of Physics, Tomsk State University, 634050 Tomsk, Russia
| | - Vyacheslav M. Silkin
- Departamento de Polímeros y Materiales Avanzados: Física, Química y Tecnología, Facultad de Ciencias Químicas, Universidad del País Vasco (UPV-EHU), Apdo. 1072, 20080 San Sebastián, Spain
- Donostia International Physics Center (DIPC), P. Manuel Lardizabal 4, 20018 San Sebastián, Spain
- IKERBASQUE, Basque Foundation for Science, Pl. Euskadi 5, 48009 Bilbao, Spain
| | - Evgueni V. Chulkov
- Laboratory of Electronic and Spin Structure of Nanosystems, Saint Petersburg State University, 198504 Saint Petersburg, Russia
- Departamento de Polímeros y Materiales Avanzados: Física, Química y Tecnología, Facultad de Ciencias Químicas, Universidad del País Vasco (UPV-EHU), Apdo. 1072, 20080 San Sebastián, Spain
- Donostia International Physics Center (DIPC), P. Manuel Lardizabal 4, 20018 San Sebastián, Spain
- Centro de Física de Materiales (CFM-MPC), Centro Mixto CSIC-UPV/EHU, P. Manuel Lardizabal 5, 20018 San Sebastián, Spain
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4
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Rastogi G, Mohapatra A, Mishra P, Mandal S, Kulkarni R, Ganesan R, Thamizhavel A, Anil Kumar PS. Crossover from gapped-to-gapless Dirac surface states in magnetic topological insulator MnBi 2Te 4. J Phys Condens Matter 2023; 36:085703. [PMID: 37883988 DOI: 10.1088/1361-648x/ad0765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 10/26/2023] [Indexed: 10/28/2023]
Abstract
Intrinsic magnetic topological insulators (MTIs) host exotic topological phases such as quantized anomalous Hall insulating phase, arising due to the large magnetic exchange gap. However, the interplay of magnetism and topology in these systems in different temperature regimes remains elusive. In this work, we present the logarithmic temperature-dependence of conductivity for sub-100 nm thick exfoliated flakes of MTI MnBi2Te4in the presence of out-of-plane magnetic fields and extracted the linear slope,κ. We observed a characteristic change,Δκ∼-0.5in the low-temperature regime, indicating the gapped Dirac surface state according to Lu-Shen theory. We also report the recovery of topological properties in the system via the weak-antilocalization effect in the vicinity of antiferromagnetic to paramagnetic transition and in the paramagnetic regime. Hikami-Larkin-Nagaoka analysis suggested the presence of topological surface states. Therefore, our study helps in understanding how intrinsic magnetism masks topological properties in an MTI as long as magnetic ordering persists.
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Affiliation(s)
- Gagan Rastogi
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Abhinab Mohapatra
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Pramita Mishra
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Shoubhik Mandal
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - Ruta Kulkarni
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
| | - R Ganesan
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
| | - A Thamizhavel
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
| | - P S Anil Kumar
- Department of Physics, Indian Institute of Science, Bangalore 560012, India
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5
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Ragonese P, Kalinic B, Franco L, Girardi L, Fernández Peréz BM, Carbonera D, Mattei G, Rizzi GA, Maurizio C. Effect of Interfacial SiO x Defects on the Functional Properties of Si-Transition Metal Oxide Photoanodes for Water Splitting. ACS Appl Mater Interfaces 2023; 15:46933-46940. [PMID: 37782757 PMCID: PMC10571009 DOI: 10.1021/acsami.3c09555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 09/19/2023] [Indexed: 10/04/2023]
Abstract
The transfer of photogenerated charges through interfaces in heterojunction photoanodes is a key process that controls the efficiency of solar water splitting. Considering Co3O4/SiOx/Si photoanodes prepared by physical vapor deposition as a representative case study, it is shown that defects normally present in the native SiOx layer dramatically affect the onset of the photocurrent. Electron paramagnetic resonance indicates that the signal of defects located in dangling bonds of trivalent Si atoms at the Si/SiOx interface vanishes upon vacuum annealing at 850 °C. Correspondingly, the photovoltage of the photoanode increases to ≈500 mV. Similar results are obtained for NiO/SiOx/Si photoanodes. Photoelectrochemical analysis and impedance spectroscopy (in solution and in the solid state) indicate how the defect annealing modifies the Co3O4/SiOx/Si junction. This work shows that defect annealing at the solid-solid interface in composite photoanodes strongly improves the efficiency of charge transfer through interfaces, which is the basis for effective solar-to-chemical energy conversion.
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Affiliation(s)
- P. Ragonese
- Physics
and Astronomy Department, University of
Padova, Via Marzolo 8, Padova I-35131, Italy
| | - B. Kalinic
- Physics
and Astronomy Department, University of
Padova, Via Marzolo 8, Padova I-35131, Italy
| | - L. Franco
- Department
of Chemical Sciences, University of Padova, Via Marzolo 1, Padova I-35131, Italy
| | - L. Girardi
- Department
of Chemical Sciences, University of Padova, Via Marzolo 1, Padova I-35131, Italy
| | - B. M. Fernández Peréz
- Physics
and Astronomy Department, University of
Padova, Via Marzolo 8, Padova I-35131, Italy
| | - D. Carbonera
- Department
of Chemical Sciences, University of Padova, Via Marzolo 1, Padova I-35131, Italy
| | - G. Mattei
- Physics
and Astronomy Department, University of
Padova, Via Marzolo 8, Padova I-35131, Italy
| | - G.-A. Rizzi
- Department
of Chemical Sciences, University of Padova, Via Marzolo 1, Padova I-35131, Italy
| | - C. Maurizio
- Physics
and Astronomy Department, University of
Padova, Via Marzolo 8, Padova I-35131, Italy
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6
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Zeng X, Zhao C, Jiang X, Yu R, Che R. Functional Tailoring of Multi-Dimensional Pure MXene Nanostructures for Significantly Accelerated Electromagnetic Wave Absorption. Small 2023; 19:e2303393. [PMID: 37291740 DOI: 10.1002/smll.202303393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Revised: 05/21/2023] [Indexed: 06/10/2023]
Abstract
Transition metal carbide (Ti3 C2 Tx MXene), with a large specific surface area and abundant surface functional groups, is a promising candidate in the family of electromagnetic wave (EMW) absorption. However, the high conductivity of MXene limits its EMW absorption ability, so it remains a challenge to obtain outstanding EMW attenuation ability in pure MXene. Herein, by integrating HF etching, KOH shearing, and high-temperature molten salt strategies, layered MXene (L-MXene), network-like MXene nanoribbons (N-MXene NRs), porous MXene monolayer (P-MXene ML), and porous MXene layer (P-MXene L) are rationally constructed with favorable microstructures and surface states for EMW absorption. HF, KOH, and KCl/LiCl are used to functionalize MXene to tune its microstructure and surface state (F- , OH- , and Cl- terminals), thereby improving the EMW absorption capacity of MXene-based nanostructures. Impressively, with the unique structure, proper electrical conductivity, large specific surface area, and abundant porous defects, MXene-based nanostructures achieve good impedance matching, dipole polarization, and conduction loss, thus inheriting excellent EMW absorption performance. Consequently, L-MXene, N-MXene NRs, P-MXene ML, and P-MXene L enable a reflection loss (RL ) value of -43.14, -63.01, -60.45, and -56.50 dB with a matching thickness of 0.95, 1.51, 3.83, and 4.65 mm, respectively.
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Affiliation(s)
- Xiaojun Zeng
- Advanced Ceramic Materials Research Institute, School of Materials Science and Engineering, Jingdezhen Ceramic University, Jingdezhen, 333403, China
| | - Chao Zhao
- Advanced Ceramic Materials Research Institute, School of Materials Science and Engineering, Jingdezhen Ceramic University, Jingdezhen, 333403, China
| | - Xiao Jiang
- Advanced Ceramic Materials Research Institute, School of Materials Science and Engineering, Jingdezhen Ceramic University, Jingdezhen, 333403, China
| | - Ronghai Yu
- School of Materials Science and Engineering, Beihang University, Beijing, 100191, China
| | - Renchao Che
- Laboratory of Advanced Materials, Shanghai Key Lab of Molecular Catalysis and Innovative Materials, Department of Materials Science, Fudan University, Shanghai, 200438, China
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7
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Alcántara Ortigoza M, Rahman TS. A closer look at how symmetry constraints and the spin-orbit coupling shape the electronic structure of Bi(111). J Phys Condens Matter 2023; 36:015503. [PMID: 37726010 DOI: 10.1088/1361-648x/acfb67] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 09/19/2023] [Indexed: 09/21/2023]
Abstract
Fully relativistic density-functional-theory calculations of Bi(111) thin films are analyzed to revisit their two metallic surface-states branches. We first contrast these metallic branches with surface states arising at gaps in the valence band opened by the spin-orbit coupling (SOC). We find that the two metallic branches alongΓM‾do not overlap with the bulk band at the zone boundary,M. We show that the spin texture observed in such states cannot be traced to the lifting of Kramers' degeneracy. Instead, we track them to themj=±1/2-mj=±3/2SOC splitting, the potential anisotropy for in-plane and out-of-plane states, and the coupling between the opposite surfaces of a slab occurring nearM, which is driven by a spatial redistribution of the four metallic states composing the two metallic branches. Each of these branches appears to be non-degenerate at the tested surface, yet each is degenerate with another state of opposite spin at the other surface. Nevertheless, the four metallic states bear some contribution on both surfaces of the film because of their spatial redistribution nearM. The overlapping among these states nearM, afforded by their spatial redistribution on both surfaces, causes a hybridization that perpetuates the splitting between the two branches, makes the film's electronic structure thickness dependent nearM, extinguishes the magnetic moment of the metallic states avoiding the magnetic-moment discontinuity atM, and denies the need or expectancy of the metallic branches becoming degenerate atM. We propose that theoppositespin polarization observed for the two metallic branches occurs because the surface atoms retain their covalent bonds and thus cannot afford magnetic polarization. We show that the Rashba-splitting of the metallic states for inversion-asymmetric films does not have a fixed magnitude but can be tuned by changing the perturbation breaking inversion symmetry.
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Affiliation(s)
- Marisol Alcántara Ortigoza
- Department of Physics, Tuskegee University, Tuskegee Institute, Tuskegee, AL 36088, United States of America
| | - Talat S Rahman
- Department of Physics, University of Central Florida, Orlando, FL 32816, United States of America
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8
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Mazzola F, Enzner S, Eck P, Bigi C, Jugovac M, Cojocariu I, Feyer V, Shu Z, Pierantozzi GM, De Vita A, Carrara P, Fujii J, King PDC, Vinai G, Orgiani P, Cacho C, Watson MD, Rossi G, Vobornik I, Kong T, Di Sante D, Sangiovanni G, Panaccione G. Observation of Termination-Dependent Topological Connectivity in a Magnetic Weyl Kagome Lattice. Nano Lett 2023; 23:8035-8042. [PMID: 37638737 PMCID: PMC10510577 DOI: 10.1021/acs.nanolett.3c02022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 08/21/2023] [Indexed: 08/29/2023]
Abstract
Engineering surfaces and interfaces of materials promises great potential in the field of heterostructures and quantum matter designers, with the opportunity to drive new many-body phases that are absent in the bulk compounds. Here, we focus on the magnetic Weyl kagome system Co3Sn2S2 and show how for the terminations of different samples the Weyl points connect differently, still preserving the bulk-boundary correspondence. Scanning tunneling microscopy has suggested such a scenario indirectly, and here, we probe the Fermiology of Co3Sn2S2 directly, by linking it to its real space surface distribution. By combining micro-ARPES and first-principles calculations, we measure the energy-momentum spectra and the Fermi surfaces of Co3Sn2S2 for different surface terminations and show the existence of topological features depending on the top-layer electronic environment. Our work helps to define a route for controlling bulk-derived topological properties by means of surface electrostatic potentials, offering a methodology for using Weyl kagome metals in responsive magnetic spintronics.
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Affiliation(s)
- Federico Mazzola
- Department
of Molecular Sciences and Nanosystems, Ca’
Foscari University of Venice, 30172 Venice, Italy
| | - Stefan Enzner
- Institut
für Theoretische Physik und Astrophysik and Würzburg-Dresden
Cluster of Excellence ct.qmat, Universität
Würzburg, 97074 Würzburg, Germany
| | - Philipp Eck
- Institut
für Theoretische Physik und Astrophysik and Würzburg-Dresden
Cluster of Excellence ct.qmat, Universität
Würzburg, 97074 Würzburg, Germany
| | - Chiara Bigi
- School
of Physics and Astronomy, University of
St Andrews, St Andrews KY16 9SS, United
Kingdom
| | - Matteo Jugovac
- Elettra
Sincrotrone Trieste S.C.p.A. S. S. 14, km 163.5, 34149 Trieste, Italy
| | - Iulia Cojocariu
- Elettra
Sincrotrone Trieste S.C.p.A. S. S. 14, km 163.5, 34149 Trieste, Italy
- Università degli studi di Trieste Via A. Valerio 2, 34127 Trieste, Italy
| | - Vitaliy Feyer
- Forschungszentrum Juelich GmBH PGI-6Leo Brandt Strasse, 52425 Juelich, Germany
| | - Zhixue Shu
- Department
of Physics, University of Arizona, Tucson, Arizona 85721, United States
| | - Gian Marco Pierantozzi
- Istituto
Officina dei Materiali, Consiglio Nazionale
delle Ricerche, Trieste I-34149, Italy
| | - Alessandro De Vita
- Dipartimento
di Fisica Universitá di Milano, Via Celoria 16, Milano 20133, Italy
| | - Pietro Carrara
- Dipartimento
di Fisica Universitá di Milano, Via Celoria 16, Milano 20133, Italy
| | - Jun Fujii
- Istituto
Officina dei Materiali, Consiglio Nazionale
delle Ricerche, Trieste I-34149, Italy
| | - Phil D. C. King
- School
of Physics and Astronomy, University of
St Andrews, St Andrews KY16 9SS, United
Kingdom
| | - Giovanni Vinai
- Istituto
Officina dei Materiali, Consiglio Nazionale
delle Ricerche, Trieste I-34149, Italy
| | - Pasquale Orgiani
- Istituto
Officina dei Materiali, Consiglio Nazionale
delle Ricerche, Trieste I-34149, Italy
| | - Cephise Cacho
- Diamond
Light
Source, Harwell Campus, Didcot OX11 0DE, United Kingdom
| | - Matthew D. Watson
- Diamond
Light
Source, Harwell Campus, Didcot OX11 0DE, United Kingdom
| | - Giorgio Rossi
- Dipartimento
di Fisica Universitá di Milano, Via Celoria 16, Milano 20133, Italy
| | - Ivana Vobornik
- Istituto
Officina dei Materiali, Consiglio Nazionale
delle Ricerche, Trieste I-34149, Italy
| | - Tai Kong
- Department
of Physics, University of Arizona, Tucson, Arizona 85721, United States
| | - Domenico Di Sante
- Department
of Physics and Astronomy, University of
Bologna, 40127 Bologna, Italy
- Center
for Computational Quantum Physics, Flatiron
Institute, 162 5th Avenue, New York, New York 10010, United States
| | - Giorgio Sangiovanni
- Institut
für Theoretische Physik und Astrophysik and Würzburg-Dresden
Cluster of Excellence ct.qmat, Universität
Würzburg, 97074 Würzburg, Germany
| | - Giancarlo Panaccione
- Istituto
Officina dei Materiali, Consiglio Nazionale
delle Ricerche, Trieste I-34149, Italy
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9
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Gao L, Chai H, Niu H, Jin J, Ma J. Roles of Cobalt-Coordinated Polymeric Perylene Diimide in Hematite Photoanodes for Improved Water Oxidation. Small 2023; 19:e2302665. [PMID: 37264749 DOI: 10.1002/smll.202302665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 05/11/2023] [Indexed: 06/03/2023]
Abstract
Interfacial charge recombination is a permanent issue that impedes the photon energy utilization in photoelectrochemical (PEC) water splitting. Herein, a conjugated polymer, urea linked perylene diimide polymer (PDI), is introduced to the designation of hematite-based composite photoanodes. On account of its unique molecule structure with abundant electronegative atoms, the O and N atoms with lone electron pairs can bond with Fe atoms at the surface of Zr4+ doped α-Fe2 O3 (Zr:Fe2 O3 ) and thus establish charge transfer channels for expediting hole separation and migration. Meanwhile, PDI molecules can passivate the surface states in Zr:Fe2 O3 , which is in favor of suppressing carrier recombination. Particularly, Co2+ is used to coordinate with PDI (Co-PDI) to accelerate hole extraction as well as utilization, and the as-obtained Co-PDI form type-II heterojunction with Zr:Fe2 O3 . Such a photoanode configuration takes advantage of the unique molecule structure of PDI, and the target Co-PDI/Zr:Fe2 O3 photoanodes eventually attain a photocurrent density of 2.17 mA cm-2 , which is inspirational for unearthing the potential use of conjugative molecules in PEC fields.
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Affiliation(s)
- Lili Gao
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), The Key Laboratory of Catalytic Engineering of Gansu Province, Key Laboratory of Advanced Catalysis of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, P. R. China
| | - Huan Chai
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), The Key Laboratory of Catalytic Engineering of Gansu Province, Key Laboratory of Advanced Catalysis of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, P. R. China
| | - Huilin Niu
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), The Key Laboratory of Catalytic Engineering of Gansu Province, Key Laboratory of Advanced Catalysis of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, P. R. China
| | - Jun Jin
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), The Key Laboratory of Catalytic Engineering of Gansu Province, Key Laboratory of Advanced Catalysis of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, P. R. China
| | - Jiantai Ma
- State Key Laboratory of Applied Organic Chemistry (SKLAOC), The Key Laboratory of Catalytic Engineering of Gansu Province, Key Laboratory of Advanced Catalysis of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, P. R. China
- School of Chemical Engineering and Technology, Tianshui Normal University, Tianshui, Gansu, 741001, P. R. China
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10
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Chen M, Hu L, Xu L, Wei J, Wu P, Guan G, Wang T, Ma Y. Synergistically Tuning Surface States of Hierarchical MoC by Pt-N Dual-Doping Engineering for Optimizing Hydrogen Evolution Activity. Small Methods 2023; 7:e2300308. [PMID: 37154229 DOI: 10.1002/smtd.202300308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 04/21/2023] [Indexed: 05/10/2023]
Abstract
Catalytic performance can be greatly enhanced by rational modulation of the surface state. In this study, reasonable adjustment of the surface states around the Fermi level (EF ) of molybdenum carbide (MoC) (α phase) via a Pt-N dual-doping process to fabricate an electrocatalyst named as Pt-N-MoC is performed to promote hydrogen evolution reaction (HER) performance over the MoC surface. Systematically experimental and theoretical analyses demonstrate that the synergistic tuning of Pt and N can cause the delocalization of surface states, with an increase in the density of surface states near the EF . This is beneficial for accumulating and transferring electrons between the catalyst surface and adsorbent, resulting in a positively linear correlation between the density of surface states near the EF and the HER activity. Moreover, the catalytic performance is further enhanced by artificially fabricating a Pt-N-MoC catalyst that has a unique hierarchical structure composed of MoC nanoparticles (0D), nanosheets (2D), and microrods (3D). As expected, the obtained Pt-N-MoC electrocatalyst exhibits superb HER activity with an extremely low overpotential of 39 mV@10 mA cm-2 as well as superb stability (over 24 d) in an alkaline solution. This work highlights a novel strategy to develop efficient electrocatalysts via adjusting their surface states.
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Affiliation(s)
- Meng Chen
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006, China
- Graduate School of Science and Technology, Hirosaki University, Hirosaki, 036-8561, Japan
| | - Lihua Hu
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006, China
| | - Li Xu
- Novel Energy Materials & Catalysis Research Center, Shanwei Institute of Technology, Shanwei, 516600, China
| | - Junling Wei
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006, China
| | - Ping Wu
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Guoqing Guan
- Graduate School of Science and Technology, Hirosaki University, Hirosaki, 036-8561, Japan
- Energy Conversion Engineering Laboratory, Institute of Regional Innovation (IRI), Hirosaki University, Hirosaki, 036-8561, Japan
| | - Tiejun Wang
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006, China
| | - Yufei Ma
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006, China
- College of Chemistry and Material Science, Hebei Normal University, Shijiazhuang, 050024, China
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11
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Qu S, Wu H, Ng YH. Thin Zinc Oxide Layer Passivating Bismuth Vanadate for Selective Photoelectrochemical Water Oxidation to Hydrogen Peroxide. Small 2023; 19:e2300347. [PMID: 37026677 DOI: 10.1002/smll.202300347] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 02/28/2023] [Indexed: 06/19/2023]
Abstract
Selective photoelectrochemical (PEC) water oxidation to hydrogen peroxide is an underexplored option as opposed to the mainstream oxygen reduction reaction. Albeit interesting, selective H2 O2 production via oxidative pathway is plagued by the noncontrollable two-electron transfer reaction and the overoxidation of the thus-formed H2 O2 to O2 . Here, ZnO passivator-coated BiVO4 photoanode is reported for selective PEC H2 O2 production. Both the H2 O2 selectivity and production rate increase in the range of 1.0-2.0 V versus RHE under simulated sunlight irradiation. The photoelectrochemical impedance spectra and open-circuit potentials suggest a flattened band bending and positively shifted quasi-Fermi level of BiVO4 upon ZnO coating, facilitating H2 O2 generation and suppressing the competitive reaction of O2 evolution. The ZnO overlayer also inhibits H2 O2 decomposition, accelerates charge extraction from BiVO4 , and serves as a hole reservoir under photoexcitation. This work offers insights into surface states and the role of the coating layer in manipulating two/four-electron transfer for selective H2 O2 synthesis from PEC water oxidation.
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Affiliation(s)
- Songying Qu
- Low-Carbon and Climate Impact Research Centre, School of Energy and Environment, City University of Hong Kong, Kowloon, 999077, Hong Kong S.A.R
| | - Hao Wu
- Macao Institute of Materials Science and Engineering (MIMSE), Faculty of Innovation Engineering, Macau University of Science and Technology, Taipa, 999078, Macau SAR
| | - Yun Hau Ng
- Low-Carbon and Climate Impact Research Centre, School of Energy and Environment, City University of Hong Kong, Kowloon, 999077, Hong Kong S.A.R
- School of Energy and Environment, City University of Hong Kong Shenzhen Research Institute, Shenzhen Hi-Tech Industrial Park, Nanshan District, Shenzhen, 518000, China
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12
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Brzozowski E, Kaminski M, Taube A, Sadowski O, Krol K, Guziewicz M. Carrier Trap Density Reduction at SiO 2/4H-Silicon Carbide Interface with Annealing Processes in Phosphoryl Chloride and Nitride Oxide Atmospheres. Materials (Basel) 2023; 16:4381. [PMID: 37374564 DOI: 10.3390/ma16124381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 06/02/2023] [Accepted: 06/07/2023] [Indexed: 06/29/2023]
Abstract
The electrical and physical properties of the SiC/SiO2 interfaces are critical for the reliability and performance of SiC-based MOSFETs. Optimizing the oxidation and post-oxidation processes is the most promising method of improving oxide quality, channel mobility, and thus the series resistance of the MOSFET. In this work, we analyze the effects of the POCl3 annealing and NO annealing processes on the electrical properties of metal-oxide-semiconductor (MOS) devices formed on 4H-SiC (0001). It is shown that combined annealing processes can result in both low interface trap density (Dit), which is crucial for oxide application in SiC power electronics, and high dielectric breakdown voltage comparable with those obtained via thermal oxidation in pure O2. Comparative results of non-annealed, NO-annealed, and POCl3-annealed oxide-semiconductor structures are shown. POCl3 annealing reduces the interface state density more effectively than the well-established NO annealing processes. The result of 2 × 1011 cm-2 for the interface trap density was attained for a sequence of the two-step annealing process in POCl3 and next in NO atmospheres. The obtained values Dit are comparable to the best results for the SiO2/4H-SiC structures recognized in the literature, while the dielectric critical field was measured at a level ≥9 MVcm-1 with low leakage currents at high fields. Dielectrics, which were developed in this study, have been used to fabricate the 4H-SiC MOSFET transistors successfully.
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Affiliation(s)
- Ernest Brzozowski
- Łukasiewicz Research Network-Institute of Microelectronics and Photonics, Al. Lotników 32/46, 02-668 Warsaw, Poland
| | - Maciej Kaminski
- Łukasiewicz Research Network-Institute of Microelectronics and Photonics, Al. Lotników 32/46, 02-668 Warsaw, Poland
- Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, Ul. Koszykowa 75, 00-662 Warsaw, Poland
| | - Andrzej Taube
- Łukasiewicz Research Network-Institute of Microelectronics and Photonics, Al. Lotników 32/46, 02-668 Warsaw, Poland
| | - Oskar Sadowski
- Łukasiewicz Research Network-Institute of Microelectronics and Photonics, Al. Lotników 32/46, 02-668 Warsaw, Poland
- Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, Ul. Koszykowa 75, 00-662 Warsaw, Poland
| | - Krystian Krol
- Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, Ul. Koszykowa 75, 00-662 Warsaw, Poland
| | - Marek Guziewicz
- Łukasiewicz Research Network-Institute of Microelectronics and Photonics, Al. Lotników 32/46, 02-668 Warsaw, Poland
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13
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Hou S, Gao X, Wang S, Yu X, Liao J, Su D. Precise Defect Engineering on Graphitic Carbon Nitrides for Boosted Solar H 2 Production. Small 2023:e2302500. [PMID: 37259673 DOI: 10.1002/smll.202302500] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 05/08/2023] [Indexed: 06/02/2023]
Abstract
Defect engineering has been regarded as an "all-in-one strategy" to alleviate the insufficient solar utilization in g-C3 N4 . However, without appropriate modification, the defect benefits will be partly offset due to the formation of deep localized defect states and deteriorated surface states, lowering the photocarrier separation efficiency. To this end, the defective g-C3 N4 is designed with both S dopants and N vacancies via a dual-solvent-assisted synthetic approach. The precise defect control is realized by the addition of ethylene glycol (EG) into precursor formation and molten sulfur into the pyrolysis process, which simultaneously induced g-C3N4. with shallow defect states. These shallow defect energy levels can act as a temporary electron reservoir, which are critical to evoke the migrated electrons from CB with a moderate trapping ability, thus suppressing the bulky photocarrier recombination. Additionally, the optimized surface states of DCN-ES are also demonstrated by the highest electron-trapping resistance (Rtrapping ) of 9.56 × 103 Ω cm2 and the slowest decay kinetics of surface carriers (0.057 s-1 ), which guaranteed the smooth surface charge transfer rather than being the recombination sites. As a result, DCN-ES exhibited a superior H2 evolution rate of 4219.9 µmol g-1 h-1 , which is 29.1-fold higher than unmodified g-C3 N4 .
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Affiliation(s)
- Shaoqi Hou
- School of Mathematical and Physical Sciences, Faculty of Science, University of Technology Sydney, Broadway, NSW, 2007, Australia
| | - Xiaochun Gao
- School of Physics and Optoelectronic Engineering, Ludong University, Yantai, 264000, China
| | - Shijian Wang
- School of Mathematical and Physical Sciences, Faculty of Science, University of Technology Sydney, Broadway, NSW, 2007, Australia
| | - Xingxing Yu
- School of Mathematical and Physical Sciences, Faculty of Science, University of Technology Sydney, Broadway, NSW, 2007, Australia
- Department of Chemistry, The University of Tokyo, Tokyo, 7-3-1 Hogo, Bunkyo, Japan
| | - Jiayan Liao
- School of Mathematical and Physical Sciences, Faculty of Science, University of Technology Sydney, Broadway, NSW, 2007, Australia
| | - Dawei Su
- School of Mathematical and Physical Sciences, Faculty of Science, University of Technology Sydney, Broadway, NSW, 2007, Australia
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Stanescu S, Alun T, Dappe YJ, Ihiawakrim D, Ersen O, Stanescu D. Enhancement of the Solar Water Splitting Efficiency Mediated by Surface Segregation in Ti-Doped Hematite Nanorods. ACS Appl Mater Interfaces 2023. [PMID: 37219355 DOI: 10.1021/acsami.3c02131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Band engineering is employed thoroughly and targets technologically scalable photoanodes for solar water splitting applications. Complex and costly recipes are necessary, often for average performances. Here, we report simple photoanode growth and thermal annealing with effective band engineering results. By comparing Ti-doped hematite photoanodes annealed under nitrogen to photoanodes annealed in air, we found a strongly enhanced photocurrent of more than 200% in the first case. Using electrochemical impedance spectroscopy and synchrotron X-ray spectromicroscopy, we demonstrate that oxidized surface states and increased density of charge carriers are responsible for the enhanced photoelectrochemical (PEC) activity. Surface states are found to be related to the formation of pseudo-brookite clusters by surface Ti segregation. Spectro-ptychography is used for the first time at the Ti L3 absorption edge to isolate Ti chemical coordination arising from pseudo-brookite cluster contribution. Correlated with electron microscopy investigation and density functional theory calculations, the synchrotron spectromicroscopy data unambiguously prove the origin of enhanced PEC activity of N2-annealed Ti-doped hematite nanorods. Finally, we present here a handy and cheap surface engineering method beyond the known oxygen vacancy doping, allowing a net gain in the PEC activity for the hematite-based photoanodes.
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Affiliation(s)
- Stefan Stanescu
- Synchrotron SOLEIL, L'Orme des Merisiers, Départementale 128, 91190 Saint-Aubin, France
| | - Théo Alun
- SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191 Gif-sur-Yvette Cedex, France
| | - Yannick J Dappe
- SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191 Gif-sur-Yvette Cedex, France
| | - Dris Ihiawakrim
- Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), CNRS UMR 7504, 23 Rue du Loess, BP43, 67034 Strasbourg, France
| | - Ovidiu Ersen
- Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), CNRS UMR 7504, 23 Rue du Loess, BP43, 67034 Strasbourg, France
| | - Dana Stanescu
- SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191 Gif-sur-Yvette Cedex, France
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15
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Qiao Y, Wu S, Zheng Y, Wang C, Li Z, Zhang Y, Zhu S, Jiang H, Cui Z, Liu X. Enhancing Microwave Dynamic Effects via Surface States of Ultrasmall 2D MOF Triggered by Interface Confinement for Antibiotics-Free Therapy. Adv Sci (Weinh) 2023:e2300084. [PMID: 37203263 PMCID: PMC10375132 DOI: 10.1002/advs.202300084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 02/23/2023] [Indexed: 05/20/2023]
Abstract
Microwave (MV)-trigged dynamic therapy based on MV-responsive materials is promising for treating deep infection diseases that cannot be effectively treated by antibiotics, like life-threatening osteomyelitis. Surface states of materials affect the generation of free charges under the excitation source with energy less than the band gap, consequently influencing the MV dynamic effects. Herein, an MV responsive system with interface confined 2D metal-organic framework (2D MOF) on oxidized carbon nanotube (CNT) is prepared, in which the ultrasmall Cu-based 2D MOF possesses sufficient surface/interface defects, endowing the system a large number of surface states. Under MV irradiation, the synthesized CNT-2D MOF not only efficiently absorbs and converts the microwave into heat for microwaveocaloric therapy (MCT) via enhanced hetero-interfacial polarization, but also generates excited electrons via surface state for microwave dynamic therapy (MDT). This biocompatible CNT-2D MOF exhibits highly effective broad-spectrum antimicrobial activity against seven pathogenic bacteria, including Gram-negative and Gram-positive pathogens, under 7 min MV irradiation. And this system is proven to efficiently eradicate Staphylococcus aureus infected rabbit tibia osteomyelitis. Significantly, MV-excited MCT and MDT of CNT-CuHHTP developed in this study makes a major step forward in antibiotic-free MV therapy in deep tissue bacterial infection diseases.
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Affiliation(s)
- Yuqian Qiao
- School of Materials Science and Engineering, Peking University, Beijing, 100871, P. R. China
| | - Shuilin Wu
- School of Materials Science and Engineering, Peking University, Beijing, 100871, P. R. China
| | - Yufeng Zheng
- School of Materials Science and Engineering, Peking University, Beijing, 100871, P. R. China
| | - Chaofeng Wang
- School of Health Science and Biomedical Engineering, Hebei University of Technology, Xiping Avenue 5340, Beichen District, Tianjin, 300401, P. R. China
- Biomedical Materials Engineering Research Center, Hubei Key Laboratory of Polymer Materials, Ministry-of-Education Key Laboratory for the Green Preparation and Application of Functional Materials, School of Materials Science and Engineering, Hubei University, Wuhan, 430062, P. R. China
| | - Zhaoyang Li
- School of Materials Science and Engineering, The Key Laboratory of Advanced Ceramics and Machining Technology by the Ministry of Education of China, Tianjin University, Tianjin, 300072, P. R. China
| | - Yu Zhang
- Department of Orthopedics, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, 510080, P. R. China
| | - Shengli Zhu
- School of Materials Science and Engineering, The Key Laboratory of Advanced Ceramics and Machining Technology by the Ministry of Education of China, Tianjin University, Tianjin, 300072, P. R. China
| | - Hui Jiang
- School of Materials Science and Engineering, The Key Laboratory of Advanced Ceramics and Machining Technology by the Ministry of Education of China, Tianjin University, Tianjin, 300072, P. R. China
| | - Zhenduo Cui
- School of Materials Science and Engineering, The Key Laboratory of Advanced Ceramics and Machining Technology by the Ministry of Education of China, Tianjin University, Tianjin, 300072, P. R. China
| | - Xiangmei Liu
- School of Health Science and Biomedical Engineering, Hebei University of Technology, Xiping Avenue 5340, Beichen District, Tianjin, 300401, P. R. China
- Biomedical Materials Engineering Research Center, Hubei Key Laboratory of Polymer Materials, Ministry-of-Education Key Laboratory for the Green Preparation and Application of Functional Materials, School of Materials Science and Engineering, Hubei University, Wuhan, 430062, P. R. China
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16
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Zhou H, Zhang D, Xie H, Liu Y, Meng C, Zhang P, Fan F, Li R, Li C. Modulating Oxygen Vacancies in Lead Chromate for Photoelectrocatalytic Water Splitting. Adv Mater 2023:e2300914. [PMID: 37038704 DOI: 10.1002/adma.202300914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/16/2023] [Indexed: 06/03/2023]
Abstract
Although modulating oxygen vacancies in semiconductors has attracted broad interest in photocatalysis and photoelectrocatalysis, identifying the intrinsic roles of oxygen vacancies on photoelectrocatalytic properties is often elusive. In this work, the oxygen vacancies in a typical semiconductor lead chromate (PbCrO4 ) are regulated via controlling the oxygen chemical potentials of O-poor and O-rich post-annealing atmospheres. Oxygen vacancies identified in PbCrO4 can introduce electronically shallow energy levels and deep energy levels owing to the symmetry difference of oxygen atoms in the structure. A higher population of deep energy levels created under O-poor atmosphere induces the formation of more surface trapped states, resulting in a higher photovoltage for charge separation. Meanwhile, the existence of surface trapped states can significantly improve the charge injection efficiency of the PbCrO4 photoanode and enhance the water oxidation activity. By modulating oxygen vacancies in the PbCrO4 photoanode, a photocurrent density of 3.43 mA cm-2 at 1.23 V vs reversible hydrogen electrode (RHE) under simulated AM1.5G is acheived. Further passivation of surface trapped states and introducing the water oxidation cocatalyst CoPi lead to a record applied bias photon-to-current efficiency (ABPE) of 1.12%. This work provides a guide to understand the mechanism of oxygen vacancies in oxide-based semiconductor photocatalysis and photoelectrocatalysis.
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Affiliation(s)
- Hongpeng Zhou
- State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian, 116023, P. R. China
| | - Deyun Zhang
- State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian, 116023, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, 100049, Beijing, P. R. China
| | - Huichen Xie
- State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian, 116023, P. R. China
| | - Yang Liu
- School of Materials Science and Engineering (MSE), Ningbo Tech University, No. 1 South Qianhu Road, Ningbo, 315211, P. R. China
| | - Caixia Meng
- State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian, 116023, P. R. China
| | - Pengfei Zhang
- State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian, 116023, P. R. China
| | - Fengtao Fan
- State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian, 116023, P. R. China
| | - Rengui Li
- State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian, 116023, P. R. China
| | - Can Li
- State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian, 116023, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, 100049, Beijing, P. R. China
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Olejnik A, Kopec W, Maskowicz D, Sawczak M. Spin-Resolved Band Structure of Hoffman Clathrate [Fe(pz) 2Pt(CN) 4] as an Essential Tool to Predict Optical Spectra of Metal-Organic Frameworks. ACS Appl Mater Interfaces 2023; 15:15848-15862. [PMID: 36929712 DOI: 10.1021/acsami.2c22626] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Paramount spin-crossover properties of the 3D-Hoffman metalorganic framework (MOF) [Fe(pz)2Pt(CN)4] are generally described on the basis of the ligand field theory, which provides adequate insight into theoretical and simulation analysis of spintronic complexes. However, the ligand field approximation does not take into account the 3D periodicity of the actual complex lattice and surface effects and therefore cannot predict a full-scale periodic structure without utilizing more advanced methods. Therefore, in this paper, the electronic properties of the exemplar MOF were analyzed from the band structure perspective in low-spin (LS) and high-spin (HS) states. The density-of-states spectra determined for both spin-up and spin-down electrons of Fe d6 orbitals indicate spin-orbital splitting and delocalization for HS due to spin polarization in the iron atom ligand field. Presence of the surface states in the real crystal causes a red shift of the metal-metal charge transfer (MMCT) and metal-ligand charge transfer (MLCT) peaks for both HS and LS states. The addition of residual water molecules and disorder among the pyrazine rings reveal additional influences on the positions of the pyrazine band and, therefore, on the absorption spectra of the crystal. The results show a magnification of the peak correlated with the MLCT in the HS state and a significant red shift of the LS characteristic absorption band. The presented approach involving band structure analysis delivers a more complete image of the electronic properties of the [Fe(pz)2Pt(CN)4] crystalline network and can be a landmark for insightful studies of other MOFs.
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Affiliation(s)
- Adrian Olejnik
- Faculty of Electronics, Telecommunications and Informatics, Gdansk University of Technology, 11/12 G. Narutowicza Street, 80-233 Gdansk, Poland
- Centre for Plasma and Laser Engineering, The Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14 Street, 80-231 Gdańsk, Poland
| | - Wioletta Kopec
- Centre for Plasma and Laser Engineering, The Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14 Street, 80-231 Gdańsk, Poland
| | - Dominik Maskowicz
- Centre for Plasma and Laser Engineering, The Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14 Street, 80-231 Gdańsk, Poland
| | - Mirosław Sawczak
- Centre for Plasma and Laser Engineering, The Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14 Street, 80-231 Gdańsk, Poland
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18
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Basak S, Ptok A. Theoretical Study of Dynamical and Electronic Properties of Noncentrosymmetric Superconductor NbReSi. Materials (Basel) 2022; 16:78. [PMID: 36614417 PMCID: PMC9820956 DOI: 10.3390/ma16010078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 12/11/2022] [Accepted: 12/16/2022] [Indexed: 06/17/2023]
Abstract
The noncentrosymmetric NbReSi superconductor with Tc≃6.5 K is characterized by the relatively large upper critical magnetic field. Its multigap features were observed experimentally. Recent studies suggested the realization of P6¯2m or Ima2 symmetry. We discuss the dynamical properties of both symmetries (e.g., phonon spectra). In this paper, using the ab initio techniques, we clarify this ambiguity, and conclude that the Ima2 symmetry is unstable, and P6¯2m should be realized. The P6¯2m symmetry is also stable in the presence of external hydrostatic pressure. We show that NbReSi with the P6¯2m symmetry should host phonon surface states for (100) and (110) surfaces. Additionally, we discuss the main electronic properties of the system with the stable symmetry.
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Ekanayaka TK, Richmond D, McCormick M, Nandyala SR, Helfrich HC, Sinitskii A, Pikal JM, Ilie CC, Dowben PA, Yost AJ. Surface Versus Bulk State Transitions in Inkjet-Printed All-Inorganic Perovskite Quantum Dot Films. Nanomaterials (Basel) 2022; 12:3956. [PMID: 36432242 PMCID: PMC9697151 DOI: 10.3390/nano12223956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 11/05/2022] [Accepted: 11/08/2022] [Indexed: 06/16/2023]
Abstract
The anion exchange of the halides, Br and I, is demonstrated through the direct mixing of two pure perovskite quantum dot solutions, CsPbBr3 and CsPbI3, and is shown to be both facile and result in a completely alloyed single phase mixed halide perovskite. Anion exchange is also observed in an interlayer printing method utilizing the pure, unalloyed perovskite solutions and a commercial inkjet printer. The halide exchange was confirmed by optical absorption spectroscopy, photoluminescent spectroscopy, X-ray diffraction, and X-ray photoemission spectroscopy characterization and indicates that alloying is thermodynamically favorable, while the formation of a clustered alloy is not favored. Additionally, a surface-to-bulk photoemission core level transition is observed for the Cs 4d photoemission feature, which indicates that the electronic structure of the surface is different from the bulk. Time resolved photoluminescence spectroscopy indicates the presence of multiple excitonic decay features, which is argued to originate from states residing at surface and bulk environments.
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Affiliation(s)
- Thilini K. Ekanayaka
- Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - Dylan Richmond
- Department of Physics, State University of New York-Oswego, Oswego, NY 13126, USA
| | - Mason McCormick
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA
| | - Shashank R. Nandyala
- Department of Electrical and Computer Engineering, University of Wyoming, Laramie, WY 82071, USA
| | - Halle C. Helfrich
- Department of Physics, Oklahoma State University, Stillwater, OK 74078, USA
- Department of Physics, Pittsburg State University, Pittsburg, KS 66762, USA
| | - Alexander Sinitskii
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA
| | - Jon M. Pikal
- Department of Electrical and Computer Engineering, University of Wyoming, Laramie, WY 82071, USA
| | - Carolina C. Ilie
- Department of Physics, State University of New York-Oswego, Oswego, NY 13126, USA
| | - Peter A. Dowben
- Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - Andrew J. Yost
- Department of Physics, Oklahoma State University, Stillwater, OK 74078, USA
- Oklahoma Photovoltaic Research Institute, Oklahoma State University, Stillwater, OK 74078, USA
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20
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Zhu H, Tong G, Li J, Xu E, Tao X, Sheng Y, Tang J, Jiang Y. Enriched-Bromine Surface State for Stable Sky-Blue Spectrum Perovskite QLEDs With an EQE of 14.6. Adv Mater 2022; 34:e2205092. [PMID: 35906787 DOI: 10.1002/adma.202205092] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2022] [Revised: 07/25/2022] [Indexed: 06/15/2023]
Abstract
Halogen vacancies are of great concern in blue-emitting perovskite quantum-dot light-emitting diodes because they affect their efficiency and spectral shift. Here, an enriched-bromine surface state is realized using a facile strategy that employs a PbBr2 stock solution for anion exchange based on Cd-doped perovskite quantum dots. It is found that the doped Cd ions are expected to reduce the formation energy of halogen vacancies filled by the external bromine ions, and the excess free bromine ions in solution are enriched in the surface by anchoring with halogen vacancies as sites, accompanied with the shedding of surface long-chain ligands during the anion exchange process, resulting in a Br-rich and "neat" surface. Moreover, the surface state exhibits good passivation of the surface defects of the controlled perovskite QDs and simultaneously increases the exciton binding energy, leading to excellent optical properties and stability. Finally, the sky-blue emitting perovskite quantum-dot light-emitting diodes (QLEDs) (490 nm) are conducted with a record external quantum efficiency of 14.6% and current efficiency of 19.9 cd A-1 . Meanwhile, the electroluminescence spectra exhibit great stability with negligible shifts under a constant operating voltage from 3 to 7 V. This strategy paves the way for improving the efficiency and stability of perovskite QLEDs.
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Affiliation(s)
- Hanwen Zhu
- School of Materials Science and Engineering, Hefei University of Technology, Hefei, 230009, P. R. China
| | - Guoqing Tong
- School of Materials Science and Engineering, Hefei University of Technology, Hefei, 230009, P. R. China
| | - Junchun Li
- School of Materials Science and Engineering, Hefei University of Technology, Hefei, 230009, P. R. China
| | - Enze Xu
- School of Materials Science and Engineering, Hefei University of Technology, Hefei, 230009, P. R. China
| | - Xuyong Tao
- School of Materials Science and Engineering, Hefei University of Technology, Hefei, 230009, P. R. China
| | - Yuanyuan Sheng
- School of Materials Science and Engineering, Hefei University of Technology, Hefei, 230009, P. R. China
| | - Jianxin Tang
- Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, Suzhou, 215123, P. R. China
| | - Yang Jiang
- School of Materials Science and Engineering, Hefei University of Technology, Hefei, 230009, P. R. China
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21
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Mao N, Li R, Dai Y, Huang B, Yan B, Niu C. Orbital Shift-Induced Boundary Obstructed Topological Materials with a Large Energy Gap. Adv Sci (Weinh) 2022; 9:e2202564. [PMID: 35905489 PMCID: PMC9507389 DOI: 10.1002/advs.202202564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 06/08/2022] [Indexed: 06/15/2023]
Abstract
Boundary obstructed topological phases caused by Wannier orbital shift between ordinary atomic sites are proposed, which, however, cannot be indicated by symmetry eigenvalues at high symmetry momenta (symmetry indicators) in bulk. On the open boundary, Wannier charge centers can shift to different atoms from those in bulk, leading to in-gap surface states, higher-order hinge states or corner states. To demonstrate such orbital shift-induced boundary obstructed topological insulators, eight material candidates are predicted, all of which are overlooked in the present topological databases. Metallic surface states, hinge states, or corner states cover the large bulk energy gap (e.g., more than 1 eV in TlGaTe2 ) at related boundary, which are ready for experimental detection. Additionally, these materials are also fragile topological insulators with hourglass-like surface states.
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Affiliation(s)
- Ning Mao
- School of PhysicsState Key Laboratory of Crystal MaterialsShandong UniversityJinan250100China
| | - Runhan Li
- School of PhysicsState Key Laboratory of Crystal MaterialsShandong UniversityJinan250100China
| | - Ying Dai
- School of PhysicsState Key Laboratory of Crystal MaterialsShandong UniversityJinan250100China
| | - Baibiao Huang
- School of PhysicsState Key Laboratory of Crystal MaterialsShandong UniversityJinan250100China
| | - Binghai Yan
- Department of Condensed Matter PhysicsWeizmann Institute of ScienceRehovotIsrael
| | - Chengwang Niu
- School of PhysicsState Key Laboratory of Crystal MaterialsShandong UniversityJinan250100China
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22
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Franklin GF, Balocchi A, Taberna PL, Barnabe A, Barbosa JB, Blei M, Tongay S, Marie X, Urita K, Chane-Ching JY. Mitigation of Edge and Surface States Effects in Two-Dimensional WS 2 for Photocatalytic H 2 Generation. ChemSusChem 2022; 15:e202200169. [PMID: 35230739 DOI: 10.1002/cssc.202200169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 03/01/2022] [Indexed: 06/14/2023]
Abstract
Large scale development of the 2D transition metal di-chalcogenides (TMDC) relies on landmark improvement in performance, which could emerge from nanostructuration. Using p-WS2 nanoflakes with different degrees of exfoliation and fracturing, perspectives were provided to develop high-surface-area 2D p-WS2 films for the photocatalytic hydrogen generation. The critical role of inter-nanoflakes contacts within high-surface-area 2D films was demonstrated, highlighting the benefit of plane/plane versus edge/plane contacts. Evidence of the high density of surface states displayed by these 2D films was provided through electrochemical measurements. In addition to operating as recombination centers, the surface states were shown to give rise to deleterious Fermi-level pinning (FLP), which dramatically decreased the efficiency of charge carrier separation. Lastly, promising strategies yielding FLP suppression via surface states modification were proposed. In particular, use of a multifunctional ultrathin film displaying healing, catalytic, and n-type semiconduction properties was shown to greatly enhance charge carrier separation and transport to the photo-electrode/electrolyte interface. When the 2D photoelectrodes were fabricated with the above prerequisites (i. e., a high proportion of plane/plane contacts and a successful surface states chemical modification), a photocurrent up to 4.5 mA cm-2 was achieved for the first time on 2D p-WS2 photocathodes for hydrogen generation.
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Affiliation(s)
| | - Andrea Balocchi
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Av. Rangueil, 31077, Toulouse, France
| | - Pierre-Louis Taberna
- UPS, CNRS, CIRIMAT, Université de Toulouse, 118 Route de Narbonne, F-31062, Toulouse, France
| | - Antoine Barnabe
- UPS, CNRS, CIRIMAT, Université de Toulouse, 118 Route de Narbonne, F-31062, Toulouse, France
| | - Juliana Barros Barbosa
- UPS, CNRS, CIRIMAT, Université de Toulouse, 118 Route de Narbonne, F-31062, Toulouse, France
| | - Mark Blei
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona, 85287, USA
| | - Sefaattin Tongay
- School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona, 85287, USA
| | - Xavier Marie
- Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Av. Rangueil, 31077, Toulouse, France
| | - Koki Urita
- Department of Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki, 852-8521, Japan
| | - Jean Yves Chane-Ching
- UPS, CNRS, CIRIMAT, Université de Toulouse, 118 Route de Narbonne, F-31062, Toulouse, France
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23
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Mori R, Wang K, Morimoto T, Ciocys S, Denlinger JD, Paglione J, Lanzara A. Observation of a Flat and Extended Surface State in a Topological Semimetal. Materials (Basel) 2022; 15:ma15082744. [PMID: 35454435 PMCID: PMC9026440 DOI: 10.3390/ma15082744] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Revised: 04/05/2022] [Accepted: 04/06/2022] [Indexed: 11/16/2022]
Abstract
A flat band structure in momentum space is considered key for the realization of novel phenomena. A topological flat band, also known as a drumhead state, is an ideal platform to drive new exotic topological quantum phases. Using angle-resolved photoemission spectroscopy experiments, we reveal the emergence of a highly localized surface state in a topological semimetal BaAl4 and provide its full energy and momentum space topology. We find that the observed surface state is localized in momentum, inside a square-shaped bulk Dirac nodal loop, and in energy, leading to a flat band and a peak in the density of state. These results imply this class of materials as an experimental realization of drumhead surface states and provide an important reference for future studies of the fundamental physics of correlated quantum effects in topological materials.
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Affiliation(s)
- Ryo Mori
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; (R.M.); (S.C.)
- Applied Science & Technology, University of California, Berkeley, CA 94720, USA
| | - Kefeng Wang
- Maryland Quantum Materials Center, Department of Physics, University of Maryland, College Park, MD 20742, USA; (K.W.); (J.P.)
| | - Takahiro Morimoto
- Department of Applied Physics, The University of Tokyo, Hongo, Tokyo 113-8656, Japan;
- JST, PRESTO, Kawaguchi 332-0012, Japan
| | - Samuel Ciocys
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; (R.M.); (S.C.)
- Department of Physics, University of California, Berkeley, CA 94720, USA
| | - Jonathan D. Denlinger
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA;
| | - Johnpierre Paglione
- Maryland Quantum Materials Center, Department of Physics, University of Maryland, College Park, MD 20742, USA; (K.W.); (J.P.)
| | - Alessandra Lanzara
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; (R.M.); (S.C.)
- Department of Physics, University of California, Berkeley, CA 94720, USA
- Correspondence:
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24
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Usman E, Barzgar Vishlaghi M, Kahraman A, Solati N, Kaya S. Modifying the Electron-Trapping Process at the BiVO 4 Surface States via the TiO 2 Overlayer for Enhanced Water Oxidation. ACS Appl Mater Interfaces 2021; 13:60602-60611. [PMID: 34881879 DOI: 10.1021/acsami.1c16847] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
BiVO4 is one of the most promising photoanode candidates to achieve high-efficiency water splitting. However, overwhelming charge recombination at the interface limits its water oxidation activity. In this study, we show that the water oxidation activity of the BiVO4 photoanode is significantly boosted by the TiO2 overlayer prepared by atomic layer deposition. With a TiO2 overlayer of an optimized thickness, the photocurrent at 1.23 VRHE increased from 0.64 to 1.1 mA·cm-2 under front illumination corresponding to 72% enhancement. We attribute this substantial improvement to enhanced charge separation and suppression of surface recombination due to surface-state passivation. We provide direct evidence via transient photocurrent measurements that the TiO2 overlayer significantly decreases the photogenerated electron-trapping process at the BiVO4 surface. Electron-trapping passivation leads to enhanced electron photoconductivity, which results in higher photocurrent enhancement under front illumination rather than back illumination. This feature can be particularly useful for wireless tandem devices for water splitting as the higher band gap photoanodes are typically utilized with front illumination in such configurations. Even though the electron-trapping process is eliminated completely at higher TiO2 overlayer thicknesses, the charge-transfer resistance at the surface also increases significantly, resulting in a diminished photocurrent. We demonstrate that the ultrathin TiO2 overlayer can be used to fine tune the surface properties of BiVO4 and may be used for similar purposes for other photoelectrode systems and other photoelectrocatalytic reactions.
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Affiliation(s)
- Emre Usman
- Materials Science and Engineering, Koç University, 34450 Istanbul, Turkey
- Koç University Tüpraş Energy Center (KUTEM), 34450 Istanbul, Turkey
| | - Mahsa Barzgar Vishlaghi
- Materials Science and Engineering, Koç University, 34450 Istanbul, Turkey
- Koç University Tüpraş Energy Center (KUTEM), 34450 Istanbul, Turkey
| | - Abdullah Kahraman
- Materials Science and Engineering, Koç University, 34450 Istanbul, Turkey
- Koç University Tüpraş Energy Center (KUTEM), 34450 Istanbul, Turkey
| | - Navid Solati
- Materials Science and Engineering, Koç University, 34450 Istanbul, Turkey
- Koç University Tüpraş Energy Center (KUTEM), 34450 Istanbul, Turkey
| | - Sarp Kaya
- Materials Science and Engineering, Koç University, 34450 Istanbul, Turkey
- Koç University Tüpraş Energy Center (KUTEM), 34450 Istanbul, Turkey
- Department of Chemistry, Koç University, 34450 Istanbul, Turkey
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25
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Mahler DM, Müller VL, Thienel C, Wiedenmann J, Beugeling W, Buhmann H, Molenkamp LW. Massive and Topological Surface States in Tensile-Strained HgTe. Nano Lett 2021; 21:9869-9874. [PMID: 34812638 DOI: 10.1021/acs.nanolett.1c02456] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Magneto-transport measurements on gated high-mobility heterostructures containing a 60 nm layer of tensile-strained HgTe, a three-dimensional topological insulator, show well-developed Hall quantization from surface states both in the n- as well as in the p-type regime. While the n-type behavior is due to transport in the topological surface state of the material, we find from 8-orbital k·p calculations that the p-type transport results from massive Volkov-Pankratov states. Their formation prevents the Dirac point and thus the p-conducting topological surface state from being accessible in transport experiments. This interpretation is supported by low-field magneto-transport experiments demonstrating the coexistence of n-conducting topological surface states and p-conducting Volkov-Pankratov states at the relevant gate voltages.
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Affiliation(s)
- David M Mahler
- Institute for Topological Insulators and Physikalisches Institut, Experimentelle Physik III, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Valentin L Müller
- Institute for Topological Insulators and Physikalisches Institut, Experimentelle Physik III, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Cornelius Thienel
- Institute for Topological Insulators and Physikalisches Institut, Experimentelle Physik III, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Jonas Wiedenmann
- Institute for Topological Insulators and Physikalisches Institut, Experimentelle Physik III, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Wouter Beugeling
- Institute for Topological Insulators and Physikalisches Institut, Experimentelle Physik III, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Hartmut Buhmann
- Institute for Topological Insulators and Physikalisches Institut, Experimentelle Physik III, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Laurens W Molenkamp
- Institute for Topological Insulators and Physikalisches Institut, Experimentelle Physik III, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
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26
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Lin P, Fang F, Zhang L, Li Y, Wang K. Various Nodal Lines in P6 3/mmc-type TiTe Topological Metal and its (001) Surface State. Front Chem 2021; 9:755350. [PMID: 34650960 PMCID: PMC8510513 DOI: 10.3389/fchem.2021.755350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Accepted: 09/10/2021] [Indexed: 11/13/2022] Open
Abstract
Searching for existing topological materials is a hot topic in quantum and computational chemistry. This study uncovers P63/mmc type TiTe compound—an existing material—is a newly discovered topological metal that hosts the various type of nodal line states. Different nodal line states normally exhibit different properties; they may have their individual applications. We report that TiTe hosts I, II, and hybrid type nodal line (NL) states at its ground state without chemical doping and strain engineering effects. Specifically, two type I NLs, two hybrid-type NLs, and one Γ—centered type II NL can be found in the kz = 0 plane. Moreover, the spin-orbit coupling induced gaps for these NLs are very small and within acceptable limits. The surface states of the TiTe (001) plane were determined to provide strong evidence for the appearance of the three types of NLs in TiTe. We also provide a reference for the data of the dynamic and mechanical properties of TiTe. We expect that the proposed NL states in TiTe can be obtained in future experiments.
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Affiliation(s)
- Peng Lin
- Engineering and Technology Center, The Fourth Medical College of Harbin Medical University, Harbin, China
| | - Fang Fang
- Engineering and Technology Center, The Fourth Medical College of Harbin Medical University, Harbin, China
| | - Li Zhang
- Changchun Institute of Technology, Changchun, China
| | - Yang Li
- Engineering and Technology Center, The Fourth Medical College of Harbin Medical University, Harbin, China.,Nanoscience and Engineering and Technology Electrophysiology Research Center, The Fourth Medical College of Harbin Medical University, Harbin, China
| | - Kai Wang
- Engineering and Technology Center, The Fourth Medical College of Harbin Medical University, Harbin, China.,Nanoscience and Engineering and Technology Electrophysiology Research Center, The Fourth Medical College of Harbin Medical University, Harbin, China
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27
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Wang Y, Nasreen S, Kamal D, Li Z, Wu C, Huo J, Chen L, Ramprasad R, Cao Y. Tuning Surface States of Metal/Polymer Contacts Toward Highly Insulating Polymer-Based Dielectrics. ACS Appl Mater Interfaces 2021; 13:46142-46150. [PMID: 34520160 DOI: 10.1021/acsami.1c12854] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Metal-polymer interface plays a crucial role in controlling the dielectric performance in all flexible electronics. Ideally, the formation of the Schottky barrier due to the large band offset of the electron affinity of the polymer over the work function of the electrode should sufficiently impede the charge injection. Arguably, however, such an injection barrier has hardly been indisputably verified in polymer-metal junctions due to the ever-existing surface states, which dramatically compromise the barrier thus leading to undesired high electrical conduction. Here, we demonstrate experimentally a clear negative correlation between the breakdown strength and the density of surface states in polymer dielectrics. The existence of surface states reduces the effective barrier height for charge injection, as further revealed by density functional theory calculations and photoinjection current measurements. Based on these findings, we present a surface engineering method to enhance the breakdown strength with the application of nanocoatings on polymer films to eliminate surface states. The density of surface states is reduced by 2 orders of magnitude when the polymer is coated with a layer of two-dimensional hexagonal boron nitride nanosheets, leading to about 100% enhancement of breakdown strength. This work reveals the critical role played by surface states on electrical breakdown and provides a versatile surface engineering strategy to curtail surface states, broadly applicable for all polymer dielectrics.
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Affiliation(s)
- Yifei Wang
- Electrical Insulation Research Center, Institute of Materials Science, University of Connecticut, 97 N Eagleville Road, Storrs, Connecticut 06269, United States
| | - Shamima Nasreen
- Electrical Insulation Research Center, Institute of Materials Science, University of Connecticut, 97 N Eagleville Road, Storrs, Connecticut 06269, United States
| | - Deepak Kamal
- School of Materials Science and Engineering, Georgia Institute of Technology, 771 Ferst Drive NW, Atlanta, Georgia 30332, United States
| | - Zongze Li
- Electrical Insulation Research Center, Institute of Materials Science, University of Connecticut, 97 N Eagleville Road, Storrs, Connecticut 06269, United States
- Department of Electrical and Computer Engineering, University of Connecticut, 371 Fairfield Way, Storrs, Connecticut 06269, United States
| | - Chao Wu
- Electrical Insulation Research Center, Institute of Materials Science, University of Connecticut, 97 N Eagleville Road, Storrs, Connecticut 06269, United States
| | - Jindong Huo
- Electrical Insulation Research Center, Institute of Materials Science, University of Connecticut, 97 N Eagleville Road, Storrs, Connecticut 06269, United States
| | - Lihua Chen
- School of Materials Science and Engineering, Georgia Institute of Technology, 771 Ferst Drive NW, Atlanta, Georgia 30332, United States
| | - Rampi Ramprasad
- School of Materials Science and Engineering, Georgia Institute of Technology, 771 Ferst Drive NW, Atlanta, Georgia 30332, United States
| | - Yang Cao
- Electrical Insulation Research Center, Institute of Materials Science, University of Connecticut, 97 N Eagleville Road, Storrs, Connecticut 06269, United States
- Department of Electrical and Computer Engineering, University of Connecticut, 371 Fairfield Way, Storrs, Connecticut 06269, United States
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28
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Fujii J, Ghosh B, Vobornik I, Bari Sarkar A, Mondal D, Kuo CN, Bocquet F, Zhang L, Boukhvalov DW, Lue CS, Agarwal A, Politano A. Mitrofanovite Pt 3Te 4: A Topological Metal with Termination-Dependent Surface Band Structure and Strong Spin Polarization. ACS Nano 2021; 15:14786-14793. [PMID: 34472336 PMCID: PMC8482756 DOI: 10.1021/acsnano.1c04766] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Accepted: 08/10/2021] [Indexed: 06/13/2023]
Abstract
Due to their peculiar quasiparticle excitations, topological metals have high potential for applications in the fields of spintronics, catalysis, and superconductivity. Here, by combining spin- and angle-resolved photoemission spectroscopy, scanning tunneling microscopy/spectroscopy, and density functional theory, we discover surface-termination-dependent topological electronic states in the recently discovered mitrofanovite Pt3Te4. Mitrofanovite crystal is formed by alternating, van der Waals bound layers of Pt2Te2 and PtTe2. Our results demonstrate that mitrofanovite is a topological metal with termination-dependent (i) electronic band structure and (ii) spin texture. Despite their distinct electronic character, both surface terminations are characterized by electronic states exhibiting strong spin polarization with a node at the Γ point and sign reversal across the Γ point, indicating their topological nature and the possibility of realizing two distinct electronic configurations (both of them with topological features) on the surface of the same material.
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Affiliation(s)
- Jun Fujii
- CNR-IOM,
TASC Laboratory, Area Science Park-Basovizza, 34139 Trieste, Italy
| | - Barun Ghosh
- Department
of Physics, Indian Institute of Technology
Kanpur, Kanpur 208016, India
| | - Ivana Vobornik
- CNR-IOM,
TASC Laboratory, Area Science Park-Basovizza, 34139 Trieste, Italy
| | - Anan Bari Sarkar
- Department
of Physics, Indian Institute of Technology
Kanpur, Kanpur 208016, India
| | - Debashis Mondal
- CNR-IOM,
TASC Laboratory, Area Science Park-Basovizza, 34139 Trieste, Italy
| | - Chia-Nung Kuo
- Department
of Physics, National Cheng Kung University, 1 Ta-Hsueh Road, 70101 Tainan, Taiwan
- Taiwan
Consortium of Emergent Crystalline Materials, Ministry of Science and Technology, Taipei 10601, Taiwan
| | - François
C. Bocquet
- Peter
Grünberg Institut (PGI-3), Forschungszentrum
Jülich, 52425 Jülich, Germany
- Jülich
Aachen Research Alliance (JARA), Fundamentals
of Future Information Technology, 52425 Jülich, Germany
| | - Lixue Zhang
- College
of
Chemistry and Chemical Engineering, Qingdao
University, Qingdao 266071, Shandong, P.
R. China
| | - Danil W. Boukhvalov
- College of
Science, Institute of Materials Physics and Chemistry, Nanjing Forestry University, Nanjing 210037, P. R. China
- Institute
of Physics and Technology, Ural Federal
University, Mira Street
19, 620002 Ekaterinburg, Russia
| | - Chin Shan Lue
- Department
of Physics, National Cheng Kung University, 1 Ta-Hsueh Road, 70101 Tainan, Taiwan
- Taiwan
Consortium of Emergent Crystalline Materials, Ministry of Science and Technology, Taipei 10601, Taiwan
| | - Amit Agarwal
- Department
of Physics, Indian Institute of Technology
Kanpur, Kanpur 208016, India
| | - Antonio Politano
- INSTM and
Department of Physical and Chemical Sciences, University of L’Aquila, via Vetoio, 67100 L’Aquila
(AQ), Italy
- CNR-IMM
Istituto per la Microelettronica e Microsistemi, VIII strada 5, I-95121 Catania, Italy
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29
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Li J, Chen H, Triana CA, Patzke GR. Hematite Photoanodes for Water Oxidation: Electronic Transitions, Carrier Dynamics, and Surface Energetics. Angew Chem Int Ed Engl 2021; 60:18380-18396. [PMID: 33761172 DOI: 10.1002/anie.202101783] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Indexed: 11/08/2022]
Abstract
We review the current understanding of charge carriers in model hematite photoanodes at different stages. The origin of charge carriers is discussed based on the electronic structure and absorption features, highlighting the controversial assignment of the electronic transitions near the absorption edge. Next, the dynamic evolution of charge carriers is analyzed both on the ultrafast and on the surface reaction timescales, with special emphasis on the arguable spectroscopic assignment of electrons/holes and their kinetics. Further, the competitive charge transfer centers at the solid-liquid interface are reviewed, and the chemical nature of relevant surface states is updated. Finally, an overview on the function of widely employed surface cocatalysts is given to illustrate the complex influence of physiochemical modifications on the charge carrier dynamics. The understanding of charge carriers from their origin all the way to their interfacial transfer is vital for the future of photoanode design.
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Affiliation(s)
- Jingguo Li
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
| | - Hang Chen
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
| | - Carlos A Triana
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
| | - Greta R Patzke
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
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30
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Zhu Y, Lin S, Gao W, Zhang M, Yang C, Feng P, Xu C, Wang ZL. Effects of Oxygen Vacancies and Cation Valence States on the Triboelectric Property of Substoichiometric Oxide Films. ACS Appl Mater Interfaces 2021; 13:35795-35803. [PMID: 34297527 DOI: 10.1021/acsami.1c09248] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Temperature effects on the contact electrification (CE) is of great interest. Here, different kinds of substoichiometric oxide films, such as TiO2-x, Al2O3-x, Ta2O5-x, and Cr2O3-x, are deposited and annealed at different temperatures, and the CE between the films and a Pt-coated tip is performed by using Kelvin probe force microscopy (KPFM). An intriguing finding is that the polarity on the TiO2-x surface changes from negative to positive with the increase of the sample annealing temperature in air atmosphere. Such a result is attributed to the fact that annealing under an oxidative atmosphere repairs oxygen vacancies and helps upgrade the low valency of Ti3+ to a stable high valency of Ti4+. On the contrary, after annealing occurs in an Ar/H2 atmosphere, the polarity on the TiO2-x surface reverses from positive to negative. This is mainly due to the increase of oxygen vacancies after annealing in reducing atmosphere. Through the KPFM results of Al2O3-x, Ta2O5-x, and Cr2O3-x films, the effect of oxygen vacancies is further confirmed, that is, the decrease of oxygen vacancies eases the films at capturing positive charges. Based on this, TiO2-x-based identical material triboelectric nanogenerators (IM-TENGs) are designed and prepared for the first time to control the current direction. Moreover, a surface state model for explaining the CE mechanism between the metal and annealed dielectric is proposed. This study is conducive to the development of the IM-TENGs which regulate the current direction or voltage output accurately in the future and also provides a further understanding of the dominant mechanism of electron transfer in the CE.
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Affiliation(s)
- Yongqiao Zhu
- School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou 221116, China
| | - Shiquan Lin
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, China
| | - Wenchao Gao
- Department of Civil Engineering, Monash University, Clayton 3800, Australia
| | - Miao Zhang
- School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou 221116, China
| | - Chaogui Yang
- School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou 221116, China
| | - Peizhong Feng
- School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou 221116, China
| | - Cheng Xu
- School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou 221116, China
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, China
| | - Zhong Lin Wang
- Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, China
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0245, United States
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31
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Xie H, Zhang T, Xie R, Hou Z, Ji X, Pang Y, Chen S, Titirici MM, Weng H, Chai G. Facet Engineering to Regulate Surface States of Topological Crystalline Insulator Bismuth Rhombic Dodecahedrons for Highly Energy Efficient Electrochemical CO 2 Reduction. Adv Mater 2021; 33:e2008373. [PMID: 34174114 DOI: 10.1002/adma.202008373] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 04/13/2021] [Indexed: 05/03/2023]
Abstract
Bismuth (Bi) is a topological crystalline insulator (TCI), which has gapless topological surface states (TSSs) protected by a specific crystalline symmetry that strongly depends on the facet. Bi is also a promising electrochemical CO2 reduction reaction (ECO2 RR) electrocatalyst for formate production. In this study, single-crystalline Bi rhombic dodecahedrons (RDs) exposed with (104) and (110) facets are developed. The Bi RDs demonstrate a very low overpotential and high selectivity for formate production (Faradic efficiency >92.2%) in a wide partial current density range from 9.8 to 290.1 mA cm-2 , leading to a remarkably high full-cell energy efficiency (69.5%) for ECO2 RR. The significantly reduced overpotential is caused by the enhanced *OCHO adsorption on the Bi RDs. The high selectivity of formate can be ascribed to the TSSs and the trivial surface states opening small gaps in the bulk gap on Bi RDs, which strengthens and stabilizes the preferentially adsorbed *OCHO and mitigates the competing adsorption of *H during ECO2 RR. This study describes a promising application of Bi RDs for high-rate formate production and high-efficiency energy storage of intermittent renewable electricity. Optimizing the geometry of TCIs is also proposed as an effective strategy to tune the TSSs of topological catalysts.
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Affiliation(s)
- Huan Xie
- State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, P. R. China
- School of Chemical Science, University of Chinese Academy of Sciences, Beijing, 100049, China
- Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou, Fujian, 350108, P. R. China
| | - Tan Zhang
- Beijing National Research Center for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Ruikuan Xie
- State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, P. R. China
- School of Chemical Science, University of Chinese Academy of Sciences, Beijing, 100049, China
- Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou, Fujian, 350108, P. R. China
| | - Zhufeng Hou
- State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, P. R. China
- School of Chemical Science, University of Chinese Academy of Sciences, Beijing, 100049, China
- Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou, Fujian, 350108, P. R. China
| | - Xuecong Ji
- Beijing National Research Center for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Yongyu Pang
- State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, P. R. China
- School of Chemical Science, University of Chinese Academy of Sciences, Beijing, 100049, China
- Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou, Fujian, 350108, P. R. China
| | - Shaoqing Chen
- Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen, Guangdong, 518055, P. R. China
| | | | - Hongming Weng
- Beijing National Research Center for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong, 523808, China
| | - Guoliang Chai
- State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, P. R. China
- School of Chemical Science, University of Chinese Academy of Sciences, Beijing, 100049, China
- Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou, Fujian, 350108, P. R. China
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32
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Li R, Lv B, Tao H, Shi J, Chong Y, Zhang B, Chen H. Ideal type-II Weyl points in topological circuits. Natl Sci Rev 2021; 8:nwaa192. [PMID: 34691684 PMCID: PMC8310763 DOI: 10.1093/nsr/nwaa192] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Revised: 05/19/2020] [Accepted: 08/19/2020] [Indexed: 11/21/2022] Open
Abstract
Weyl points (WPs), nodal degenerate points in three-dimensional (3D) momentum space, are said to be 'ideal' if they are symmetry-related and well-separated, and reside at the same energy and far from nontopological bands. Although type-II WPs have unique spectral characteristics compared with type-I counterparts, ideal type-II WPs have not yet been reported because of a lack of an experimental platform with enough flexibility to produce strongly tilted dispersion bands. Here, we experimentally realize a topological circuit that hosts only topological bands with a minimal number of four ideal type-II WPs. By stacking two-dimensional (2D) layers of inductor-capacitor (LC) resonator dimers with the broken parity inversion symmetry (P), we achieve a strongly tilted band structure with two group velocities in the same direction, and topological surface states in an incomplete bandgap. Our results establish an ideal system for the further study of Weyl physics and other exotic topological phenomena.
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Affiliation(s)
- Rujiang Li
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027, China
- ZJU-Hangzhou Global Science and Technology Innovation Center, Key Laboratory of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, Zhejiang University, Hangzhou 310027, China
| | - Bo Lv
- Key Laboratory of In-Fiber Integrated Optics of Ministry of Education, College of Physics and Optoelectronic Engineering, Harbin Engineering University, Harbin 150001, China
| | - Huibin Tao
- School of Software Engineering, Xi’an Jiaotong University, Xi’an 710054, China
| | - Jinhui Shi
- Key Laboratory of In-Fiber Integrated Optics of Ministry of Education, College of Physics and Optoelectronic Engineering, Harbin Engineering University, Harbin 150001, China
| | - Yidong Chong
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- Centre for Disruptive Photonic Technologies, Nanyang Technological University, Singapore 637371, Singapore
| | - Baile Zhang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- Centre for Disruptive Photonic Technologies, Nanyang Technological University, Singapore 637371, Singapore
| | - Hongsheng Chen
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027, China
- ZJU-Hangzhou Global Science and Technology Innovation Center, Key Laboratory of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, Zhejiang University, Hangzhou 310027, China
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33
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Shrestha K, Miertschin D, Sankar R, Lorenz B, Chu CW. Large magnetoresistance and quantum oscillations in Sn 0.05Pb 0.95Te. J Phys Condens Matter 2021; 33:335501. [PMID: 34062517 DOI: 10.1088/1361-648x/ac06ed] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Accepted: 06/01/2021] [Indexed: 06/12/2023]
Abstract
We have synthesized high-quality single crystals of SnxPb1-xTe and carried out detailed studies of the magnetotransport properties of one of the samples, Sn0.05Pb0.95Te. Longitudinal magnetoresistance increases almost linearly with increasing applied field (H) and reaches ∼310% atH= 13 T. At higher fields, both longitudinal and Hall resistance show clear Shubnikov de Haas oscillations. The oscillations are smooth and periodic, and there exists only one frequency,fα∼ 57 T. However, an additional frequency,fβ∼ 69 T, appears as the angle between the field direction and the normal to the sample surface (θ) is increased. Bothfαandfβexhibitθ-dependence;fαdecreases whereasfβincreases gradually with increasingθ. The presence of two frequencies in Sn0.05Pb0.95Te indicates that there exist two Fermi surface pockets (αandβpockets). We have constructed the Landau-level fan plot and determined the Berry phase (δ) for theαpocket to beδ∼ 0.1. Thisδvalue is very close to the expected value of 0 for a topologically trivial system.
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Affiliation(s)
- K Shrestha
- Department of Chemistry and Physics, West Texas A&M University, 2501 4th Ave, Canyon, TX 79016, United States of America
| | - D Miertschin
- Department of Chemistry and Physics, West Texas A&M University, 2501 4th Ave, Canyon, TX 79016, United States of America
| | - R Sankar
- Institute of Physics, Academia Sinica, Nankang, Taipei, 11529, Taiwan, Republic of China
| | - B Lorenz
- Texas Center for Superconductivity and Department of Physics, University of Houston, 3369 Cullen Boulevard, Houston, TX 77204-5002, United States of America
| | - C W Chu
- Texas Center for Superconductivity and Department of Physics, University of Houston, 3369 Cullen Boulevard, Houston, TX 77204-5002, United States of America
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, United States of America
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34
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Li Y, Xia J, Khenata R, Kuang M. First-principle investigation of all types of topological nodal lines in a realistic P6 3/mmc type titanium selenide. J Phys Condens Matter 2021; 33:285505. [PMID: 33412521 DOI: 10.1088/1361-648x/abd999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 01/07/2021] [Indexed: 06/12/2023]
Abstract
Topological nodal line (TNL) materials with one-dimensional band-crossing points (BCPs) exhibit interesting electronic characteristics and have special applications in electronic devices. Normally, based on the slopes of the crossing bands, the BCPs can be divided into two types, i.e., type I and type II nodal points. Based on the combination of the different types of nodal points, the nodal lines (NLs) can be divided into three categories: (i) type I NL, type II NL, and hybrid NL, these being formed by type I nodal points, type II nodal points, and type I and II nodal points, respectively. Compared with the large number of predicted type I NL materials, there are less type II and hybrid NL materials. In this study, it is predicted that P63/mmc type TiSe metal is a topological material which exhibits all types of NL states. Furthermore, the dynamic stability as well as the effect of spin-orbit coupling on the topological signatures are examined. Also, the nontrivial surface states are shown to provide evidence for the occurrence of the NL states. This novel material can be seen as a good platform to use for further investigations on the three types of NLs and diverse fermions.
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Affiliation(s)
- Yang Li
- Department of Physics, Chongqing University of Arts and Sciences, Chongqing 402160, People's Republic of China
| | - Jihong Xia
- Department of Physics, Chongqing University of Arts and Sciences, Chongqing 402160, People's Republic of China
| | - Rabah Khenata
- Laboratoire de Physique Quantique de la Matiere et de Modelisation Mathematique (LPQ3M), Universite de Mascara, Mascara 29000, Algeria
| | - Minquan Kuang
- School of Physical Science and Technology, Southwest University, Chongqing 400715, People's Republic of China
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35
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Mamiyev Z, Tegenkamp C, Pfnür H. Plasmon localization by adatoms in gold atomic wires on Si(775). J Phys Condens Matter 2021; 33:205001. [PMID: 33784647 DOI: 10.1088/1361-648x/abf37e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 03/30/2021] [Indexed: 06/12/2023]
Abstract
Self-organized gold chains on vicinal Si(111) surfaces represent prototype examples of quasi-one-dimensional objects that are stabilized by hybridization with Si surface states. Their plasmons contain important information about the unoccupied bandstructure close to the Fermi level. Using Si(775)-Au as an example, we report here the modifications of the plasmon dispersion by the simple atomic adatom species H and O. Using a combination of low energy electron diffraction and high-resolution electron energy loss spectroscopy, we study the interconnection between plasmonic excitation and the corresponding local surface structure. Both adsorbates do not destroy metallicity, but, similar to Si(553)-Au, atomic hydrogen enhances dimerization of the Au chains, which at small concentrations counteracts the disorder introduced by random adsorption. This effect, most likely caused by electron donation of H to the surface states, is missing in case of adsorbed oxygen, so that only the effect of disorder is observed. For both adsorbates increasing disorder as a function of adsorbate concentration finally results in plasmon localization and opening of a band gap.
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Affiliation(s)
- Z Mamiyev
- Institut für Festkörperphysik, Leibniz Universität Hannover, Appelstraße 2, 30167 Hannover, Germany
- Laboratorium für Nano- und Quantenengineering (LNQE), Leibniz Universität Hannover, Schneiderberg 39, 30167 Hannover, Germany
- Institut für Physik, Technische Universität Chemnitz, Reichenhainer Str. 70, D-09126 Chemnitz, Germany
| | - C Tegenkamp
- Institut für Festkörperphysik, Leibniz Universität Hannover, Appelstraße 2, 30167 Hannover, Germany
- Laboratorium für Nano- und Quantenengineering (LNQE), Leibniz Universität Hannover, Schneiderberg 39, 30167 Hannover, Germany
- Institut für Physik, Technische Universität Chemnitz, Reichenhainer Str. 70, D-09126 Chemnitz, Germany
| | - H Pfnür
- Institut für Festkörperphysik, Leibniz Universität Hannover, Appelstraße 2, 30167 Hannover, Germany
- Laboratorium für Nano- und Quantenengineering (LNQE), Leibniz Universität Hannover, Schneiderberg 39, 30167 Hannover, Germany
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36
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Rauwel P, Galeckas A, Rauwel E. Enhancing the UV Emission in ZnO-CNT Hybrid Nanostructures via the Surface Plasmon Resonance of Ag Nanoparticles. Nanomaterials (Basel) 2021; 11:452. [PMID: 33579049 PMCID: PMC7916755 DOI: 10.3390/nano11020452] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 02/04/2021] [Accepted: 02/06/2021] [Indexed: 12/16/2022]
Abstract
The crystal quality and surface states are two major factors that determine optical properties of ZnO nanoparticles (NPs) synthesized through nonaqueous sol-gel routes, and both are strongly dependent on the growth conditions. In this work, we investigate the influence of the different growth temperatures (240 and 300 °C) on the morphology, structural and crystal properties of ZnO NP. The effects of conjoining ZnO NP with carbon nanotubes (CNT) and the role of surface states in such a hybrid nanostructure are studied by optical emission and absorption spectroscopy. We demonstrate that depending on the synthesis conditions, activation or passivation of certain surface states may occur. Next, silver nanoparticles are incorporated into ZnO-CNT nanostructures to explore the plasmon-exciton coupling effect. The observed enhanced excitonic and suppressed defect-related emissions along with blue-shifted optical band gap suggest an intricate interaction of Burstein-Moss, surface plasmon resonance and surface band-bending effects behind the optical phenomena in hybrid ZnO-CNT-Ag nanocomposites.
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Affiliation(s)
- Protima Rauwel
- Institute of Technology, Estonian University of Life Sciences, 51014 Tartu, Estonia;
| | - Augustinas Galeckas
- Department of Physics, University of Oslo, P.O. Box 1048 Blindern, 0316 Oslo, Norway;
| | - Erwan Rauwel
- Institute of Technology, Estonian University of Life Sciences, 51014 Tartu, Estonia;
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37
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Sun X, Tiwari D, Fermin DJ. Promoting Active Electronic States in LaFeO 3 Thin-Films Photocathodes via Alkaline-Earth Metal Substitution. ACS Appl Mater Interfaces 2020; 12:31486-31495. [PMID: 32539332 DOI: 10.1021/acsami.0c08174] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The effects of alkaline-earth metal cation (AMC; Mg2+, Ca2+, Sr2+, and Ba2+) substitution on the photoelectrochemical properties of phase-pure LaFeO3 (LFO) thin-films are elucidated by X-ray photoemission spectroscopy (XPS), X-ray diffraction (XRD), diffuse reflectance, and electrochemical impedance spectroscopy (EIS). XRD confirms the formation of single-phase cubic LFO thin films with a rather complex dependence on the nature of the AMC and extent of substitution. Interestingly, subtle trends in lattice constant variations observed in XRD are closely correlated with shifts in the binding energies of Fe 2p3/2 and O 1s orbitals associated with the perovskite lattice. We establish a scaling factor between these two photoemission peaks, unveiling key correlation between Fe oxidation state and Fe-O covalency. Diffuse reflectance shows that optical transitions are little affected by AMC substitution below 10%, which are dominated by a direct bandgap transition close to 2.72 eV. Differential capacitance data obtained from EIS confirm the p-type characteristic of pristine LFO thin-films, revealing the presence of sub-bandgap electronic state (A-states) close to the valence band edge. The density of A-states is decreased upon AMC substitution, while the overall capacitance increases (increase in dopant level) and the apparent flat-band potential shifts toward more positive potentials. This behavior is consistent with the change in the valence band photoemission edge. In addition, capacitance data of cation-substituted films show the emergence of deeper states centered around 0.6 eV above the valence band edge (B-states). Photoelectrochemical responses toward the hydrogen evolution and oxygen reduction reactions in alkaline solutions show a complex dependence on alkaline-earth metal incorporation, reaching incident-photon-to-current conversion efficiency close to 20% in oxygen saturated solutions. We rationalize the photoresponses of the LFO films in terms of the effect sub-bandgap states on majority carrier mobility, charge transfer, and recombination kinetics.
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Affiliation(s)
- Xin Sun
- School of Chemistry, University of Bristol, Cantocks Close, Bristol BS8 1TS, U.K
| | - Devendra Tiwari
- School of Chemistry, University of Bristol, Cantocks Close, Bristol BS8 1TS, U.K
| | - David J Fermin
- School of Chemistry, University of Bristol, Cantocks Close, Bristol BS8 1TS, U.K
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38
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Jiang X, Sima W, Chen G, Peng Q, Sun P. Physicochemical Characteristics and Dynamic Charge Mapping in Thermally Aged Two-Layered Polymer Considering Surface States: Experiment and Simulation. Polymers (Basel) 2020; 12:polym12030634. [PMID: 32164362 PMCID: PMC7182934 DOI: 10.3390/polym12030634] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Revised: 02/15/2020] [Accepted: 02/16/2020] [Indexed: 11/16/2022] Open
Abstract
Under operational conditions of high electric fields and elevated temperatures, the accumulation of space charges at multilayer insulation interfaces is often considered as an important factor affecting insulation performance. This study experimentally explored the influence of different thermal aging degrees (110 °C for 0, 720, 1600, 2100, and 2900 h) on physicochemical characteristics. The space charge dynamics in two-layered thermally aged PET-PET films were measured using the pulsed electro-acoustic (PEA) method and simulated on the basis of a one-dimensional modified bipolar charge transport model. The parameterization for key parameters involved in the model was analyzed through parameter sensitivity. Results indicated that the molecular structure, crystallinity, and dielectric spectra of the PET films are affected by thermal aging. The thermalization process also has noticeable effect on the surface state characteristics, which are characterized by deeper trap depth and larger trap density. Several experimental phenomena measured by the PEA method were observed on the basis of numerical simulation.
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Affiliation(s)
- Xiongwei Jiang
- State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, Chongqing 400044, China; (W.S.); (P.S.)
- Correspondence:
| | - Wenxia Sima
- State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, Chongqing 400044, China; (W.S.); (P.S.)
| | - George Chen
- School of Electronics and Computer Science, University of Southampton, Southampton SO16 1BJ, UK;
| | - Qingjun Peng
- Electric Power Research Institute of Yunnan Power Grid Corporation, Kunming 650106, China;
| | - Potao Sun
- State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, Chongqing 400044, China; (W.S.); (P.S.)
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39
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Chi S, Liang F, Chen H, Tian W, Zhang H, Yu H, Wang G, Lin Z, Hu J, Zhang H. Surface Nonlinear Optics on Centrosymmetric Dirac Nodal-Line Semimetal ZrSiS. Adv Mater 2020; 32:e1904498. [PMID: 31750581 DOI: 10.1002/adma.201904498] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Revised: 10/15/2019] [Indexed: 06/10/2023]
Abstract
Gapless surface states (SSs) are features of topological semimetals and are extensively observed. Nowadays, the emerging question is whether the SSs possess exotic and applicable properties. Here, associated with the symmetrical selection rule for nonlinear optical materials, the surface nonlinear optics on a centrosymmetric Dirac nodal-line semimetal ZrSiS crystal is studied and it is found that the SSs bring record nonlinear susceptibilities. The unprecedented conversion efficiencies for second and third harmonic generations are 0.11‰ and 0.43‰, respectively, more than ten orders of magnitude larger than the typical surface second harmonic generation. This work discovers a new route toward studying the SSs for applications in nonlinear photonics.
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Affiliation(s)
- Shumeng Chi
- State Key Laboratory of Crystal Materials and Institute of Crystal Materials, Shandong University, Jinan, 250100, China
| | - Fei Liang
- Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Hongxiang Chen
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Wendong Tian
- State Key Laboratory of Crystal Materials and Institute of Crystal Materials, Shandong University, Jinan, 250100, China
| | - Han Zhang
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology and Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province College of Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Haohai Yu
- State Key Laboratory of Crystal Materials and Institute of Crystal Materials, Shandong University, Jinan, 250100, China
| | - Gang Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Zheshuai Lin
- Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Jiangping Hu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Huaijin Zhang
- State Key Laboratory of Crystal Materials and Institute of Crystal Materials, Shandong University, Jinan, 250100, China
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Lin S, Shen R, Yao T, Lu Y, Feng S, Hao Z, Zheng H, Yan Y, Li E. Surface States Enhanced Dynamic Schottky Diode Generator with Extremely High Power Density Over 1000 W m -2. Adv Sci (Weinh) 2019; 6:1901925. [PMID: 31871865 PMCID: PMC6918112 DOI: 10.1002/advs.201901925] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 09/14/2019] [Indexed: 05/24/2023]
Abstract
The overloaded energy cost has become the main concern of the now fast developing society, which make novel energy devices with high power density of critical importance to the sustainable development of human society. Herein, a dynamic Schottky diode based generator with ultrahigh power density of 1262.0 W m-2 for sliding Fe tip on rough p-type silicon is reported. Intriguingly, the increased surface states after rough treatment lead to an extremely enhanced current density up to 2.7 × 105 A m-2, as the charged surface states can effectively accelerate the carriers through large atomic electric field, while the reflecting directions are regulated by the built-in electric field of the Schottky barrier. This research provides an open avenue for utilizing the surface states in semiconductors in a subversive way, which can co-utilize the atomic electric field and built-in electric field to harvest energy from the mechanical movements, especially for achieving an ultrahigh current density power source.
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Affiliation(s)
- Shisheng Lin
- College of MicroelectronicsCollege of Information Science and Electronic EngineeringZhejiang UniversityHangzhou310027China
- State Key Laboratory of Modern Optical InstrumentationZhejiang UniversityHangzhou310027China
| | - Runjiang Shen
- College of MicroelectronicsCollege of Information Science and Electronic EngineeringZhejiang UniversityHangzhou310027China
| | - Tianyi Yao
- College of MicroelectronicsCollege of Information Science and Electronic EngineeringZhejiang UniversityHangzhou310027China
| | - Yanghua Lu
- College of MicroelectronicsCollege of Information Science and Electronic EngineeringZhejiang UniversityHangzhou310027China
| | - Sirui Feng
- College of MicroelectronicsCollege of Information Science and Electronic EngineeringZhejiang UniversityHangzhou310027China
| | - Zhenzhen Hao
- College of MicroelectronicsCollege of Information Science and Electronic EngineeringZhejiang UniversityHangzhou310027China
| | - Haonan Zheng
- College of MicroelectronicsCollege of Information Science and Electronic EngineeringZhejiang UniversityHangzhou310027China
| | - Yanfei Yan
- College of MicroelectronicsCollege of Information Science and Electronic EngineeringZhejiang UniversityHangzhou310027China
| | - Erping Li
- Key Laboratory of Micro‐Nano Electronics and Smart System of Zhejiang ProvinceCollege of Information Science and Electronic EngineeringZhejiang UniversityHangzhou310027China
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41
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Huang J, Dong N, McEvoy N, Wang L, Coileáin CÓ, Wang H, Cullen CP, Chen C, Zhang S, Zhang L, Wang J. Surface-State Assisted Carrier Recombination and Optical Nonlinearities in Bulk to 2D Nonlayered PtS. ACS Nano 2019; 13:13390-13402. [PMID: 31661247 DOI: 10.1021/acsnano.9b06782] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Cooperite, or platinum sulfide (PtS), is a rare mineral that generally exists as microscale, irregularly shaped crystallites. The presence of impurities, in both naturally occurring and synthesized samples, has hindered the study of its optical properties in the past. In this work, we prepare large-scale, uniform PtS films in bulk to two-dimensional form through the thermally assisted conversion method. An abnormal trend is observed in linear spectral studies whereby the optical bandgap narrows as the film thickness decreases. A model based on the continuous distribution of carriers in real space, which can be regarded as a quantum well normal to the plane, is used to describe the thickness-dependent carrier recombination phenomenon. In the nonlinear optical measurements, PtS exhibits ultrafast saturable absorption and self-defocusing properties in the visible region, which are dominated by the resonant electronic nonlinearities.
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Affiliation(s)
- Jiawei Huang
- Laboratory of Micro-Nano Optoelectronic Materials and Devices, Key Laboratory of Materials for High-Power Laser , Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences , Shanghai 201800 , China
- Center of Materials Science and Optoelectronics Engineering , University of Chinese Academy of Sciences , Beijing 100049 , China
- CAS Center for Excellence in Ultra-intense Laser Science , Shanghai 201800 , China
| | - Ningning Dong
- Laboratory of Micro-Nano Optoelectronic Materials and Devices, Key Laboratory of Materials for High-Power Laser , Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences , Shanghai 201800 , China
- Center of Materials Science and Optoelectronics Engineering , University of Chinese Academy of Sciences , Beijing 100049 , China
- CAS Center for Excellence in Ultra-intense Laser Science , Shanghai 201800 , China
| | - Niall McEvoy
- Advanced Materials and BioEngineering Research (AMBER) Centre and School of Chemistry , Trinity College Dublin , Dublin 2 , Ireland
| | - Lei Wang
- Laboratory of Micro-Nano Optoelectronic Materials and Devices, Key Laboratory of Materials for High-Power Laser , Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences , Shanghai 201800 , China
- Center of Materials Science and Optoelectronics Engineering , University of Chinese Academy of Sciences , Beijing 100049 , China
- CAS Center for Excellence in Ultra-intense Laser Science , Shanghai 201800 , China
| | - Cormac Ó Coileáin
- Advanced Materials and BioEngineering Research (AMBER) Centre and School of Chemistry , Trinity College Dublin , Dublin 2 , Ireland
| | - Hongqiang Wang
- Laboratory of Micro-Nano Optoelectronic Materials and Devices, Key Laboratory of Materials for High-Power Laser , Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences , Shanghai 201800 , China
- Center of Materials Science and Optoelectronics Engineering , University of Chinese Academy of Sciences , Beijing 100049 , China
- CAS Center for Excellence in Ultra-intense Laser Science , Shanghai 201800 , China
| | - Conor P Cullen
- Advanced Materials and BioEngineering Research (AMBER) Centre and School of Chemistry , Trinity College Dublin , Dublin 2 , Ireland
| | - Chenduan Chen
- Laboratory of Micro-Nano Optoelectronic Materials and Devices, Key Laboratory of Materials for High-Power Laser , Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences , Shanghai 201800 , China
- Center of Materials Science and Optoelectronics Engineering , University of Chinese Academy of Sciences , Beijing 100049 , China
- CAS Center for Excellence in Ultra-intense Laser Science , Shanghai 201800 , China
| | - Saifeng Zhang
- Laboratory of Micro-Nano Optoelectronic Materials and Devices, Key Laboratory of Materials for High-Power Laser , Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences , Shanghai 201800 , China
- Center of Materials Science and Optoelectronics Engineering , University of Chinese Academy of Sciences , Beijing 100049 , China
- CAS Center for Excellence in Ultra-intense Laser Science , Shanghai 201800 , China
| | - Long Zhang
- Laboratory of Micro-Nano Optoelectronic Materials and Devices, Key Laboratory of Materials for High-Power Laser , Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences , Shanghai 201800 , China
- Center of Materials Science and Optoelectronics Engineering , University of Chinese Academy of Sciences , Beijing 100049 , China
- CAS Center for Excellence in Ultra-intense Laser Science , Shanghai 201800 , China
| | - Jun Wang
- Laboratory of Micro-Nano Optoelectronic Materials and Devices, Key Laboratory of Materials for High-Power Laser , Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences , Shanghai 201800 , China
- Center of Materials Science and Optoelectronics Engineering , University of Chinese Academy of Sciences , Beijing 100049 , China
- CAS Center for Excellence in Ultra-intense Laser Science , Shanghai 201800 , China
- State Key Laboratory of High Field Laser Physics , Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences , Shanghai 201800 , China
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42
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Wang R, Wu H, Chen R, Chi Y. Strong Electrochemiluminescence Emission from Oxidized Multiwalled Carbon Nanotubes. Small 2019; 15:e1901550. [PMID: 31115974 DOI: 10.1002/smll.201901550] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 04/29/2019] [Indexed: 06/09/2023]
Abstract
Carbon nanotubes (CNTs) as well-known nanomaterials are extensively studied and widely applied in various fields. Nitric acid (HNO3 ) is often used to treat CNTs for purification purposes and preparing oxidized CNTs for various applications. However, too little attention is paid to investigating the effect of HNO3 treatment on the optical properties of CNTs. In this work, it is observed for the first time that HNO3 -oxidized multiwalled carbon nanotubes (ox-MWCNTs) have strong electrochemiluminescence (ECL) activity, which enables ox-MWCNTs to become new and good ECL carbon nanomaterials after carbon quantum dots (CQDs) and graphene quantum dots (GQDs). Various characterization technologies, such as transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy, are used to reveal the relationship between ECL activity and surface states. The ECL behaviors of ox-MWCNTs are investigated in detail and a possible ECL mechanism is proposed. Finally, the new ECL nanomaterials of ox-MWCNTs are envisioned to have promising applications in sensitive ECL sensing and in the study of CNT-based catalysts.
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Affiliation(s)
- Ruina Wang
- MOE Key Laboratory for Analytical Science of Food Safety and Biology, Fujian Provincial Key Laboratory of Analysis and Detection Technology for Food Safety, and College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350108, P. R. China
| | - Haishan Wu
- MOE Key Laboratory for Analytical Science of Food Safety and Biology, Fujian Provincial Key Laboratory of Analysis and Detection Technology for Food Safety, and College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350108, P. R. China
| | - Rui Chen
- MOE Key Laboratory for Analytical Science of Food Safety and Biology, Fujian Provincial Key Laboratory of Analysis and Detection Technology for Food Safety, and College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350108, P. R. China
| | - Yuwu Chi
- MOE Key Laboratory for Analytical Science of Food Safety and Biology, Fujian Provincial Key Laboratory of Analysis and Detection Technology for Food Safety, and College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350108, P. R. China
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43
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Barton AT, Walsh LA, Smyth CM, Qin X, Addou R, Cormier C, Hurley PK, Wallace RM, Hinkle CL. Impact of Etch Processes on the Chemistry and Surface States of the Topological Insulator Bi 2Se 3. ACS Appl Mater Interfaces 2019; 11:32144-32150. [PMID: 31416305 DOI: 10.1021/acsami.9b10625] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The unique properties of topological insulators such as Bi2Se3 are intriguing for their potential implementation in novel device architectures for low power and defect-tolerant logic and memory devices. Recent improvements in the synthesis of Bi2Se3 have positioned researchers to fabricate new devices to probe the limits of these materials. The fabrication of such devices, of course, requires etching of the topological insulator, in addition to other materials including gate oxides and contacts which may impact the topologically protected surface states. In this paper, we study the impact of He+ sputtering and inductively coupled plasma Cl2 and SF6 reactive etch chemistries on the physical, chemical, and electronic properties of Bi2Se3. Chemical analysis by X-ray photoelectron spectroscopy tracks changes in the surface chemistry and Fermi level, showing preferential removal of Se that results in vacancy-induced n-type doping. Chlorine-based chemistry successfully etches Bi2Se3 but with residual Se-Se bonding and interstitial Cl species remaining after the etch. The Se vacancies and residuals can be removed with postetch anneals in a Se environment, repairing Bi2Se3 nearly to the as-grown condition. Critically, in each of these cases, angle-resolved photoemission spectroscopy (ARPES) reveals that the topologically protected surface states remain even after inducing significant surface disorder and chemical changes, demonstrating that topological insulators are quite promising for defect-tolerant electronics. Changes to the ARPES intensity and momentum broadening of the surface states are discussed. Fluorine-based etching aggressively reacts with the film resulting in a relatively thick insulating film of thermodynamically favored BiF3 on the surface, prohibiting the use of SF6-based etching in Bi2Se3 processing.
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Affiliation(s)
- Adam T Barton
- Department of Materials Science and Engineering , University of Texas at Dallas , Richardson , Texas 75080 , United States
| | - Lee A Walsh
- Department of Materials Science and Engineering , University of Texas at Dallas , Richardson , Texas 75080 , United States
- Tyndall National Institute , University College Cork , Lee Maltings Complex , Cork T12R5CP , Ireland
| | - Christopher M Smyth
- Department of Materials Science and Engineering , University of Texas at Dallas , Richardson , Texas 75080 , United States
| | - Xiaoye Qin
- Department of Materials Science and Engineering , University of Texas at Dallas , Richardson , Texas 75080 , United States
| | - Rafik Addou
- Department of Materials Science and Engineering , University of Texas at Dallas , Richardson , Texas 75080 , United States
| | - Christopher Cormier
- Department of Materials Science and Engineering , University of Texas at Dallas , Richardson , Texas 75080 , United States
| | - Paul K Hurley
- Tyndall National Institute , University College Cork , Lee Maltings Complex , Cork T12R5CP , Ireland
| | - Robert M Wallace
- Department of Materials Science and Engineering , University of Texas at Dallas , Richardson , Texas 75080 , United States
| | - Christopher L Hinkle
- Department of Materials Science and Engineering , University of Texas at Dallas , Richardson , Texas 75080 , United States
- Department of Electrical Engineering , University of Notre Dame , Notre Dame , Indiana 46556 , United States
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44
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Li G, Fu C, Shi W, Jiao L, Wu J, Yang Q, Saha R, Kamminga ME, Srivastava AK, Liu E, Yazdani AN, Kumar N, Zhang J, Blake GR, Liu X, Fahlman M, Wirth S, Auffermann G, Gooth J, Parkin S, Madhavan V, Feng X, Sun Y, Felser C. Dirac Nodal Arc Semimetal PtSn 4 : An Ideal Platform for Understanding Surface Properties and Catalysis for Hydrogen Evolution. Angew Chem Int Ed Engl 2019; 58:13107-13112. [PMID: 31342613 PMCID: PMC6772105 DOI: 10.1002/anie.201906109] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Indexed: 01/17/2023]
Abstract
Conductivity, carrier mobility, and a suitable Gibbs free energy are important criteria that determine the performance of catalysts for a hydrogen evolution reaction (HER). However, it is a challenge to combine these factors into a single compound. Herein, we discover a superior electrocatalyst for a HER in the recently identified Dirac nodal arc semimetal PtSn4 . The determined turnover frequency (TOF) for each active site of PtSn4 is 1.54 H2 s-1 at 100 mV. This sets a benchmark for HER catalysis on Pt-based noble metals and earth-abundant metal catalysts. We make use of the robust surface states of PtSn4 as their electrons can be transferred to the adsorbed hydrogen atoms in the catalytic process more efficiently. In addition, PtSn4 displays excellent chemical and electrochemical stabilities after long-term exposure in air and long-time HER stability tests.
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Affiliation(s)
- Guowei Li
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - Chenguang Fu
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - Wujun Shi
- School of Physical Science and Technology, ShanghaiTech University, 201203, Shanghai, China
| | - Lin Jiao
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - Jiquan Wu
- Department of Physics, Chemistry and Biology (IFM), Linköping University, 58183, Linköping, Sweden
| | - Qun Yang
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - Rana Saha
- Max Planck Institute for Microstructure Physics, 06120, Halle, Germany
| | - Machteld E Kamminga
- Zernike Institute for Advanced Materials, University of Groningen, 9747, AG, Groningen, The Netherlands
| | | | - Enke Liu
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - Aliza N Yazdani
- Department of Chemistry, Carleton College, MN, 55057, Northfield, USA
| | - Nitesh Kumar
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - Jian Zhang
- Department of Chemistry and Food Chemistry, Technische Universität Dresden, 01062, Dresden, Germany
| | - Graeme R Blake
- Zernike Institute for Advanced Materials, University of Groningen, 9747, AG, Groningen, The Netherlands
| | - Xianjie Liu
- Department of Physics, Chemistry and Biology (IFM), Linköping University, 58183, Linköping, Sweden
| | - Mats Fahlman
- Department of Physics, Chemistry and Biology (IFM), Linköping University, 58183, Linköping, Sweden
| | - Steffen Wirth
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - Gudrun Auffermann
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - Johannes Gooth
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - Stuart Parkin
- Max Planck Institute for Microstructure Physics, 06120, Halle, Germany
| | - Vidya Madhavan
- Department of Physics and Frederick Seitz Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Xinliang Feng
- Department of Chemistry and Food Chemistry, Technische Universität Dresden, 01062, Dresden, Germany
| | - Yan Sun
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
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45
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Alekseev PA, Sharov VA, Dunaevskiy MS, Kirilenko DA, Ilkiv IV, Reznik RR, Cirlin GE, Berkovits VL. Control of Conductivity of In xGa 1-xAs Nanowires by Applied Tension and Surface States. Nano Lett 2019; 19:4463-4469. [PMID: 31203633 DOI: 10.1021/acs.nanolett.9b01264] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The electronic properties of semiconductor AIIIBV nanowires (NWs) due to their high surface/volume ratio can be effectively controlled by NW strain and surface electronic states. We study the effect of applied tension on the conductivity of wurtzite InxGa1-xAs (x ∼ 0.8) NWs. Experimentally, conductive atomic force microscopy is used to measure the I-V curves of vertically standing NWs covered by native oxide. To apply tension, the microscope probe touching the NW side is shifted laterally to produce a tensile strain in the NW. The NW strain significantly increases the forward current in the measured I-V curves. When the strain reaches 4%, the I-V curve becomes almost linear, and the forward current increases by 3 orders of magnitude. In the latter case, the tensile strain is supposed to shift the conduction band minima below the Fermi level, whose position, in turn, is fixed by surface states. Consequently, the surface conductivity channel appears. The observed effects confirm that the excess surface arsenic is responsible for the Fermi level pinning at oxidized surfaces of III-As NWs.
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Affiliation(s)
| | - Vladislav A Sharov
- Ioffe Institute , Saint Petersburg 194021 , Russia
- Saint-Petersburg Academic University , Saint Petersburg 194021 , Russia
| | | | | | - Igor V Ilkiv
- Saint-Petersburg Academic University , Saint Petersburg 194021 , Russia
| | | | - George E Cirlin
- Saint-Petersburg Academic University , Saint Petersburg 194021 , Russia
- ITMO University , Saint Petersburg 197101 , Russia
- Saint Petersburg Electrotechnical University LETI , Saint Petersburg 197376 , Russia
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46
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Zu F, Wolff CM, Ralaiarisoa M, Amsalem P, Neher D, Koch N. Unraveling the Electronic Properties of Lead Halide Perovskites with Surface Photovoltage in Photoemission Studies. ACS Appl Mater Interfaces 2019; 11:21578-21583. [PMID: 31124647 DOI: 10.1021/acsami.9b05293] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The tremendous success of metal-halide perovskites, especially in the field of photovoltaics, has triggered a substantial number of studies in understanding their optoelectronic properties. However, consensus regarding the electronic properties of these perovskites is lacking due to a huge scatter in the reported key parameters, such as work function (Φ) and valence band maximum (VBM) values. Here, we demonstrate that the surface photovoltage (SPV) is a key phenomenon occurring at the perovskite surfaces that feature a non-negligible density of surface states, which is more the rule than an exception for most materials under study. With ultraviolet photoelectron spectroscopy (UPS) and Kelvin probe, we evidence that even minute UV photon fluxes (500 times lower than that used in typical UPS experiments) are sufficient to induce SPV and shift the perovskite Φ and VBM by several 100 meV compared to dark. By combining UV and visible light, we establish flat band conditions (i.e., compensate the surface-state-induced surface band bending) at the surface of four important perovskites, and find that all are p-type in the bulk, despite a pronounced n-type surface character in the dark. The present findings highlight that SPV effects must be considered in all surface studies to fully understand perovskites' photophysical properties.
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Affiliation(s)
- Fengshuo Zu
- Institut für Physik & IRIS Adlershof , Humboldt-Universität zu Berlin , 12489 Berlin , Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , 12489 Berlin , Germany
| | - Christian M Wolff
- Institut für Physik und Astronomie , Universität Potsdam , 14776 Potsdam , Germany
| | - Maryline Ralaiarisoa
- Institut für Physik & IRIS Adlershof , Humboldt-Universität zu Berlin , 12489 Berlin , Germany
| | - Patrick Amsalem
- Institut für Physik & IRIS Adlershof , Humboldt-Universität zu Berlin , 12489 Berlin , Germany
| | - Dieter Neher
- Institut für Physik und Astronomie , Universität Potsdam , 14776 Potsdam , Germany
| | - Norbert Koch
- Institut für Physik & IRIS Adlershof , Humboldt-Universität zu Berlin , 12489 Berlin , Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , 12489 Berlin , Germany
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47
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Cai Z, Yan Y, Liu L, Lin S, Hu X. Enhanced Charge Transfer by Passivation Layer in 3DOM Ferroelectric Heterojunction for Water Oxidation in HCO 3 - /CO 2 System. Small 2019; 15:e1804930. [PMID: 30838759 DOI: 10.1002/smll.201804930] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 01/23/2019] [Indexed: 06/09/2023]
Abstract
Photoelectrochemical carbon dioxide conversion to fuels such as carbon monoxide, methanol, and ethylene exhibits great potential to solve energy issues. Unfortunately, CO2 conversion efficiency is still low due to violent charge recombination at the photoanode. Herein, a novel 3D macroporous ferroelectric heterojunction composed of BiFeO3 and LiNbO3 is developed by a template-assisted sol-gel method, aiming at facilitating charge transfer kinetics. As expected, a tremendous enhancement of photocurrent density (300 times vs bare planar BiFeO3 film) and charge transfer efficiency (up to 76%) is obtained in the HCO3 - /CO2 system without any cocatalyst. The photoelectrochemical performance is switchable by poling to form a depolarization electric field. Photoelectrochemical impedance spectroscopy reveals that the charge transfer resistance decreases due to the synergistic effect of BiFeO3 3D macroporous skeleton and LiNbO3 passivation layer by tuning surface states. These results suggest a novel strategy for enhancing photoelectrochemical water oxidation as the anodic reaction of CO2 reduction.
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Affiliation(s)
- Zihe Cai
- State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
| | - Yang Yan
- State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
| | - Lin Liu
- State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
| | - Shengxuan Lin
- State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
| | - Xiaobin Hu
- State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
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48
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Xu C, Zhang B, Wang AC, Zou H, Liu G, Ding W, Wu C, Ma M, Feng P, Lin Z, Wang ZL. Contact-Electrification between Two Identical Materials: Curvature Effect. ACS Nano 2019; 13:2034-2041. [PMID: 30707552 DOI: 10.1021/acsnano.8b08533] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
It is known that contact-electrification (or triboelectrification) usually occurs between two different materials, which could be explained by several models for different materials systems ( Adv. Mater. 2018, 30, 1706790; Adv. Mater. 2018, 30, 1803968). But contact between two pieces of the chemically same material could also result in electrostatic charges, although the charge density is rather low, which is hard to understand from a physics point of view. In this paper, by preparing a contact-separation mode triboelectric nanogenerator using two pieces of an identical material, the direction of charge transfer during contact-electrification is studied regarding its dependence on curvatures of the sample surfaces. For materials such as polytetrafluoroethylene, fluorinated ethylene propylene, Kapton, polyester, and nylon, the positive curvature surfaces are net negatively charged, while the negative curvature surfaces tend to be net positively charged. Further verification of the above-mentioned trends was obtained under vacuum (∼1 Pa) and higher temperature (≤358 K) conditions. Based on the received data acquired for gentle contacting cases, we propose a curvature-dependent charge transfer model by introducing curvature-induced energy shifts of the surface states. However, this model is subject to be revised if the mutual contact mode turns into a sliding mode or more complicated hard-pressed contact mode, in which a rigorous contact between the two pieces of the same material could result in nanoscale damage/fracture and possible species transfer. Our study provides a primitive step toward understanding the basics of contact-electrification.
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Affiliation(s)
- Cheng Xu
- Beijing Institute of Nanoenergy and Nanosystems , Chinese Academy of Sciences , Beijing 100083 , China
- School of Materials Science and Engineering , China University of Mining and Technology , Xuzhou 221116 , China
- School of Materials Science and Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332-0245 , United States
| | - Binbin Zhang
- School of Materials Science and Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332-0245 , United States
| | - Aurelia Chi Wang
- School of Materials Science and Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332-0245 , United States
| | - Haiyang Zou
- School of Materials Science and Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332-0245 , United States
| | - Guanlin Liu
- School of Materials Science and Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332-0245 , United States
| | - Wenbo Ding
- School of Materials Science and Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332-0245 , United States
| | - Changsheng Wu
- School of Materials Science and Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332-0245 , United States
| | - Ming Ma
- School of Materials Science and Engineering , China University of Mining and Technology , Xuzhou 221116 , China
| | - Peizhong Feng
- School of Materials Science and Engineering , China University of Mining and Technology , Xuzhou 221116 , China
| | - Zhiqun Lin
- School of Materials Science and Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332-0245 , United States
| | - Zhong Lin Wang
- Beijing Institute of Nanoenergy and Nanosystems , Chinese Academy of Sciences , Beijing 100083 , China
- School of Materials Science and Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332-0245 , United States
- School of Nanoscience and Technology , University of Chinese Academy of Sciences , Beijing 100049 , China
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49
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Wei JS, Ding C, Zhang P, Ding H, Niu XQ, Ma YY, Li C, Wang YG, Xiong HM. Robust Negative Electrode Materials Derived from Carbon Dots and Porous Hydrogels for High-Performance Hybrid Supercapacitors. Adv Mater 2019; 31:e1806197. [PMID: 30537033 DOI: 10.1002/adma.201806197] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 11/12/2018] [Indexed: 05/23/2023]
Abstract
Hybrid supercapacitors generally show high power and long life spans but inferior energy densities, which are mainly caused by carbon negative electrodes with low specific capacitances. To improve the energy densities, the traditional methods include optimizing pore structures and modifying pseudocapacitive groups on the carbon materials. Here, another promising way is suggested, which has no adverse effects to the carbon materials, that is, constructing electron-rich regions on the electrode surfaces for absorbing cations as much as possible. For this aim, a series of hierarchical porous carbon materials are produced by calcinating carbon dots-hydrogel composites, which have controllable surface states including electron-rich regions. The optimal sample is employed as the negative electrode to fabricate hybrid supercapacitors, which show remarkable specific energy densities (up to 62.8-90.1 Wh kg-1 ) in different systems.
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Affiliation(s)
- Ji-Shi Wei
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, P. R. China
| | - Chen Ding
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, P. R. China
| | - Peng Zhang
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, P. R. China
| | - Hui Ding
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, P. R. China
| | - Xiao-Qing Niu
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, P. R. China
| | - Yuan-Yuan Ma
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, P. R. China
| | - Chao Li
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, P. R. China
| | - Yong-Gang Wang
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, P. R. China
| | - Huan-Ming Xiong
- Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, P. R. China
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Wang X, Cheng L, Zhu D, Wu Y, Chen M, Wang Y, Zhao D, Boothroyd CB, Lam YM, Zhu JX, Battiato M, Song JCW, Yang H, Chia EEM. Ultrafast Spin-to-Charge Conversion at the Surface of Topological Insulator Thin Films. Adv Mater 2018; 30:e1802356. [PMID: 30370615 DOI: 10.1002/adma.201802356] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 09/20/2018] [Indexed: 06/08/2023]
Abstract
Strong spin-orbit coupling, resulting in the formation of spin-momentum-locked surface states, endows topological insulators with superior spin-to-charge conversion characteristics, though the dynamics that govern it have remained elusive. Here, an all-optical method is presented, which enables unprecedented tracking of the ultrafast dynamics of spin-to-charge conversion in a prototypical topological insulator Bi2 Se3 /ferromagnetic Co heterostructure, down to the sub-picosecond timescale. Compared to pure Bi2 Se3 or Co, a giant terahertz emission is observed in the heterostructure that originates from spin-to-charge conversion, in which the topological surface states play a crucial role. A 0.12 ps timescale is identified that sets a technological speed limit of spin-to-charge conversion processes in topological insulators. In addition, it is shown that the spin-to-charge conversion efficiency is temperature independent in Bi2 Se3 as expected from the nature of the surface states, paving the way for designing next-generation high-speed optospintronic devices based on topological insulators at room temperature.
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Affiliation(s)
- Xinbo Wang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Liang Cheng
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore
| | - Dapeng Zhu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117576, Singapore
| | - Yang Wu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117576, Singapore
| | - Mengji Chen
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117576, Singapore
| | - Yi Wang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117576, Singapore
| | - Daming Zhao
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore
| | - Chris B Boothroyd
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Yeng Ming Lam
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Jian-Xin Zhu
- Theoretical Division and Center for Integrated Nanotechnologies, Los Alamos National Laboratory, NM, 87545, USA
| | - Marco Battiato
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore
- Institute of Solid State Physics, Vienna University of Technology, 1040, Vienna, Austria
| | - Justin C W Song
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore
- Institute of High Performance Computing, Agency for Science, Technology, and Research, Singapore, 138632, Singapore
| | - Hyunsoo Yang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117576, Singapore
| | - Elbert E M Chia
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore
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