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Lee R, Quesada-Cabrera R, Willis J, Iqbal A, Parkin IP, Scanlon DO, Palgrave RG. Phase Quantification of Heterogeneous Surfaces Using DFT-Simulated Valence Band Photoemission Spectra. ACS Appl Mater Interfaces 2023; 15:39956-39965. [PMID: 37552034 PMCID: PMC10450682 DOI: 10.1021/acsami.3c06638] [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: 05/10/2023] [Accepted: 07/24/2023] [Indexed: 08/09/2023]
Abstract
Quantifying the crystallographic phases present at a surface is an important challenge in fields such as functional materials and surface science. X-ray photoelectron spectroscopy (XPS) is routinely employed in surface characterization to identify and quantify chemical species through core line analysis. Valence band (VB) spectra contain characteristic but complex features that provide information on the electronic density of states (DoS) and thus can be understood theoretically using density functional theory (DFT). Here, we present a method of fitting experimental photoemission spectra with DFT models for quantitative analysis of heterogeneous systems, specifically mapping the anatase to rutile ratio across the surface of mixed-phase TiO2 thin films. The results were correlated with mapped photocatalytic activity measured using a resazurin-based smart ink. This method allows large-scale functional and surface composition mapping in heterogeneous systems and demonstrates the unique insights gained from DFT-simulated spectra on the electronic structure origins of complex VB spectral features.
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Affiliation(s)
- Roxy Lee
- Department
of Chemistry, UCL (University College London), 20 Gordon Street, London WC1H 0AJ, U.K.
| | - Raul Quesada-Cabrera
- Department
of Chemistry, UCL (University College London), 20 Gordon Street, London WC1H 0AJ, U.K.
- Department
of Chemistry, Institute of Environmental Studies and Natural Resources
(i-UNAT, FEAM), Universidad de Las Palmas
de Gran Canaria (ULPGC), Campus de Tafira, Las Palmas 35017, Spain
| | - Joe Willis
- Department
of Chemistry, UCL (University College London), 20 Gordon Street, London WC1H 0AJ, U.K.
- Thomas
Young Centre, UCL (University College London), Gower Street, London WC1E 6BT, U.K.
- Diamond
Light Source Ltd., Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, U.K.
| | - Asif Iqbal
- Materials
Engineering, McGill University, 3610 University Street, Montreal, Quebec H3A 0C5, Canada
| | - Ivan P. Parkin
- Department
of Chemistry, UCL (University College London), 20 Gordon Street, London WC1H 0AJ, U.K.
| | - David O. Scanlon
- Department
of Chemistry, UCL (University College London), 20 Gordon Street, London WC1H 0AJ, U.K.
- Thomas
Young Centre, UCL (University College London), Gower Street, London WC1E 6BT, U.K.
| | - Robert G. Palgrave
- Department
of Chemistry, UCL (University College London), 20 Gordon Street, London WC1H 0AJ, U.K.
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Dutta T, Noushin T, Tabassum S, Mishra SK. Road Map of Semiconductor Metal-Oxide-Based Sensors: A Review. Sensors (Basel) 2023; 23:6849. [PMID: 37571634 PMCID: PMC10422562 DOI: 10.3390/s23156849] [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: 04/18/2023] [Revised: 06/22/2023] [Accepted: 07/19/2023] [Indexed: 08/13/2023]
Abstract
Identifying disease biomarkers and detecting hazardous, explosive, flammable, and polluting gases and chemicals with extremely sensitive and selective sensor devices remains a challenging and time-consuming research challenge. Due to their exceptional characteristics, semiconducting metal oxides (SMOxs) have received a lot of attention in terms of the development of various types of sensors in recent years. The key performance indicators of SMOx-based sensors are their sensitivity, selectivity, recovery time, and steady response over time. SMOx-based sensors are discussed in this review based on their different properties. Surface properties of the functional material, such as its (nano)structure, morphology, and crystallinity, greatly influence sensor performance. A few examples of the complicated and poorly understood processes involved in SMOx sensing systems are adsorption and chemisorption, charge transfers, and oxygen migration. The future prospects of SMOx-based gas sensors, chemical sensors, and biological sensors are also discussed.
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Affiliation(s)
- Taposhree Dutta
- Department of Chemistry, IIEST Shibpur, Howrah 711103, West Bengal, India;
| | - Tanzila Noushin
- Department of Electrical and Computer Engineering, The University of Texas at Dallas, Richardson, TX 75080, USA;
| | - Shawana Tabassum
- Department of Electrical Engineering, The University of Texas at Tyler, Tyler, TX 75799, USA;
| | - Satyendra K. Mishra
- Danish Offshore Technology Center, Technical University of Denmark, 2800 Lyngby, Denmark
- SRCOM, Centre Technologic de Telecomunicacions de Catalunya, 08860 Castelldefels, Barcelona, Spain
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Lim T, Jo K, Lee H. Oxygen Vacancy and Valence Band Structure of Ba 0.5Sr 0.5Fe 1-xCu xO 3-δ (x = 0-0.15) with Enhanced ORR Activity for IT-SOFCs. Materials (Basel) 2023; 16:3231. [PMID: 37110066 PMCID: PMC10146722 DOI: 10.3390/ma16083231] [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: 03/24/2023] [Revised: 04/12/2023] [Accepted: 04/18/2023] [Indexed: 06/19/2023]
Abstract
The oxygen reduction reaction (ORR) activity of a Cu-doped Ba0.5Sr0.5FeO3-δ (Ba0.5Sr0.5Fe1-xCuxO3-δ, BSFCux, x = 0, 0.05, 0.10, 0.15) perovskite cathode was investigated in terms of oxygen vacancy formation and valence band structure. The BSFCux (x = 0, 0.05, 0.10, 0.15) crystallized in a cubic perovskite structure (Pm3¯m). By thermogravimetric analysis and surface chemical analysis, it was confirmed that the concentration of oxygen vacancies in the lattice increased with Cu doping. The average oxidation state of B-site ions decreased from 3.583 (x = 0) to 3.210 (x = 0.15), and the valence band maximum shifted from -0.133 eV (x = 0) to -0.222 eV (x = 0.15). The electrical conductivity of BSFCux increased with temperature because of the thermally activated small polaron hopping mechanism showing a maximum value of 64.12 S cm-1 (x = 0.15) at 500 °C. The ASR value as an indicator of ORR activity decreased by 72.6% from 0.135 Ω cm2 (x = 0) to 0.037 Ω cm2 (x = 0.15) at 700 °C. The Cu doping increased oxygen vacancy concentration and electron concentration in the valence band to promote electron exchange with adsorbed oxygen, thereby improving ORR activity.
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Affiliation(s)
| | | | - Heesoo Lee
- Correspondence: ; Tel.: +82-51-510-2388; Fax: +82-51-512-0528
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Shao Y, Hu G, Liu Z, Xu X, Zhang M, Ding C, Li Y. Determination of Band Structure of Naturally Occurring Goethite with Al Substitution: A Case Study of Zhushan Iron Zone. Materials (Basel) 2022; 15:1465. [PMID: 35208010 DOI: 10.3390/ma15041465] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 02/11/2022] [Accepted: 02/12/2022] [Indexed: 12/04/2022]
Abstract
The photocatalytic property of Fe oxide minerals has long been considered to play an important role in shaping modern terrestrial environments. However, due to the complexity of natural settings, a precise determination of the band structure of natural goethite has not been achieved. In this work, the mineralogical characteristics of natural goethite samples obtained from Zhushan, China, were systematically studied through X-ray diffraction, transmission electron microscopy, X-ray energy dispersive spectroscopy, and X-ray fluorescence spectroscopy. Afterward, the band structure for both natural and synthetic goethite samples was determined by synchrotron-based X-ray absorption and emission spectra and photoelectron spectroscopy. The band gap of natural goethite (2.25 eV) was narrower than that of its synthetic counterpart (2.55 eV), and the valence band position of natural goethite was slightly lifted (−5.06 eV) compared to that of synthetic goethite (−5.38 eV). Al doping in natural goethite crystal, as revealed by the mineralogical tests, was the main reason that contributed to this difference. The theoretical calculation showed the narrowed band gap was caused by the contribution of Al-2p orbits at the top of the valence band. Therefore, free electrons can be created under light irradiation with a shorter wavelength. The experiments showed that natural goethite can photo-catalytically degrade methyl orange, and the degradation efficiency was better (47.5%) than that of the synthetic goethite group (31.5%). This study, for the first time, revealed the band structure and confirmed the photocatalytic properties of natural goethite, which should play an important role in surface substance evolution and elemental cycling.
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Rabchinskii MK, Sysoev VV, Ryzhkov SA, Eliseyev IA, Stolyarova DY, Antonov GA, Struchkov NS, Brzhezinskaya M, Kirilenko DA, Pavlov SI, Palenov ME, Mishin MV, Kvashenkina OE, Gabdullin PG, Varezhnikov AS, Solomatin MA, Brunkov PN. A Blueprint for the Synthesis and Characterization of Thiolated Graphene. Nanomaterials (Basel) 2021; 12:45. [PMID: 35009995 PMCID: PMC8746421 DOI: 10.3390/nano12010045] [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] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Revised: 12/14/2021] [Accepted: 12/22/2021] [Indexed: 06/12/2023]
Abstract
Graphene derivatization to either engineer its physical and chemical properties or overcome the problem of the facile synthesis of nanographenes is a subject of significant attention in the nanomaterials research community. In this paper, we propose a facile and scalable method for the synthesis of thiolated graphene via a two-step liquid-phase treatment of graphene oxide (GO). Employing the core-level methods, the introduction of up to 5.1 at.% of thiols is indicated with the simultaneous rise of the C/O ratio to 16.8. The crumpling of the graphene layer upon thiolation without its perforation is pointed out by microscopic and Raman studies. The conductance of thiolated graphene is revealed to be driven by the Mott hopping mechanism with the sheet resistance values of 2.15 kΩ/sq and dependable on the environment. The preliminary results on the chemiresistive effect of these films upon exposure to ethanol vapors in the mix with dry and humid air are shown. Finally, the work function value and valence band structure of thiolated graphene are analyzed. Taken together, the developed method and findings of the morphology and physics of the thiolated graphene guide the further application of this derivative in energy storage, sensing devices, and smart materials.
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Affiliation(s)
- Maxim K. Rabchinskii
- Ioffe Institute, Politekhnicheskaya St. 26, 194021 Saint Petersburg, Russia; (S.A.R.); (I.A.E.); (G.A.A.); (D.A.K.); (S.I.P.); (P.N.B.)
| | - Victor V. Sysoev
- Department of Physics, Yuri Gagarin State Technical University of Saratov, 77 Polytechnicheskaya St., 410054 Saratov, Russia; (V.V.S.); (A.S.V.); (M.A.S.)
| | - Sergei A. Ryzhkov
- Ioffe Institute, Politekhnicheskaya St. 26, 194021 Saint Petersburg, Russia; (S.A.R.); (I.A.E.); (G.A.A.); (D.A.K.); (S.I.P.); (P.N.B.)
| | - Ilya A. Eliseyev
- Ioffe Institute, Politekhnicheskaya St. 26, 194021 Saint Petersburg, Russia; (S.A.R.); (I.A.E.); (G.A.A.); (D.A.K.); (S.I.P.); (P.N.B.)
| | - Dina Yu. Stolyarova
- National Research Centre “Kurchatov Institute”, Akademika Kurchatova pl. 1, 123182 Moscow, Russia;
| | - Grigorii A. Antonov
- Ioffe Institute, Politekhnicheskaya St. 26, 194021 Saint Petersburg, Russia; (S.A.R.); (I.A.E.); (G.A.A.); (D.A.K.); (S.I.P.); (P.N.B.)
| | - Nikolai S. Struchkov
- Center for Probe Microscopy and Nanotechnology, National Research University of Electronic Technology, Bld. 1, Shokin Square, 124498 Moscow, Russia;
| | - Maria Brzhezinskaya
- Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin, Germany;
| | - Demid A. Kirilenko
- Ioffe Institute, Politekhnicheskaya St. 26, 194021 Saint Petersburg, Russia; (S.A.R.); (I.A.E.); (G.A.A.); (D.A.K.); (S.I.P.); (P.N.B.)
| | - Sergei I. Pavlov
- Ioffe Institute, Politekhnicheskaya St. 26, 194021 Saint Petersburg, Russia; (S.A.R.); (I.A.E.); (G.A.A.); (D.A.K.); (S.I.P.); (P.N.B.)
| | - Mihail E. Palenov
- Institute of Electronics and Telecommunications, Peter the Great St. Petersburg Polytechnic University (SPbPU), Polytechnicheskaya 29, 195251 Saint Petersburg, Russia; (M.E.P.); (M.V.M.); (O.E.K.); (P.G.G.)
| | - Maxim V. Mishin
- Institute of Electronics and Telecommunications, Peter the Great St. Petersburg Polytechnic University (SPbPU), Polytechnicheskaya 29, 195251 Saint Petersburg, Russia; (M.E.P.); (M.V.M.); (O.E.K.); (P.G.G.)
| | - Olga E. Kvashenkina
- Institute of Electronics and Telecommunications, Peter the Great St. Petersburg Polytechnic University (SPbPU), Polytechnicheskaya 29, 195251 Saint Petersburg, Russia; (M.E.P.); (M.V.M.); (O.E.K.); (P.G.G.)
| | - Pavel G. Gabdullin
- Institute of Electronics and Telecommunications, Peter the Great St. Petersburg Polytechnic University (SPbPU), Polytechnicheskaya 29, 195251 Saint Petersburg, Russia; (M.E.P.); (M.V.M.); (O.E.K.); (P.G.G.)
| | - Alexey S. Varezhnikov
- Department of Physics, Yuri Gagarin State Technical University of Saratov, 77 Polytechnicheskaya St., 410054 Saratov, Russia; (V.V.S.); (A.S.V.); (M.A.S.)
| | - Maksim A. Solomatin
- Department of Physics, Yuri Gagarin State Technical University of Saratov, 77 Polytechnicheskaya St., 410054 Saratov, Russia; (V.V.S.); (A.S.V.); (M.A.S.)
| | - Pavel N. Brunkov
- Ioffe Institute, Politekhnicheskaya St. 26, 194021 Saint Petersburg, Russia; (S.A.R.); (I.A.E.); (G.A.A.); (D.A.K.); (S.I.P.); (P.N.B.)
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6
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Lewandków R, Mazur P, Trembułowicz A, Sabik A, Wasielewski R, Grodzicki M. Influence of Graphite Layer on Electronic Properties of MgO/6H-SiC(0001) Interface. Materials (Basel) 2021; 14:4189. [PMID: 34361382 DOI: 10.3390/ma14154189] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/19/2021] [Accepted: 07/20/2021] [Indexed: 12/02/2022]
Abstract
This paper concerns research on magnesium oxide layers in terms of their potential use as a gate material for SiC MOSFET structures. The two basic systems of MgO/SiC(0001) and MgO/graphite/SiC(0001) were deeply investigated in situ under ultrahigh vacuum (UHV). In both cases, the MgO layers were obtained by a reactive evaporation method. Graphite layers terminating the SiC(0001) surface were formed by thermal annealing in UHV. The physicochemical properties of the deposited MgO layers and the systems formed with their participation were determined using X-ray and UV photoelectron spectroscopy (XPS, UPS). The results confirmed the formation of MgO compounds. Energy level diagrams were constructed for both systems. The valence band maximum of MgO layers was embedded deeper on the graphitized surface than on the SiC(0001).
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Zhang X, Zhao F, Wang Y, Liang X, Zhang Z, Feng Y, Li Y, Tang L, Feng W. Two-Dimensional GeTe: Air Stability and Photocatalytic Performance for Hydrogen Evolution. ACS Appl Mater Interfaces 2020; 12:37108-37115. [PMID: 32643918 DOI: 10.1021/acsami.0c08699] [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: 06/11/2023]
Abstract
As a key method to convert solar into chemical energy, photocatalytic water decomposition has garnered attention. Moreover, the development of graphene and graphene-like two-dimensional (2D) materials has brought fresh vitality in the field of photocatalysis. Here, we prepared two to four layers of GeTe nanosheets by ultrasonic-assisted liquid-phase exfoliation in argon and air, which we referred to as Ar-GeTe and O-GeTe, respectively. The photocatalytic hydrogen production potential of 2D GeTe was experimentally investigated for the first time. The results indicated that minimally layered GeTe samples are indirect-gap semiconductors with the GeTe band gap increasing after oxidation. All samples have suitable band positions that can drive photocatalytic water splitting into H2 under mild conditions, providing maximum hydrogen evolution rates of 1.13 mmol g-1 h-1 (Ar-GeTe) and 0.54 mmol g-1 h-1 (O-GeTe). With density functional theory computations, the structural stability of GeTe in air was discussed, revealing that oxygen atoms could easily combine with Ge to form a more stable structure, thus impacting the photocatalytic performance of 2D GeTe. Therefore, the light requirement and oxygen deficiency of the material give an advantage in the field of energy supply in space.
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Affiliation(s)
- Xin Zhang
- Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, P. R. China
| | - Fulai Zhao
- Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, P. R. China
| | - Yu Wang
- Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, P. R. China
| | - Xuejing Liang
- Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, P. R. China
| | - Zhixing Zhang
- Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, P. R. China
| | - Yiyu Feng
- Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, P. R. China
- Key Laboratory of Advanced Ceramics and Machining Technology, Ministry of Education, Tianjin 300072, P. R. China
- Key Laboratory of Materials Processing and Mold, Ministry of Education, Zhengzhou University, Zhengzhou 450002, China
| | - Yu Li
- Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, P. R. China
- Key Laboratory of Advanced Ceramics and Machining Technology, Ministry of Education, Tianjin 300072, P. R. China
| | - Lin Tang
- Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, P. R. China
- Key Laboratory of Advanced Ceramics and Machining Technology, Ministry of Education, Tianjin 300072, P. R. China
| | - Wei Feng
- Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, P. R. China
- Key Laboratory of Advanced Ceramics and Machining Technology, Ministry of Education, Tianjin 300072, P. R. China
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Wang LJ, Wang RL, Zhang X, Mu JL, Zhou ZY, Su ZM. Improved Photoreduction of CO 2 with Water by Tuning the Valence Band of Covalent Organic Frameworks. ChemSusChem 2020; 13:2973-2980. [PMID: 32017427 DOI: 10.1002/cssc.202000103] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Indexed: 06/10/2023]
Abstract
Porous covalent organic frameworks (COFs), as an emerging material, have the characteristics of high stability, large series of components, easy synthesis, modification, and adjustable amplitude. They have the potential to become good catalysts. Bromine, as a halogen, has attracted intensive interest for the modification of photocatalysts for photocatalytic reactions. It is feasible to enhance the activity and selectivity of the material by facile functionalization of the reticular parent structure's electron-withdrawing groups. In addition, the conjugation effect of bromine, further delocalizing the electrons of the COF, is beneficial to the progress of many photocatalytic reactions. Reports on the modification of COFs by bromine functional groups to improve the catalytic performance have not been found so far. Here, TAPP [5,10,15,20-tetrakis(4-aminophenyl)porphyrin] and 2,5-dibromo-1,4-benzenedialdehyde instead of terephthalaldehyde were chosen to synthesize a porphyrin-based COF (TAPBB-COF) by the solvothermal method. As expected, the valence band (VB) of TAPBB-COF is thus adjusted to a more suitable position. Additionally, the CO production when using TAPBB-COF under full-wavelength light for 12 h was 295.2 μmol g-1 , which was three times that of COF-366, and the new material has good recycling stability and selectivity (95.6 %). Theoretical calculations indicate that the nitrogen of the porphyrin ring and the Schiff base, and the bromine in TAPBB-COF contribute greatly to the activation of H2 O and the conversion of CO2 in the photoreaction.
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Affiliation(s)
- Lu-Jie Wang
- School of Chemistry and Chemical Engineering, Shandong University of Technology, Zibo, 255049, P. R. China
| | - Rui-Lei Wang
- School of Chemistry and Chemical Engineering, Shandong University of Technology, Zibo, 255049, P. R. China
| | - Xiao Zhang
- School of Chemistry and Chemical Engineering, Shandong University of Technology, Zibo, 255049, P. R. China
| | - Jing-Lin Mu
- School of Chemistry and Chemical Engineering, Shandong University of Technology, Zibo, 255049, P. R. China
| | - Zi-Yan Zhou
- School of Chemistry and Chemical Engineering, Shandong University of Technology, Zibo, 255049, P. R. China
| | - Zhong-Min Su
- School of Chemistry and Environmental Engineering, Changchun University of Science and Technology, Changchun, 130024, P. R. China
- College of Chemistry, Jilin University, Changchun, 130012, P. R. China
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Quijada C, Leite-Rosa L, Berenguer R, Bou-Belda E. Enhanced Adsorptive Properties and Pseudocapacitance of Flexible Polyaniline-Activated Carbon Cloth Composites Synthesized Electrochemically in a Filter-Press Cell. Materials (Basel) 2019; 12:E2516. [PMID: 31394840 DOI: 10.3390/ma12162516] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 07/22/2019] [Accepted: 08/01/2019] [Indexed: 11/16/2022]
Abstract
Electrochemical polymerization is known to be a suitable route to obtain conducting polymer-carbon composites uniformly covering the carbon support. In this work, we report the application of a filter-press electrochemical cell to polymerize polyaniline (PAni) on the surface of large-sized activated carbon cloth (ACC) by simple galvanostatic electropolymerization of an aniline-containing H2SO4 electrolyte. Flexible composites with different PAni loadings were synthesized by controlling the treatment time and characterized by means of Scanning Electron microscopy (SEM), X-Ray Photoelectron Spectroscopy (XPS), physical adsorption of gases, thermogravimetric analysis (TGA), cyclic voltammetry and direct current (DC) conductivity measurements. PAni grows first as a thin film mostly deposited inside ACC micro- and mesoporosity. At prolonged electropolymerization time, the amount of deposited PAni rises sharply to form a brittle and porous, thick coating of nanofibrous or nanowire-shaped structures. Composites with low-loading PAni thin films show enhanced specific capacitance, lower sheet resistance and faster adsorption kinetics of Acid Red 27. Instead, thick nanofibrous coatings have a deleterious effect, which is attributed to a dramatic decrease in the specific surface area caused by strong pore blockage and to the occurrence of contact electrical resistance. Our results demonstrate that mass-production restrictions often claimed for electropolymerization can be easily overcome.
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D'Amario L, Antila LJ, Pettersson Rimgard B, Boschloo G, Hammarström L. Kinetic Evidence of Two Pathways for Charge Recombination in NiO-Based Dye-Sensitized Solar Cells. J Phys Chem Lett 2015; 6:779-83. [PMID: 26262652 DOI: 10.1021/acs.jpclett.5b00048] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Mesoporous nickel oxide has been used as electrode material for p-type dye-sensitized solar cells (DSCs) for many years but no high efficiency cells have yet been obtained. One of the main issues that lowers the efficiency is the poor fill factor, for which a clear reason is still missing. In this paper we present the first evidence for a relation between applied potential and the charge recombination rate of the NiO electrode. In particular, we find biphasic recombination kinetics: a fast (15 ns) pathway attributed to the reaction with the holes in the valence band and a slow (1 ms) pathway assigned to the holes in the trap states. The fast component is the most relevant at positive potentials, while the slow component becomes more important at negative potentials. This means that at the working condition of the cell, the fast recombination is the most important. This could explain the low fill factor of NiO-based DSCs.
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Affiliation(s)
- Luca D'Amario
- Department of Chemistry - Ångström Laboratory, Uppsala University, Box 523, 751 20 Uppsala, Sweden
| | - Liisa J Antila
- Department of Chemistry - Ångström Laboratory, Uppsala University, Box 523, 751 20 Uppsala, Sweden
| | | | - Gerrit Boschloo
- Department of Chemistry - Ångström Laboratory, Uppsala University, Box 523, 751 20 Uppsala, Sweden
| | - Leif Hammarström
- Department of Chemistry - Ångström Laboratory, Uppsala University, Box 523, 751 20 Uppsala, Sweden
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Abstract
This Progress Report discusses the chemical sensitivity of Kβ valence to core X-ray emission spectroscopy (vtc-XES) and its applications for investigating 3d-transition-metal based materials. Vtc-XES can be used for ligand identification and for the characterization of the valence electronic levels. The technique provides information that is similar to valence band photoemission spectroscopy but the sample environment can be chosen freely and thus allows measurements in presence of gases and liquids and it can be applied for measurements under in situ/operando or extreme conditions. The theoretical basis of the technique is presented using a one-electron approach and the vtc-XES spectral features are interpreted using ground state density functional theory calculations. Some recent results obtained by vtc-XES in various scientific fields are discussed to demonstrate the potential and future applications of this technique. Resonant X-ray emission spectroscopy is briefly introduced with some applications for the study of 3d and 5d-transition-metal based systems.
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Affiliation(s)
- Erik Gallo
- ESRF - The European Synchrotron, 71 Avenue des Martyres, Grenoble, 38000, France
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Li J, Lv S, Liu Y, Bai J, Zhou B, Hu X. Photoeletrocatalytic activity of an n-ZnO/p-Cu2O/n-TNA ternary heterojunction electrode for tetracycline degradation. J Hazard Mater 2013; 262:482-488. [PMID: 24076571 DOI: 10.1016/j.jhazmat.2013.09.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 08/29/2013] [Accepted: 09/03/2013] [Indexed: 06/02/2023]
Abstract
In this study, a novel ternary heterojunction n-ZnO/p-Cu2O/n-TiO2 nanotube arrays (n-ZnO/p-Cu2O/n-TNA) nanophotocatalyst with a sandwich-like nanostructure was constructed and applied for the photoelectrocatalytic (PEC) degradation of typical PPCPs, tetracycline (TC). The ternary heterojunction n-ZnO/p-Cu2O/n-TNA was obtained by depositing Cu2O on the surface of TNA via sonoelectrochemical deposition (SED) and subsequently building a layer of ZnO onto the p-Cu2O/n-TNA surface through hydrothermal synthesis. After being deposited by the Cu2O, the absorption-band edge of the p-Cu2O/n-TNA was obviously red-shifted to the visible region (to 505 nm), and the band gap was reduced from its original 3.20 eV to 2.46 eV. The band gap absorption edge of the ternary n-ZnO/p-Cu2O/n-TNA is similar to that of p-Cu2O/n-TN and extends the visible spectrum absorption to 510 nm, corresponding to an Eg value of about 2.43 eV. Under illumination of visible light, the photocurrent density of the ternary heterojunction n-ZnO/p-Cu2O/n-TNA electrode at 0.5 V (vs. Ag/AgCl) was more than 106 times as high as that of the pure TNAs electrode, 3.6 times as high as that of the binary heterojunction p-Cu2O/n-TNA electrode. The degradation of TC indicated that the ternary heterojunction n-ZnO/p-Cu2O/n-TNA electrode maintained a very high photoelectrocatalytic activity and excellent stability and reliability. Such kind of ternary heterojunction electrode material has a broad application prospect not only in pollution control but also in many other fields.
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Affiliation(s)
- Jinhua Li
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, No. 800 Dongchuan Rd, Shanghai 200240, China
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Li J, Li J, Chen Q, Bai J, Zhou B. Converting hazardous organics into clean energy using a solar responsive dual photoelectrode photocatalytic fuel cell. J Hazard Mater 2013; 262:304-310. [PMID: 24051045 DOI: 10.1016/j.jhazmat.2013.08.066] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2013] [Revised: 08/07/2013] [Accepted: 08/25/2013] [Indexed: 06/02/2023]
Abstract
Direct discharging great quantities of organics into water-body not only causes serious environmental pollution but also wastes energy sources. In this paper, a solar responsive dual photoelectrode photocatalytic fuel cell (PFC(2)) based on TiO2/Ti photoanode and Cu2O/Cu photocathode was designed for hazardous organics treatment with simultaneous electricity generation. Under solar irradiation, the interior bias voltage produced for the Fermi level difference between photoelectrodes drives photoelectrons of TiO2/Ti photoanode to combine with photoholes of Cu2O/Cu photocathode through external circuit thus generating electricity. In the meantime, organics are decomposed by photoholes remained at TiO2/Ti photoanode. By using various hazardous organics including azo dyes as model pollutants, the PFC showed high converting performance of organics into electricity. For example, in 0.05 M phenol solution, a short-circuit current density 0.23 mA cm(-2), open-circuit voltage 0.49 V, maximum power output 0.3610(-4)W cm(-2) was achieved. On the other hand, removal rate of chroma reached 67%, 87% and 63% in 8h for methyl orange, methylene blue, Congo red, respectively.
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Affiliation(s)
- Jianyong Li
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, No. 800, Dongchuan Road, Shanghai 200240, China
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Tang J, Li Z, Ju J, Kumashiro R, A. Avila M, Suekuni K, Takabatake T, Guo F, Kobayashi K, Akai K, Tanigaki K. Soft x-ray photoelectron spectroscopy study of type-I clathrates. Sci Technol Adv Mater 2008; 9:044207. [PMID: 27878024 PMCID: PMC5099638 DOI: 10.1088/1468-6996/9/4/044207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2008] [Revised: 01/28/2009] [Accepted: 11/13/2008] [Indexed: 06/06/2023]
Abstract
Extensive soft x-ray photoelectron spectroscopy studies are performed on Ba8 Ga16 Ge30 (BGG) and Sr8Ga16Ge30 (SGG) single crystals ranging from Fermi to core levels, at a high-energy facility. Valence band x-ray photoelectron spectroscopy (XPS) experiments with theoretical calculations revealed that the valence band is mainly constructed by the Ge/Ga 4s and 4p wave functions with little contribution of the Ba/Sr atomic orbitals. Surprisingly, unexpected features evidencing the different shift for the 2a- and 6d- sites between Ba 4d and Sr 3d are observed. The detailed analyses including theoretical support by first-principles band-structure calculations lead to the conclusion that the component distributions of the larger tetrakaidecahedral cage are different depending on the endohedral atoms, which contrasts with the past consensus that BGG and SGG have the same framework structure. This may give thorough reconsiderations on earlier interpretations of experimental data.
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Affiliation(s)
- Jun Tang
- Department of Physics, Graduate School of Science, Tohoku University, 6-3 Aoba Aramaki Aoba-ku, Sendai, Miyagi 980-8578, Japan
| | - Zhaofei Li
- Department of Physics, Graduate School of Science, Tohoku University, 6-3 Aoba Aramaki Aoba-ku, Sendai, Miyagi 980-8578, Japan
| | - Jing Ju
- Department of Physics, Graduate School of Science, Tohoku University, 6-3 Aoba Aramaki Aoba-ku, Sendai, Miyagi 980-8578, Japan
| | - Ryotaro Kumashiro
- Department of Physics, Graduate School of Science, Tohoku University, 6-3 Aoba Aramaki Aoba-ku, Sendai, Miyagi 980-8578, Japan
| | - Marcos A. Avila
- Department of Quantum Matter, ADSM, Hiroshima University, Higashi-Hiroshima 739-8530, Japan
| | - Kouichirou Suekuni
- Department of Quantum Matter, ADSM, Hiroshima University, Higashi-Hiroshima 739-8530, Japan
| | - Toshiro Takabatake
- Department of Quantum Matter, ADSM, Hiroshima University, Higashi-Hiroshima 739-8530, Japan
| | - FangZhun Guo
- SPring-8, Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto Mikazuki-cho Sayo-gun Hyogo 679-5198, Japan
| | - Keisuke Kobayashi
- SPring-8, Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto Mikazuki-cho Sayo-gun Hyogo 679-5198, Japan
| | - Koji Akai
- MITC, Yamaguchi University, Tokiwadai 2-16-1, 755-8611 Ube, Japan
| | - Katsumi Tanigaki
- Department of Physics, Graduate School of Science, Tohoku University, 6-3 Aoba Aramaki Aoba-ku, Sendai, Miyagi 980-8578, Japan
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