1
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Seiß M, Lorenz J, Schmitz S, Moors M, Börner M, Monakhov KY. Synthesis and structures of cobalt-expanded zirconium- and cerium-oxo clusters as precursors for mixed-metal oxide thin films. Dalton Trans 2024; 53:8454-8462. [PMID: 38686658 DOI: 10.1039/d4dt00328d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
Transforming current complementary metal-oxide-semiconductor (CMOS) technology to fabricate memory chips and microprocessors into environmentally friendlier electronics requires the development of new approaches to resource- and energy-efficient electron transport and switching materials. Metal and multi-metal oxide layers play a key role in high-end technical applications. However, these layers are commonly produced through high-energy and high-temperature procedures. Herein, we demonstrate our first attempts to obtain stimuli-responsive mixed-metal oxide thin films from solution-processed molecular precursors under milder conditions. The molecular compounds of interest were prepared by one-pot reactions of a CoII carboxylate complex, triethylamine (Et3N), N-butyldiethanolamine (H2bda), and a hexanuclear complex [Ce6O4(OH)4(piv)12] (Hpiv = pivalic acid) or [Zr6O4(OH)4(ib)12(H2O)]·3Hib (Hib = isobutyric acid) in acetonitrile solution. The resulting charge-neutral, heterometallic coordination compounds display a ligand-supported pentanuclear {CeIV3CoIII2} core (in 1) and a dodecanuclear {ZrIV6CoII6} core (in 2), exhibiting thermal stability up to ca. 100 °C in air. Compound 2 was deposited and analyzed on Au(111) and SiO2/Si(100) surfaces to explore its potential as a single-molecule precursor for the preparation of atomically precise, complex mixed-metal oxide thin films. The adsorption characteristics of it demonstrate the ability to form stable agglomerates on the investigated surfaces.
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Affiliation(s)
- Maximilian Seiß
- Leibniz Institute of Surface Engineering (IOM), Permoserstraße 15, 04318 Leipzig, Germany.
- Institute for Inorganic Chemistry, Leipzig University, Johannisallee 29, 04103 Leipzig, Germany
| | - Jonas Lorenz
- Leibniz Institute of Surface Engineering (IOM), Permoserstraße 15, 04318 Leipzig, Germany.
| | - Sebastian Schmitz
- Leibniz Institute of Surface Engineering (IOM), Permoserstraße 15, 04318 Leipzig, Germany.
| | - Marco Moors
- Leibniz Institute of Surface Engineering (IOM), Permoserstraße 15, 04318 Leipzig, Germany.
| | - Martin Börner
- Institute for Inorganic Chemistry, Leipzig University, Johannisallee 29, 04103 Leipzig, Germany
| | - Kirill Yu Monakhov
- Leibniz Institute of Surface Engineering (IOM), Permoserstraße 15, 04318 Leipzig, Germany.
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2
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Laqdiem M, Garcia-Fayos J, Carrillo AJ, Almar L, Balaguer M, Fabuel M, Serra JM. Co 2MnO 4/Ce 0.8Tb 0.2O 2-δ Dual-Phase Membrane Material with High CO 2 Stability and Enhanced Oxygen Transport for Oxycombustion Processes. ACS Appl Energy Mater 2024; 7:302-311. [PMID: 38213555 PMCID: PMC10777685 DOI: 10.1021/acsaem.3c02606] [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: 10/15/2023] [Revised: 11/29/2023] [Accepted: 11/29/2023] [Indexed: 01/13/2024]
Abstract
Oxygen transport membranes (OTMs) are a promising oxygen production technology with high energy efficiency due to the potential for thermal integration. However, conventional perovskite materials of OTMs are unstable in CO2 atmospheres, which limits their applicability in oxycombustion processes. On the other hand, some dual-phase membranes are stable in CO2 and SO2 without permanent degradation. However, oxygen permeation is still insufficient; therefore, intensive research focuses on boosting oxygen permeation. Here, we present a novel dual-phase membrane composed of an ion-conducting fluorite phase (Ce0.8Tb0.2O2-δ, CTO) and an electronic-conducting spinel phase (Co2MnO4, CMO). CMO spinel exhibits high electronic conductivity (60 S·cm-1 at 800 °C) compared to other spinels used in dual-phase membranes, i.e., 230 times higher than that of NiFe2O4 (NFO). This higher conductivity ameliorates gas-solid surface exchange and bulk diffusion mechanisms. By activating the bulk membrane with a CMO/CTO porous catalytic layer, it was possible to achieve an oxygen flux of 0.25 mL·min-1·cm-2 for the 40CMO/60CTO (%vol), 680 μm-thick membrane at 850 °C even under CO2-rich environments. This dual-phase membrane shows excellent potential as an oxygen transport membrane or oxygen electrode under high CO2 and oxycombustion operation.
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Affiliation(s)
- Marwan Laqdiem
- Instituto de Tecnología
Química (Universitat Politècnica de València
− Consejo Superior de Investigaciones Científicas), Av. Los Naranjos s/n, E-46022 Valencia, Spain
| | - Julio Garcia-Fayos
- Instituto de Tecnología
Química (Universitat Politècnica de València
− Consejo Superior de Investigaciones Científicas), Av. Los Naranjos s/n, E-46022 Valencia, Spain
| | - Alfonso J. Carrillo
- Instituto de Tecnología
Química (Universitat Politècnica de València
− Consejo Superior de Investigaciones Científicas), Av. Los Naranjos s/n, E-46022 Valencia, Spain
| | - Laura Almar
- Instituto de Tecnología
Química (Universitat Politècnica de València
− Consejo Superior de Investigaciones Científicas), Av. Los Naranjos s/n, E-46022 Valencia, Spain
| | - María Balaguer
- Instituto de Tecnología
Química (Universitat Politècnica de València
− Consejo Superior de Investigaciones Científicas), Av. Los Naranjos s/n, E-46022 Valencia, Spain
| | - María Fabuel
- Instituto de Tecnología
Química (Universitat Politècnica de València
− Consejo Superior de Investigaciones Científicas), Av. Los Naranjos s/n, E-46022 Valencia, Spain
| | - José M. Serra
- Instituto de Tecnología
Química (Universitat Politècnica de València
− Consejo Superior de Investigaciones Científicas), Av. Los Naranjos s/n, E-46022 Valencia, Spain
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3
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Mason JL, Huizenga CD, Ray M, Kafader JO, Jarrold CC. Electronic Structure of Heteronuclear Cerium-Platinum Clusters. J Phys Chem A 2023; 127:6749-6763. [PMID: 37531463 DOI: 10.1021/acs.jpca.3c03738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/04/2023]
Abstract
Beyond the now well-known strong catalyst-support interactions reported for ceria-supported platinum catalysts, intermetallic Ce-Pt compounds exhibit fascinating properties such as heavy fermion behavior and magnetic instability. Small heterometallic Ce-Pt clusters, which can provide insights into the local features that govern bulk phenomena, have been less explored. Herein, the anion photoelectron spectra of three small mixed Ce-Pt clusters, Ce2OPt-, Ce2Pt-, and Ce3Pt-, are presented and interpreted with supporting density functional theory calculations. The calculations, which are readily reconciled with the experimental spectra, suggest the presence of numerous close-lying spin states, including states in which the Ce 4f electrons are ferromagnetically coupled or antiferromagnetically coupled. The Pt center is consistently in a nominal -2 charge state in all cluster neutrals and anions, giving the Ce-Pt bond ionic character. Ce-Pt bonds are stronger than Ce-Ce bonds, and the O atom in Ce2OPt- coordinates only with the Ce centers. The energy of the singly occupied Ce-local 4f orbitals relative to the Pt-local orbitals changes with cluster composition. Discussion of the results includes potential implications for Ce-rich intermetallic materials.
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Affiliation(s)
- Jarrett L Mason
- Department of Chemistry, Indiana University, 800 E. Kirkwood Ave, Bloomington, Indiana 47405, United States
| | - Caleb D Huizenga
- Department of Chemistry, Indiana University, 800 E. Kirkwood Ave, Bloomington, Indiana 47405, United States
| | - Manisha Ray
- Department of Chemistry, Indiana University, 800 E. Kirkwood Ave, Bloomington, Indiana 47405, United States
| | - Jared O Kafader
- Department of Chemistry, Indiana University, 800 E. Kirkwood Ave, Bloomington, Indiana 47405, United States
| | - Caroline Chick Jarrold
- Department of Chemistry, Indiana University, 800 E. Kirkwood Ave, Bloomington, Indiana 47405, United States
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4
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Solovyev A, Shipilova A, Smolyanskiy E. Solid Oxide Fuel Cells with Magnetron Sputtered Single-Layer SDC and Multilayer SDC/YSZ/SDC Electrolytes. Membranes (Basel) 2023; 13:585. [PMID: 37367789 DOI: 10.3390/membranes13060585] [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: 05/19/2023] [Revised: 06/01/2023] [Accepted: 06/03/2023] [Indexed: 06/28/2023]
Abstract
Samarium-doped ceria (SDC) is considered as an alternative electrolyte material for intermediate-temperature solid oxide fuel cells (IT-SOFCs) because its conductivity is higher than that of commonly used yttria-stabilized zirconia (YSZ). The paper compares the properties of anode-supported SOFCs with magnetron sputtered single-layer SDC and multilayer SDC/YSZ/SDC thin-film electrolyte, with the YSZ blocking layer 0.5, 1, and 1.5 μm thick. The thickness of the upper and lower SDC layers of the multilayer electrolyte are constant and amount to 3 and 1 μm, respectively. The thickness of single-layer SDC electrolyte is 5.5 μm. The SOFC performance is studied by measuring current-voltage characteristics and impedance spectra in the range of 500-800 °C. X-ray diffraction and scanning electron microscopy are used to investigate the structure of the deposited electrolyte and other fuel cell layers. SOFCs with the single-layer SDC electrolyte show the best performance at 650 °C. At this temperature, open circuit voltage and maximum power density are 0.8 V and 651 mW/cm2, respectively. The formation of the SDC electrolyte with the YSZ blocking layer improves the open circuit voltage up to 1.1 V and increases the maximum power density at the temperatures over 600 °C. It is shown that the optimal thickness of the YSZ blocking layer is 1 µm. The fuel cell with the multilayer SDC/YSZ/SDC electrolyte, with the layer thicknesses of 3/1/1 µm, has the maximum power density of 2263 and 1132 mW/cm2 at 800 and 650 °C, respectively.
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Affiliation(s)
- Andrey Solovyev
- Institute of High Current Electronics SB RAS, 634055 Tomsk, Russia
| | - Anna Shipilova
- Institute of High Current Electronics SB RAS, 634055 Tomsk, Russia
- Department of Physics, National Research Tomsk State University, 634050 Tomsk, Russia
| | - Egor Smolyanskiy
- School of Advanced Manufacturing Technologies, National Research Tomsk Polytechnic University, 634050 Tomsk, Russia
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5
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Appu M, Wu H, Chen H, Huang J. Tea polyphenols mediated biogenic synthesis of chitosan-coated cerium oxide (CS/CeO 2) nanocomposites and their potent antimicrobial capabilities. Environ Sci Pollut Res Int 2023; 30:42575-42586. [PMID: 35233667 DOI: 10.1007/s11356-022-19349-x] [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] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 02/18/2022] [Indexed: 06/14/2023]
Abstract
In the present study, we hypothesized that novel nanocomposites of chitosan-coated cerium oxide (CS/CeO2 NCs) derived from aqueous extracts of tea polyphenols would be stabilized and reduced by using green chemistry. The UV-visible spectrum of the synthesized material revealed an SPR peak at 279 nm, and the morphological characteristics of nanoparticles (NPs) as a uniformly distributed spherical shape with a size range of 20 nm were confirmed by field emission scanning electron microscopy (FESEM). The Fourier transform infrared spectroscopy (FTIR) spectrum illustrated the amino groups of chitosan-coated with CeO2 NPs on the surface. While, the hydrodynamic size (376 nm) and surface charge (+ 25.0 mV) of particles were assessed by dynamic light scattering (DLS), and the existence of oxidation state elements Ce 3d, O 1 s, and C 1 s was identified by employing X-ray photoelectron spectroscopy (XPS). A cubic fluorite polycrystalline structure with a crystallite size of (5.24 nm) NPs was determined using an X-ray Diffractometer (XRD). The developed CS/CeO2 NCs demonstrated excellent antibacterial and antifungal efficacy against foodborne pathogens such as Escherichia coli, Staphylococcus aureus, and Botrytis cinerea with zone of inhibition of 13.5 ± 0.2 and 11.7 ± 0.2 mm, respectively. The results elucidated the potential of biosynthesized CS/CeO2 NCs could be utilized as potent antimicrobial agents in the food and agriculture industries.
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Affiliation(s)
- Manikandan Appu
- College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, 310035, People's Republic of China
| | - Huixiang Wu
- College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, 310035, People's Republic of China
| | - Hao Chen
- College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, 310035, People's Republic of China
| | - Jianying Huang
- College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, 310035, People's Republic of China.
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6
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Kalaev D, Tuller HL. Simultaneous electrical impedance and optical absorption spectroscopy for rapid characterization of oxygen vacancies and small polarons in doped ceria. Phys Chem Chem Phys 2023; 25:5731-5742. [PMID: 36744370 DOI: 10.1039/d2cp04901e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Mixed ionic-electronic conductors (MIECs) play a central role in emerging energy conversion and energy efficient computational technologies. However, it is both challenging and resource demanding to characterize MIECs over the broad range of experimental conditions of interest, thereby significantly limiting their study and applications. Here, a novel method of a simultaneous measurement of electrical conductivity and optical absorption of thin films in out-of-equilibrium state, i.e. during a reduction process, is employed for a comprehensive study of a MIEC oxide, PrxCe1-xO2-δ (PCO). It enables, orders of magnitude faster than by established techniques, characterization of the oxygen vacancy and small polaron formation and transport as a function of temperature (demonstrated here down to 200 °C), in a wide range of deviation from stoichiometry, δ. For instance, at 600 °C the PCO properties were obtained during a ten minute reduction process, in the pO2 range from 1 to 10-13 bar. The experimental results show that the oxygen vacancy mobility is constant while the small polaron mobility is linear in δ, in the whole pO2 range, which yields the total conductivity quadratic in δ. Furthermore, the method was applied to study the modification of PCO's transport properties with composition change. It was shown that increasing x from 0.1 to 0.2 suppresses the ionic mobility and, at the same time, enhances the small polaron mobility. Finally, the optically determined δ was used to define an instantaneous oxygen activity in PCO that can be accessed in the out-of-equilibrium experiments. This work opens up new possibilities to study the effects of microstructure, strain and other applied external stimuli on the transport and thermodynamic properties of PCO and similar types of MIEC materials.
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Affiliation(s)
- D Kalaev
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
| | - H L Tuller
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
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7
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Wu T, Vegge T, Anton Hansen H. Trends in High-Temperature H2 Production on CeO2 Co-Doped with Trivalent Cations in Solid Oxide Electrolysis Cells. J Catal 2023. [DOI: 10.1016/j.jcat.2023.02.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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8
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Sun J, Kang S, Kim J, Min K. Accelerated Discovery of Novel Garnet-Type Solid-State Electrolyte Candidates via Machine Learning. ACS Appl Mater Interfaces 2023; 15:5049-5057. [PMID: 36654192 DOI: 10.1021/acsami.2c15980] [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: 06/17/2023]
Abstract
All-solid-state batteries (ASSBs) have attracted considerable attention because of their higher energy density and stability than conventional lithium-ion batteries (LIBs). For the development of promising ASSBs, solid-state electrolytes (SSEs) are essential to achieve structural integrity. Thus, in this study, a machine-learning-based surrogate model was developed to search for ideal garnet-type SSE candidates. The well-known Li7La3Zr2O12 structure was used as a base material, and 73 chemical elements were substituted on La and Zr sites, leading to 5329 potential structures. First, the elasticity database and machine learning descriptors were adopted from previous studies. Subsequently, the machine-learning-based surrogate model was applied to predict the elastic properties of potential SSE materials, followed by first-principles calculations for validation. Furthermore, the active learning process demonstrated that it can effectively decrease prediction uncertainty. Finally, the ionic conductivity of the mechanically superior materials was predicted to suggest optimal SSE candidates. Then, ab initio molecular dynamics simulations are followed for confirmation of diffusion behavior for materials classified as superionic; 10 new tetragonal-phase garnet SSEs are verified with superior mechanical and ionic conductivity properties. We believe that the current model and the constructed database will become a cornerstone for the development of next-generation SSE materials.
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Affiliation(s)
- Jiwon Sun
- School of Mechanical Engineering, Soongsil University, 369 Sangdo-ro, Dongjak-gu, Seoul 06978, Republic of Korea
| | - Seungpyo Kang
- School of Mechanical Engineering, Soongsil University, 369 Sangdo-ro, Dongjak-gu, Seoul 06978, Republic of Korea
| | - Joonchul Kim
- School of Mechanical Engineering, Soongsil University, 369 Sangdo-ro, Dongjak-gu, Seoul 06978, Republic of Korea
| | - Kyoungmin Min
- School of Mechanical Engineering, Soongsil University, 369 Sangdo-ro, Dongjak-gu, Seoul 06978, Republic of Korea
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9
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Fleming CL, Wong J, Golzan M, Gunawan C, McGrath KC. Insights from a Bibliometrics-Based Analysis of Publishing and Research Trends on Cerium Oxide from 1990 to 2020. Int J Mol Sci 2023; 24. [PMID: 36768372 DOI: 10.3390/ijms24032048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 12/29/2022] [Accepted: 12/29/2022] [Indexed: 01/21/2023] Open
Abstract
The purpose of this study is to evaluate the literature for research trends on cerium oxide from 1990 to 2020 and identify gaps in knowledge in the emerging application(s) of CeONP. Bibliometric methods were used to identify themes in database searches from PubMed, Scopus and Web of Science Core Collection using SWIFT-Review, VOSviewer and SciMAT software programs. A systematic review was completed on published cerium oxide literature extracted from the Scopus database (n = 17,115), identifying themes relevant to its industrial, environmental and biomedical applications. A total of 172 publications were included in the systematic analysis and categorized into four time periods with research themes identified; "doping additives" (n = 5, 1990-1997), "catalysts" (n = 32, 1998-2005), "reactive oxygen species" (n = 66, 2006-2013) and "pathology" (n = 69, 2014-2020). China and the USA showed the highest number of citations and publications for cerium oxide research from 1990 to 2020. Longitudinal analysis showed CeONP has been extensively used for various applications due to its catalytic properties. In conclusion, this study showed the trend in research in CeONP over the past three decades with advancements in nanoparticle engineering like doping, and more recently surface modification or functionalization to further enhanced its antioxidant abilities. As a result of recent nanoparticle engineering developments, research into CeONP biological effects have highlighted its therapeutic potential for a range of human pathologies such as Alzheimer's disease. Whilst research over the past three decades show the versatility of cerium oxide in industrial and environmental applications, there are still research opportunities to investigate the potential beneficial effects of CeONP in its application(s) on human health.
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10
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Zhang X, Zhu L, Hou Q, Guan J, Lu Y, Keal TW, Buckeridge J, Catlow CRA, Sokol AA. Toward a Consistent Prediction of Defect Chemistry in CeO 2. Chem Mater 2023; 35:207-227. [PMID: 36644213 PMCID: PMC9835833 DOI: 10.1021/acs.chemmater.2c03019] [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] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 11/25/2022] [Indexed: 05/10/2023]
Abstract
Polarizable shell-model potentials are widely used for atomic-scale modeling of charged defects in solids using the Mott-Littleton approach and hybrid Quantum Mechanical/Molecular Mechanical (QM/MM) embedded-cluster techniques. However, at the pure MM level of theory, the calculated defect energetics may not satisfy the requirement of quantitative predictions and are limited to only certain charged states. Here, we proposed a novel interatomic potential development scheme that unifies the predictions of all relevant charged defects in CeO2 based on the Mott-Littleton approach and QM/MM electronic-structure calculations. The predicted formation energies of oxygen vacancies accompanied by different excess electron localization patterns at the MM level of theory reach the accuracy of density functional theory (DFT) calculations using hybrid functionals. The new potential also accurately reproduces a wide range of physical properties of CeO2, showing excellent agreement with experimental and other computational studies. These findings provide opportunities for accurate large-scale modeling of the partial reduction and nonstoichiometry in CeO2, as well as a prototype for developing robust interatomic potentials for other defective crystals.
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Affiliation(s)
- Xingfan Zhang
- Kathleen
Lonsdale Materials Chemistry, Department of Chemistry, University College London, LondonWC1H 0AJ, United Kingdom
| | - Lei Zhu
- Kathleen
Lonsdale Materials Chemistry, Department of Chemistry, University College London, LondonWC1H 0AJ, United Kingdom
| | - Qing Hou
- Kathleen
Lonsdale Materials Chemistry, Department of Chemistry, University College London, LondonWC1H 0AJ, United Kingdom
- Institute
of Photonic Chips, University of Shanghai
for Science and Technology, Shanghai200093, China
| | - Jingcheng Guan
- Kathleen
Lonsdale Materials Chemistry, Department of Chemistry, University College London, LondonWC1H 0AJ, United Kingdom
| | - You Lu
- Scientific
Computing Department, STFC Daresbury Laboratory, Warrington, CheshireWA4 4AD, United Kingdom
| | - Thomas W. Keal
- Scientific
Computing Department, STFC Daresbury Laboratory, Warrington, CheshireWA4 4AD, United Kingdom
| | - John Buckeridge
- School
of Engineering, London South Bank University, LondonSE1 OAA, United Kingdom
| | - C. Richard A. Catlow
- Kathleen
Lonsdale Materials Chemistry, Department of Chemistry, University College London, LondonWC1H 0AJ, United Kingdom
- School
of Chemistry, Cardiff University, Park Place, CardiffCF10 1AT, United
Kingdom
| | - Alexey A. Sokol
- Kathleen
Lonsdale Materials Chemistry, Department of Chemistry, University College London, LondonWC1H 0AJ, United Kingdom
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11
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Das D, Prakash J, Goutam UK, Manna S, Gupta SK, Sudarshan K. Oxygen vacancy and valence engineering in CeO 2 through distinct sized ion doping and their impact on oxygen reduction reaction catalysis. Dalton Trans 2022; 51:18572-18582. [PMID: 36444845 DOI: 10.1039/d2dt03198a] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Defect tuning in ceria to enhance its catalytic properties is a subject of great interest for the scientific community owing to the growing demand for catalytic materials in drug, automobile and chemical industries. Doping induced defect engineering was found to be one of the most sought out strategies particularly in oxides for achieving multifunctionality. Here, in this study, we have doped ceria with distinct sized trivalent rare-earth ions, namely, Y3+, Eu3+ and La3+, using combustion techniques. Positron annihilation lifetime spectroscopy (PALS) suggested enhanced defect density with doping in general and higher concentration of oxygen vacancies in La3+ doped ceria compared to Y3+ and Eu3+ counterparts. X-ray photoelectron spectroscopy (XPS) suggested the existence of both Ce3+ and Ce4+, with the former having higher fraction in CeO2:La3+ compared to CeO2:Y3+. The electron transfer resistance (Rct) reduced in all the doped samples when compared to undoped ceria and they demonstrated improved catalytic activity towards the oxygen reduction reaction (ORR). The highest reduction in Rct was seen in the 5% La doped sample owing to the very high concentration of oxygen vacancies and Ce3+/Ce4+ ratio and CeO2:5.0% La3+ showed the best performance towards ORR electrocatalysis. The studies are expected to help in further tuning the catalysts in terms of dopant concentrations, and in future work, the strategy will be to control the Ce3+/Ce4+ ratio and see its implication in both catalytic and magnetic applications.
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Affiliation(s)
- Debarati Das
- Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai-400085, India. .,Homi Bhabha National Institute, Anushaktinagar, Mumbai-400094, India
| | - Jyoti Prakash
- Homi Bhabha National Institute, Anushaktinagar, Mumbai-400094, India.,Materials Group, Bhabha Atomic Research Centre, Mumbai-400085, India
| | - U K Goutam
- Technical Physics Division, Bhabha Atomic Research Centre, Mumbai-400085, India
| | - S Manna
- Homi Bhabha National Institute, Anushaktinagar, Mumbai-400094, India.,Analytical Chemistry Division, Bhabha Atomic Research Centre, Mumbai-400085, India
| | - Santosh K Gupta
- Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai-400085, India. .,Homi Bhabha National Institute, Anushaktinagar, Mumbai-400094, India
| | - K Sudarshan
- Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai-400085, India. .,Homi Bhabha National Institute, Anushaktinagar, Mumbai-400094, India
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12
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Lee J, Nikam RD, Kwak M, Hwang H. Strategies to Improve the Synaptic Characteristics of Oxygen-Based Electrochemical Random-Access Memory Based on Material Parameters Optimization. ACS Appl Mater Interfaces 2022; 14:13450-13457. [PMID: 35257578 DOI: 10.1021/acsami.1c21045] [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] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Oxygen-based electrochemical random-access memories (O-ECRAMs) are promising synaptic devices for neuromorphic applications because of their near-ideal synaptic characteristics and compatibility with complementary metal-oxide-semiconductor processes. However, the correlation between material parameters and synaptic properties of O-ECRAM devices has not yet been elucidated. Here, we propose the critical design parameters to fabricate an ideal ECRAM device. Based on the experimental data and simulation results, it is revealed that consistent ion supply from the electrolyte and rapid ion diffusion in the channel are critical factors for ideal synaptic characteristics. To optimize these parameters, crystalline WO2.7 exhibiting fast ion diffusivity and ZrO1.7 exhibiting an appropriate ion conduction energy barrier (1.1 eV) are used as a channel and an electrolyte, respectively. As a result, synaptic characteristics with near-ideal weight-update linearity in the nanosiemens conductance range are achieved. Finally, a selector-less O-ECRAM device is integrated into a 2 × 2 array, and high recognition accuracy (94.83%) of the Modified National Institute of Standards and Technology pattern is evaluated.
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Affiliation(s)
- Jongwon Lee
- Center for Single-Atom-based Semiconductor Devices and Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea
| | - Revannath Dnyandeo Nikam
- Center for Single-Atom-based Semiconductor Devices and Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea
| | - Myonghoon Kwak
- Center for Single-Atom-based Semiconductor Devices and Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea
| | - Hyunsang Hwang
- Center for Single-Atom-based Semiconductor Devices and Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea
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Righi G, Benedetti S, Magri R. Investigation of the structural and electronic differences between silver and copper doped ceria using the density functional theory. J Phys Condens Matter 2022; 34:204010. [PMID: 35213842 DOI: 10.1088/1361-648x/ac58d9] [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: 10/06/2021] [Accepted: 02/25/2022] [Indexed: 06/14/2023]
Abstract
Using the density functional theory (DFT) we have investigated how Ag and Cu atoms, substitutional to Ce, arrange themselves within Ceria (CeO2) and their effect on the ceria lattice, the oxidation states of the metal atoms, and the oxygen vacancy formation energies. Noble metal doped ceria has been proposed in substitution of platinum for a number of catalytic reactions. We have considered single noble metal atoms substituting Ce atoms in the (111) CeO2surface unit cell, and investigated the thermodynamic stability of few configurations of one, two, and four Ag or Cu atoms in the unit cell. We have found that the noble metal atoms prefer to be located in the cation layer closer to the surface. An interesting result is that Cu causes a strong lattice distortion contrary to Ag. Ag, instead, causes a stronger reduction (oxygen loss) than Cu, since the electrons released in the oxygen vacancy formation are transferred mainly to Ag atoms, whose oxidation state tends towards +1, their preferred one, as found experimentally. In the Cu doped ceria, instead, part of the electrons reduces cerium atoms from +4 to +3 since Cu tends to stay in the +2 oxidation state, its preferred one. When we increase the concentration of Ag and Cu, substituting four Ce atoms, the noble metal atoms prefer to sit closer to each other, forming structural motifs resembling those typical of the Ag2O and CuO oxides.
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Affiliation(s)
- Giulia Righi
- Consiglio Nazionale delle Ricerche, Istituto Officina dei Materiali, CNR-IOM c/o SISSA, 34136 Trieste, Italy
| | - Sara Benedetti
- Department of Physics, Informatics, and Mathematics of the University of Modena and Reggio-Emilia, Italy
| | - Rita Magri
- Department of Physics, Informatics, and Mathematics of the University of Modena and Reggio-Emilia, Italy
- CNR-S3 Institute of Nanoscience, via Campi 213/A, 41100 Modena, Italy
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14
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Abstract
Reversible solid oxide fuel cell (RSOFC) is an energy device that flexibly interchanges between electrical and chemical energy according to people's life and production needs. The development of cell materials affects the stability and cost of the cell, but also restricts its market-oriented development. After decades of research by scientists, a lot of achievements and progress have been made on RSOFC materials. According to the composition and requirements of each component of RSOFC, this article summarizes the research progress based on materials and discusses the merits and demerits of current cell materials in electrochemical performance. According to the efficiency of different materials in solid oxide fuel cell (SOFC mode) and solid oxide electrolyzer (SOEC mode), the challenges encountered by RSOFC in the operation are evaluated, and the future development of RSOFC materials is boldly prospected.
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Affiliation(s)
- Minghai Shen
- College of Health Science and Environmental Engineering, Shenzhen Technology University, Shenzhen 518118, China
- School of Chemical and Environmental Engineering, China University of Mining & Technology (Beijing), Beijing 100083, China
| | - Fujin Ai
- College of Health Science and Environmental Engineering, Shenzhen Technology University, Shenzhen 518118, China
| | - Hailing Ma
- Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield S1 3JD, UK
| | - Hui Xu
- School of Chemical and Environmental Engineering, China University of Mining & Technology (Beijing), Beijing 100083, China
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15
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Zhang L, Ji W, Guo Q, Cheng Y, Liu X, Lu H, Dai H. Probing into the In-Situ Exsolution Mechanism of Metal Nanoparticles from Doped Ceria Host. Nanomaterials (Basel) 2021; 11:2114. [PMID: 34443943 PMCID: PMC8398560 DOI: 10.3390/nano11082114] [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] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 08/16/2021] [Accepted: 08/18/2021] [Indexed: 11/16/2022]
Abstract
Exsolved nanoparticle catalysts have recently attracted broad research interest as they simultaneously combine the features of catalytic activity and chemical stability in various applications of energy conversion and storage. As the internal mechanism of in-situ exsolution is of prime significance for the optimization of its strategy, comprehensive research focused on the behaviors of in-situ segregation for metal (Mn, Fe, Co, Ni, Cu, Ag, Pt and Au)-substituted CeO2 is reported using first-principles calculations. An interesting link between the behaviors of metal growth from the ceria host and their microelectronic reconfigurations was established to understand the inherent attribute of metal self-regeneration, where a stair-stepping charge difference served as the inner driving force existing along the exsolving pathway, and the weak metal-coordinate associations synergistically facilitate the ceria's in-situ growth. We hope that these new insights provide a microscopic insight into the physics of in-situ exsolution to gain a guideline for the design of nanoparticle socketed catalysts from bottom to top.
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Affiliation(s)
- Lifang Zhang
- School of Chemistry and Chemical Engineering, Nantong University, Nantong 226009, China; (L.Z.); (W.J.); (Q.G.)
| | - Weiwei Ji
- School of Chemistry and Chemical Engineering, Nantong University, Nantong 226009, China; (L.Z.); (W.J.); (Q.G.)
| | - Qiyang Guo
- School of Chemistry and Chemical Engineering, Nantong University, Nantong 226009, China; (L.Z.); (W.J.); (Q.G.)
| | - Yu Cheng
- School of Chemistry and Chemical Engineering, Nantong University, Nantong 226009, China; (L.Z.); (W.J.); (Q.G.)
| | - Xiaojuan Liu
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China;
- University of Science and Technology of China, Hefei 230026, China
| | - Hongbin Lu
- School of Chemistry and Chemical Engineering, Nantong University, Nantong 226009, China; (L.Z.); (W.J.); (Q.G.)
| | - Hong Dai
- School of Chemistry and Chemical Engineering, Nantong University, Nantong 226009, China; (L.Z.); (W.J.); (Q.G.)
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16
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Pikalova EY, Kalinina EG. Solid oxide fuel cells based on ceramic membranes with mixed conductivity: improving efficiency. Russ Chem Rev 2021. [DOI: 10.1070/rcr4966] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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17
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Polychronopoulou K, AlKhoori AA, Efstathiou AM, Jaoude MA, Damaskinos CM, Baker MA, Almutawa A, Anjum DH, Vasiliades MA, Belabbes A, Vega LF, Zedan AF, Hinder SJ. Design Aspects of Doped CeO 2 for Low-Temperature Catalytic CO Oxidation: Transient Kinetics and DFT Approach. ACS Appl Mater Interfaces 2021; 13:22391-22415. [PMID: 33834768 PMCID: PMC8153538 DOI: 10.1021/acsami.1c02934] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
CO elimination through oxidation over highly active and cost-effective catalysts is a way forward for many processes of industrial and environmental importance. In this study, doped CeO2 with transition metals (TM = Cu, Co, Mn, Fe, Ni, Zr, and Zn) at a level of 20 at. % was tested for CO oxidation. The oxides were prepared using microwave-assisted sol-gel synthesis to improve catalyst's performance for the reaction of interest. The effect of heteroatoms on the physicochemical properties (structure, morphology, porosity, and reducibility) of the binary oxides M-Ce-O was meticulously investigated and correlated to their CO oxidation activity. It was found that the catalytic activity (per gram basis or TOF, s-1) follows the order Cu-Ce-O > Ce-Co-O > Ni-Ce-O > Mn-Ce-O > Fe-Ce-O > Ce-Zn-O > CeO2. Participation of mobile lattice oxygen species in the CO/O2 reaction does occur, the extent of which is heteroatom-dependent. For that, state-of-the-art transient isotopic 18O-labeled experiments involving 16O/18O exchange followed by step-gas CO/Ar or CO/O2/Ar switches were used to quantify the contribution of lattice oxygen to the reaction. SSITKA-DRIFTS studies probed the formation of carbonates while validating the Mars-van Krevelen (MvK) mechanism. Scanning transmission electron microscopy-high-angle annular dark field imaging coupled with energy-dispersive spectroscopy proved that the elemental composition of dopants in the individual nanoparticle of ceria is less than their composition at a larger scale, allowing the assessment of the doping efficacy. Despite the similar structural features of the catalysts, a clear difference in the Olattice mobility was also found as well as its participation (as expressed with the α descriptor) in the reaction, following the order αCu > αCo> αMn > αZn. Kinetic studies showed that it is rather the pre-exponential (entropic) factor and not the lowering of activation energy that justifies the order of activity of the solids. DFT calculations showed that the adsorption of CO on the Cu-doped CeO2 surface is more favorable (-16.63 eV), followed by Co, Mn, Zn (-14.46, -4.90, and -4.24 eV, respectively), and pure CeO2 (-0.63 eV). Also, copper compensates almost three times more charge (0.37e-) compared to Co and Mn, ca. 0.13e- and 0.10e-, respectively, corroborating for its tendency to be reduced. Surface analysis (X-ray photoelectron spectroscopy), apart from the oxidation state of the elements, revealed a heteroatom-ceria surface interaction (Oa species) of different extents and of different populations of Oa species.
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Affiliation(s)
- Kyriaki Polychronopoulou
- Department
of Mechanical Engineering, Khalifa University
of Science and Technology, Main Campus, Abu Dhabi 127788, UAE
- Center
for Catalysis and Separations, Khalifa University
of Science and Technology, Main Campus, Abu Dhabi 127788, UAE
| | - Ayesha A. AlKhoori
- Department
of Mechanical Engineering, Khalifa University
of Science and Technology, Main Campus, Abu Dhabi 127788, UAE
- Center
for Catalysis and Separations, Khalifa University
of Science and Technology, Main Campus, Abu Dhabi 127788, UAE
| | - Angelos M. Efstathiou
- Department
of Chemistry, Heterogeneous Catalysis Lab, University of Cyprus, 1 University Avenue, University Campus, 2109 Nicosia, Cyprus
| | - Maguy Abi Jaoude
- Center
for Catalysis and Separations, Khalifa University
of Science and Technology, Main Campus, Abu Dhabi 127788, UAE
- Department
of Chemistry, Khalifa University of Science
and Technology, Main
Campus, Abu Dhabi 127788, UAE
| | - C. M. Damaskinos
- Department
of Chemistry, Heterogeneous Catalysis Lab, University of Cyprus, 1 University Avenue, University Campus, 2109 Nicosia, Cyprus
| | - Mark A. Baker
- The
Surface Analysis Laboratory, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 4DL, U.K.
| | - Alia Almutawa
- Department
of Mechanical Engineering, Khalifa University
of Science and Technology, Main Campus, Abu Dhabi 127788, UAE
| | - Dalaver H. Anjum
- Center
for Catalysis and Separations, Khalifa University
of Science and Technology, Main Campus, Abu Dhabi 127788, UAE
- Department
of Physics, Khalifa University of Science
and Technology, Main
Campus, Abu Dhabi 127788, UAE
| | - Michalis A. Vasiliades
- Department
of Chemistry, Heterogeneous Catalysis Lab, University of Cyprus, 1 University Avenue, University Campus, 2109 Nicosia, Cyprus
| | - Abderrezak Belabbes
- Center
for Catalysis and Separations, Khalifa University
of Science and Technology, Main Campus, Abu Dhabi 127788, UAE
| | - Lourdes F. Vega
- Center
for Catalysis and Separations, Khalifa University
of Science and Technology, Main Campus, Abu Dhabi 127788, UAE
- Research
and Innovation Center on CO2 and H2 (RICH),
and Chemical Engineering Department, Khalifa
University, Abu Dhabi 127788, UAE
| | - Abdallah Fathy Zedan
- National
Institute of Laser Enhanced Science, Cairo
University, Giza 12613, Egypt
| | - Steven J. Hinder
- The
Surface Analysis Laboratory, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 4DL, U.K.
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18
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Park JH, Jung CH, Kim KJ, Kim D, Shin HR, Hong JE, Lee KT. Enhancing Bifunctional Electrocatalytic Activities of Oxygen Electrodes via Incorporating Highly Conductive Sm 3+ and Nd 3+ Double-Doped Ceria for Reversible Solid Oxide Cells. ACS Appl Mater Interfaces 2021; 13:2496-2506. [PMID: 33398987 DOI: 10.1021/acsami.0c17238] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Solid oxide cells (SOCs) are mutually convertible energy devices capable of generating electricity from chemical fuels including hydrogen in the fuel cell mode and producing green hydrogen using electricity from renewable but intermittent solar and wind resources in the electrolysis cell mode. An effective approach to enhance the performance of SOCs at reduced temperatures is by developing highly active oxygen electrodes for both oxygen reduction and oxygen evolution reactions. Herein, highly conductive Sm3+ and Nd3+ double-doped ceria (Sm0.075Nd0.075Ce0.85O2-δ, SNDC) is utilized as an active component for reversible SOC applications. We develop a novel La0.6Sr0.4Co0.2Fe0.8O3 -δ (LSCF)-SNDC composite oxygen electrode. Compared with the conventional LSCF-Gd-doped ceria oxygen electrode, the LSCF-SNDC exhibits ∼35% lower cathode polarization resistance (0.042 Ω cm2 at 750 °C) owing to rapid oxygen incorporation and surface diffusion kinetics. Furthermore, the SOC with the LSCF-SNDC oxygen electrode and the SNDC buffer layer yields a remarkable performance in both the fuel cell (1.54 W cm-2 at 750 °C) and electrolysis cell (1.37 A cm-2 at 750 °C) modes because the incorporation of SNDC promotes the surface diffusion kinetics at the oxygen electrode bulk and the activity of the triple phase boundary at the interface. These findings suggest that the highly conductive SNDC material effectively enhances both oxygen reduction and oxygen evolution reactions, thus serving as a promising material in reversible SOC applications at reduced temperatures.
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Affiliation(s)
- Jeong Hwa Park
- Department of Energy Science and Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Republic of Korea
| | - Chan Hoon Jung
- Department of Energy Science and Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Republic of Korea
| | - Kyeong Joon Kim
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Doyeub Kim
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Hong Rim Shin
- Department of Energy Science and Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Republic of Korea
| | - Jong-Eun Hong
- Fuel Cell Laboratory, Korea Institute of Energy Research, Daejeon 34129, Republic of Korea
| | - Kang Taek Lee
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
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19
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Sediva E, Bohdanov D, Harrington GF, Rafalovskyi I, Drahokoupil J, Borodavka F, Marton P, Hlinka J. Anisotropic Strain in Rare-Earth Substituted Ceria Thin Films Probed by Polarized Raman Spectroscopy and First-Principles Calculations. ACS Appl Mater Interfaces 2020; 12:56251-56259. [PMID: 33270441 DOI: 10.1021/acsami.0c14249] [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] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Lattice strain in oxygen ion conductors can be used to tune their functional properties for applications in fuel cells, sensors, or catalysis. However, experimental measurements of thin film strain in both in- and out-of-plane directions can be experimentally challenging. We propose a method for measuring strain in rare-earth doped ceria thin films by polarized Raman spectroscopy. We study epitaxial CeO2 films substituted by La, Gd, and Yb grown on MgO substrates with BaZrO3 and SrTiO3 interlayers, where different levels of strain are generated by annealing at distinct temperatures. The films show in-plane compression and out-of-plane expansion, resulting in a lowering from the bulk cubic to tetragonal lattice symmetry. This leads to the splitting of the F2g Raman mode in the cubic phase to B2g and Eg modes in the tetragonal lattice. The symmetry and frequency of these modes are determined by polarized Raman in the backscattering and right-angle scattering geometries as well as by first-principal calculations. The frequency splitting of the two modes is proportional to the strain measured by X-ray diffraction and its magnitude agrees with first-principles calculations. The results offer a fast, nondestructive, and precise method for measuring both in- and out-of-plane strain in ceria and can be readily applied to other ionic conductors.
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Affiliation(s)
- Eva Sediva
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 1999/2, Prague 18221, Czech Republic
| | - Dmytro Bohdanov
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 1999/2, Prague 18221, Czech Republic
| | - George F Harrington
- Center of Coevolutionary Research for Sustainable Communities (C2RSC), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Iegor Rafalovskyi
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 1999/2, Prague 18221, Czech Republic
| | - Jan Drahokoupil
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 1999/2, Prague 18221, Czech Republic
| | - Fedir Borodavka
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 1999/2, Prague 18221, Czech Republic
| | - Pavel Marton
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 1999/2, Prague 18221, Czech Republic
| | - Jiri Hlinka
- Institute of Physics of the Czech Academy of Sciences, Na Slovance 1999/2, Prague 18221, Czech Republic
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20
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Zhang H, Castelli IE, Santucci S, Sanna S, Pryds N, Esposito V. Atomic-scale insights into electro-steric substitutional chemistry of cerium oxide. Phys Chem Chem Phys 2020; 22:21900-21908. [PMID: 32969460 DOI: 10.1039/d0cp03298k] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Cerium oxide (ceria, CeO2) is one of the most promising mixed ionic and electronic conducting materials. Previous atomistic analysis has widely covered the effects of substitution on oxygen vacancy migration. However, an in-depth analysis of the role of cation substitution beyond trivalent cations has rarely been explored. Here, we investigate soluble monovalent (Li+, Na+, K+, Rb+), divalent (Fe2+, Co2+, Mn2+, Mg2+, Ni2+, Zn2+, Cd2+, Ca2+, Sr2+, Ba2+), trivalent (Al3+, Fe3+, Sc3+, In3+, Lu3+, Yb3+, Y3+, Er3+, Gd3+, Eu3+, Nd3+, Pr3+, La3+) and tetravalent (Si4+, Ge4+, Ti4+, Sn4+, Hf4+, Zr4+) cation substituents. By combining classical simulations and quantum mechanical calculations, we provide an insight into defect association energies between substituent cations and oxygen vacancies as well as their effects on the diffusion mechanisms. Our simulations indicate that oxygen ionic diffusivity of subvalent cation-substituted systems follows the order Gd3+ > Ca2+ > Na+. With the same charge, a larger size mismatch with the Ce4+ cation yields a lower oxygen ionic diffusivity, i.e., Na+ > K+, Ca2+ > Ni2+, Gd3+ > Al3+. Based on these trends, we identify species that could tune the oxygen ionic diffusivity: we estimate that the optimum oxygen vacancy concentration for achieving fast oxygen ionic transport is ≈2.5% for GdxCe1-xO2-x/2, CaxCe1-xO2-x and NaxCe1-xO2-3x/2 at 800 K. Remarkably, such a concentration is not constant and shifts gradually to higher values as the temperature is increased. We find that co-substitutions can enhance the impact of the single substitutions beyond that expected by their simple addition. Furthermore, we identify preferential oxygen ion migration pathways, which illustrate the electro-steric effects of substituent cations in determining the energy barrier of oxygen ion migration. Such fundamental insights into the factors that govern the oxygen diffusion coefficient and migration energy would enable design criteria to be defined for tuning the ionic properties of the material, e.g., by co-substitutions.
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Affiliation(s)
- Haiwu Zhang
- Department of Energy Conversion and Storage, Technical University of Denmark, Anker Engelunds Vej 411, DK-2800 Kgs. Lyngby, Denmark.
| | - Ivano E Castelli
- Department of Energy Conversion and Storage, Technical University of Denmark, Anker Engelunds Vej 411, DK-2800 Kgs. Lyngby, Denmark.
| | - Simone Santucci
- Department of Energy Conversion and Storage, Technical University of Denmark, Anker Engelunds Vej 411, DK-2800 Kgs. Lyngby, Denmark.
| | - Simone Sanna
- Department of Energy Conversion and Storage, Technical University of Denmark, Anker Engelunds Vej 411, DK-2800 Kgs. Lyngby, Denmark.
| | - Nini Pryds
- Department of Energy Conversion and Storage, Technical University of Denmark, Anker Engelunds Vej 411, DK-2800 Kgs. Lyngby, Denmark.
| | - Vincenzo Esposito
- Department of Energy Conversion and Storage, Technical University of Denmark, Anker Engelunds Vej 411, DK-2800 Kgs. Lyngby, Denmark.
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21
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Genreith‐Schriever AR, Parras JP, Heelweg HJ, De Souza RA. The Intrinsic Structural Resistance of a Grain Boundary to Transverse Ionic Conduction. ChemElectroChem 2020. [DOI: 10.1002/celc.202000773] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
| | - Jana P. Parras
- Institute of Physical Chemistry RWTH Aachen University Landoltweg 2 52056 Aachen Germany
| | - Henrik J. Heelweg
- Institute of Physical Chemistry RWTH Aachen University Landoltweg 2 52056 Aachen Germany
| | - Roger A. De Souza
- Institute of Physical Chemistry RWTH Aachen University Landoltweg 2 52056 Aachen Germany
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22
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Chemura S, Haubitz T, Primus PA, Underberg M, Hülser T, Kumke MU. Europium-Doped Ceria-Gadolinium Mixed Oxides: PARAFAC Analysis and High-Resolution Emission Spectroscopy under Cryogenic Conditions for Structural Analysis. J Phys Chem A 2020; 124:4972-4983. [PMID: 32450696 DOI: 10.1021/acs.jpca.0c03188] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Gadolinium-doped ceria or gadolinium-stabilized ceria (GDC) is an important technical material due to its ability to conduct O2- ions, e.g., used in solid oxide fuel cells operated at intermediate temperature as an electrolyte, diffusion barrier, and electrode component. We have synthesized Ce1-xGdxO2-y:Eu3+ (0 ≤ x ≤ 0.4) nanoparticles (11-15 nm) using a scalable spray pyrolysis method, which allows the continuous large-scale technical production of such materials. Introducing Eu3+ ions in small amounts into ceria and GDC as spectroscopic probes can provide detailed information about the atomic structure and local environments and allows us to monitor small structural changes. This study presents a novel approach to structurally elucidate europium-doped Ce1-xGdxO2-y:Eu3+ nanoparticles by way of Eu3+ spectroscopy, processing the spectroscopic data with the multiway decomposition method parallel factor (PARAFAC) analysis. In order to perform the deconvolution of spectra, data sets of excitation wavelength, emission wavelength, and time are required. Room temperature, time-resolved emission spectra recorded at λex = 464 nm show that Gd3+ doping results in significantly altered emission spectra compared to pure ceria. The PARAFAC analysis for the pure ceria samples reveals a high-symmetry species (which can also be probed directly via the CeO2 charge transfer band) and a low-symmetry species. The GDC samples yield two low-symmetry spectra in the same experiment. High-resolution emission spectra recorded under cryogenic conditions after probing the 5D0-7F0 transition at λex = 575-583 nm revealed additional variation in the low-symmetry Eu3+ sites in pure ceria and GDC. The total luminescence spectra of CeO2-y:Eu3+ showed Eu3+ ions located in at least three slightly different coordination environments with the same fundamental symmetry, whereas the overall hypsochromic shift and increased broadening of the 5D0-7F0 excitation in the GDC samples, as well as the broadened spectra after deconvolution point to less homogeneous environments. The data of the Gd3+-containing samples indicates that the average charge density around the Eu3+ ions in the lattice is decreased with increasing Gd3+ and oxygen vacancy concentration. For reference, the Judd-Ofelt parameters of all spectra were calculated. PARAFAC proves to be a powerful tool to analyze lanthanide spectra in crystalline solid materials, which are characterized by numerous Stark transitions and where measurements usually yield a superposition of different contributions to any given spectrum.
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Affiliation(s)
- Sitshengisiwe Chemura
- Institute of Chemistry (Physical Chemistry), University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
| | - Toni Haubitz
- Institute of Chemistry (Physical Chemistry), University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
| | - Philipp A Primus
- Institute of Chemistry (Physical Chemistry), University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
| | - Martin Underberg
- Institut für Energie- und Umwelttechnik e.V. (IUTA), Bliersheimer Str. 58-60, 47229 Duisburg, Germany
| | - Tim Hülser
- Institut für Energie- und Umwelttechnik e.V. (IUTA), Bliersheimer Str. 58-60, 47229 Duisburg, Germany
| | - Michael U Kumke
- Institute of Chemistry (Physical Chemistry), University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
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23
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Abstract
The oxygen ion conductivity of polycrystalline samples of Lu doped ceria is studied using impedance spectroscopy. Lutetium doped ceria is of particular interest as Lu has a similar ionic radius as the host cation Ce. The change of the ionic conductivity as a function of the Lu dopant fraction is investigated in detail revealing a similar behavior as Sm doped ceria that has one of the highest ionic conductivity in ternary cerium oxides. In comparison with simulations, the experimental dependence of the conductivity on the dopant fraction reveals that migration barriers for oxygen vacancy jumps around Lu ions are slightly higher than for jumps in pure ceria. The absolute conductivity is small due to the strong trapping of oxygen vacancies near Lu dopants.
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Affiliation(s)
- Julius Koettgen
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany. JARA-HPC, Forschungszentrum Jülich and RWTH Aachen University, Germany. Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States of America. Department of Materials Science and Engineering, University of California, Berkeley, California 94720, United States of America
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24
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Abstract
CeO2-based materials have been studied intensively as anodes for intermediate temperature solid oxide fuel cells (IT-SOFCs). In this work, pristine and europium (Eu)-doped CeO2 nanowires were comprehensively investigated as anode materials for IT-SOFCs, by a combination of theoretical predictions and experimental characterizations. The results demonstrate: (1) Oxygen vacancies can be energetically favorably introduced into the CeO2 lattice by Eu doping; (2) The lattice parameter of the ceria increases linearly with the Eu content when it varies from 0 to 35 mol.%, simultaneously resulting in a significant increase in oxygen vacancies. The concentration of oxygen vacancies reaches its maximum at a ca. 10 mol.% Eu doping level and decreases thereafter; (3) The highest oxygen ion conductivity is achieved at a Eu content of 15 mol.%; while the 10 mol.% Eu-doped CeO2 sample displays the highest catalytic activity for H2-TPR and CO oxidization reactions. The conducting and catalytic properties benefit from the expanded lattice, the large amount of oxygen vacancies, the enhanced reactivity of surface oxygen and the promoted mobility of bulk oxygen ions. These results provide an avenue toward designing and optimizing CeO2 as a promising anode for SOFCs.
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Affiliation(s)
- Shuai Li
- Department of Physics, Academy for Advanced Interdisciplinary Studies, Southern University of Science and Technology, Shenzhen, China.,Shenzhen Key Laboratory of Solid State Batteries, Guangdong Provincial Key Laboratory of Energy Materials for Electric Power, Southern University of Science and Technology, Shenzhen, China.,Key Laboratory for Renewable Energy, Beijing Key Laboratory for New Energy Materials and Devices, Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - Xia Lu
- School of Materials, Sun Yat-sen University, Guangzhou, China
| | - Siqi Shi
- School of Materials Science and Engineering, Shanghai University, Shanghai, China
| | - Liquan Chen
- Key Laboratory for Renewable Energy, Beijing Key Laboratory for New Energy Materials and Devices, Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - Zhaoxiang Wang
- Key Laboratory for Renewable Energy, Beijing Key Laboratory for New Energy Materials and Devices, Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - Yusheng Zhao
- Department of Physics, Academy for Advanced Interdisciplinary Studies, Southern University of Science and Technology, Shenzhen, China.,Shenzhen Key Laboratory of Solid State Batteries, Guangdong Provincial Key Laboratory of Energy Materials for Electric Power, Southern University of Science and Technology, Shenzhen, China
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Han X, Amrane N, Zhang Z, Benkraouda M. Interplay between Gd and oxygen vacancy on the electronic properties and defect chemistry of Gd-doped CeO2: A DFT + U study. Chem Phys 2020; 534:110741. [DOI: 10.1016/j.chemphys.2020.110741] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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26
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Bezrkovnyi O, Vorokhta M, Małecka M, Mista W, Kepinski L. NAP-XPS study of Eu3+ → Eu2+ and Ce4+ → Ce3+ reduction in Au/Ce0.80Eu0.20O2 catalyst. CATAL COMMUN 2020. [DOI: 10.1016/j.catcom.2019.105875] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Murakami K, Ogo S, Ishikawa A, Takeno Y, Higo T, Tsuneki H, Nakai H, Sekine Y. Heteroatom doping effects on interaction of H 2O and CeO 2 (111) surfaces studied using density functional theory: Key roles of ionic radius and dispersion. J Chem Phys 2020; 152:014707. [PMID: 31914759 DOI: 10.1063/1.5138670] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Understanding heteroatom doping effects on the interaction between H2O and cerium oxide (ceria, CeO2) surfaces is crucially important for elucidating heterogeneous catalytic reactions of CeO2-based oxides. Surfaces of CeO2 (111) doped with quadrivalent (Ti, Zr), trivalent (Al, Ga, Sc, Y, La), or divalent (Ca, Sr, Ba) cations are investigated using density functional theory (DFT) calculations modified for onsite Coulomb interactions (DFT + U). Trivalent (except for Al) and divalent cation doping induces the formation of intrinsic oxygen vacancy (Ovac), which is backfilled easily by H2O. Partially OH-terminated surfaces are formed. Furthermore, dissociative adsorption of H2O is simulated on the OH terminated surfaces (for trivalent or divalent cation doped models) and pure surfaces (for Al and quadrivalent cation doped surfaces). The ionic radius is crucially important. In fact, H2O dissociates spontaneously on the small cations. Although a slight change is induced by doping as for the H2O adsorption energy at Ce sites, the H2O dissociative adsorption at Ce sites is well-assisted by dopants with a smaller ionic radius. In terms of the amount of promoted Ce sites, the arrangement of dopant sites is also fundamentally important.
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Affiliation(s)
- Kota Murakami
- Applied Chemistry, Waseda University, 3-4-1, Okubo, Shinjuku, Tokyo 169-8555, Japan
| | - Shuhei Ogo
- Applied Chemistry, Waseda University, 3-4-1, Okubo, Shinjuku, Tokyo 169-8555, Japan
| | - Atsushi Ishikawa
- PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Yuna Takeno
- Applied Chemistry, Waseda University, 3-4-1, Okubo, Shinjuku, Tokyo 169-8555, Japan
| | - Takuma Higo
- Applied Chemistry, Waseda University, 3-4-1, Okubo, Shinjuku, Tokyo 169-8555, Japan
| | - Hideaki Tsuneki
- Applied Chemistry, Waseda University, 3-4-1, Okubo, Shinjuku, Tokyo 169-8555, Japan
| | - Hiromi Nakai
- Chemistry and Biochemistry, Waseda University, 3-4-1, Okubo, Shinjuku, Tokyo 169-8555, Japan
| | - Yasushi Sekine
- Applied Chemistry, Waseda University, 3-4-1, Okubo, Shinjuku, Tokyo 169-8555, Japan
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28
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Bowman WJ, Darbal A, Crozier PA. Linking Macroscopic and Nanoscopic Ionic Conductivity: A Semiempirical Framework for Characterizing Grain Boundary Conductivity in Polycrystalline Ceramics. ACS Appl Mater Interfaces 2020; 12:507-517. [PMID: 31800213 DOI: 10.1021/acsami.9b15933] [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: 06/10/2023]
Abstract
Understanding the chemical and charge transport properties of grain boundaries (GBs) with high point defect concentrations (beyond the dilute solution limit) in polycrystalline materials is critical for developing ion-conducting solids for electrochemical energy conversion and storage. Elucidation and optimization of GBs are hindered by large variations in atomic structure, composition, and chemistry within nanometers or Ångstroms of the GB interface, which limits a fundamental understanding of electrical transport across and along GBs. Here we employ a novel correlated approach that is generally applicable to polycrystalline materials whose properties are affected by GB composition or chemistry. We demonstrate the connection between the nanoscopic chemical and transport properties of individual boundaries and the macroscopic ionic conductivity in oxygen-conducting Pr0.04Gd0.11Ce0.85O2-δ. The key finding is that GBs with higher solute concentration have lower activation energy for cross-GB ion conduction through a polycrystalline conductor. The resultant semiempirical framework presented here provides a tool for understanding, designing and optimizing polycrystalline ionic conductors.
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Affiliation(s)
- William J Bowman
- School for Engineering of Matter, Transport and Energy , Arizona State University , 501 E. Tyler Mall , Tempe , Arizona 85287-6106 , United States
| | - Amith Darbal
- Nanomegas USA , 1095 W. Rio Salado Pkwy #110 , Tempe , Arizona 85281 , United States
| | - Peter A Crozier
- School for Engineering of Matter, Transport and Energy , Arizona State University , 501 E. Tyler Mall , Tempe , Arizona 85287-6106 , United States
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29
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Schmitt R, Nenning A, Kraynis O, Korobko R, Frenkel AI, Lubomirsky I, Haile SM, Rupp JLM. A review of defect structure and chemistry in ceria and its solid solutions. Chem Soc Rev 2019; 49:554-592. [PMID: 31872840 DOI: 10.1039/c9cs00588a] [Citation(s) in RCA: 114] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Ceria and its solid solutions play a vital role in several industrial processes and devices. These include solar energy-to-fuel conversion, solid oxide fuel and electrolyzer cells, memristors, chemical looping combustion, automotive 3-way catalysts, catalytic surface coatings, supercapacitors and recently, electrostrictive devices. An attractive feature of ceria is the possibility of tuning defect-chemistry to increase the effectiveness of the materials in application areas. Years of study have revealed many features of the long-range, macroscopic characteristics of ceria and its derivatives. In this review we focus on an area of ceria defect chemistry which has received comparatively little attention - defect-induced local distortions and short-range associates. These features are non-periodic in nature and hence not readily detected by conventional X-ray powder diffraction. We compile the relevant literature data obtained by thermodynamic analysis, Raman spectroscopy, and X-ray absorption fine structure (XAFS) spectroscopy. Each of these techniques provides insight into material behavior without reliance on long-range periodic symmetry. From thermodynamic analyses, association of defects is inferred. From XAFS, an element-specific probe, local structure around selected atomic species is obtained, whereas from Raman spectroscopy, local symmetry breaking and vibrational changes in bonding patterns is detected. We note that, for undoped ceria and its solid solutions, the relationship between short range order and cation-oxygen-vacancy coordination remains a subject of active debate. Beyond collating the sometimes contradictory data in the literature, we strengthen this review by reporting new spectroscopy results and analysis. We contribute to this debate by introducing additional data and analysis, with the expectation that increasing our fundamental understanding of this relationship will lead to an ability to predict and tailor the defect-chemistry of ceria-based materials for practical applications.
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Affiliation(s)
- Rafael Schmitt
- Electrochemical Materials, Department of Materials, ETH Zurich, Switzerland
| | - Andreas Nenning
- Electrochemical Materials, Department of Materials, ETH Zurich, Switzerland and Electrochemical Materials, Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. and TU Wien, Institute of Chemical Technologies and Analytics, Vienna, 1060, Austria
| | - Olga Kraynis
- Department Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Roman Korobko
- Electrochemical Materials, Department of Materials, ETH Zurich, Switzerland and Department Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Anatoly I Frenkel
- Department of Materials Science and Chemical Engineering, Stony Brook University, Stony Brook, NY 11794, USA
| | - Igor Lubomirsky
- Department Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Sossina M Haile
- Materials Science and Engineering, Northwestern University, Evanston, IL, USA
| | - Jennifer L M Rupp
- Electrochemical Materials, Department of Materials, ETH Zurich, Switzerland and Electrochemical Materials, Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. and Electrochemical Materials, Department of Electrical Engineering & Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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30
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Rehman S, Kim H, Farooq Khan M, Hur JH, Lee AD, Kim DK. Tuning of ionic mobility to improve the resistive switching behavior of Zn-doped CeO 2. Sci Rep 2019; 9:19387. [PMID: 31852939 PMCID: PMC6920484 DOI: 10.1038/s41598-019-55716-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [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: 07/25/2019] [Accepted: 12/02/2019] [Indexed: 11/08/2022] Open
Abstract
Correlation between the resistive switching characteristics of Au/Zn-doped CeO2/Au devices and ionic mobility of CeO2 altered by the dopant concentration were explored. It was found that the ionic mobility of CeO2 has a profound effect on the operating voltages of the devices. The magnitude of operating voltage was observed to decrease when the doping concentration of Zn was increased up to 14%. After further increasing the doping level to 24%, the device hardly exhibits any resistive switching. At a low doping concentration, only isolated Vo existed in the CeO2 lattice. At an intermediate doping concentration, the association between dopant and Vo formed (Zn, Vo)× defect clusters. Low number density of these defect clusters initially favored the formation of Vo filament and led to a reduction in operating voltage. As the size and number density of (Zn, Vo)× defect clusters increased at a higher doping concentration, the ionic conductivity was limited with the trapping of isolated Vo by these defect clusters, which resulted in the diminishing of resistive switching. This research work provides a strategy for tuning the mobility of Vo to modulate resistive switching characteristics for non-volatile memory applications.
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Affiliation(s)
- Shania Rehman
- Department of Electrical Engineering, Sejong University, Seoul, 05006, Republic of Korea
| | - Honggyun Kim
- Department of Electrical Engineering, Sejong University, Seoul, 05006, Republic of Korea
| | - Muhammad Farooq Khan
- Department of Electrical Engineering, Sejong University, Seoul, 05006, Republic of Korea
| | - Ji-Hyun Hur
- Department of Electrical Engineering, Sejong University, Seoul, 05006, Republic of Korea
| | - Anthony D Lee
- Department of Mechanical Engineering Technology, Farmingdale State College, Farmingdale, New York, 11735, USA
| | - Deok-Kee Kim
- Department of Electrical Engineering, Sejong University, Seoul, 05006, Republic of Korea.
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31
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He L, Meng J, Feng J, Yao F, Zhang L, Zhang Z, Liu X, Zhang H. Investigation of 4f-Related Electronic Transitions of Rare-Earth Doped ZnO Luminescent Materials: Insights from First-Principles Calculations. Chemphyschem 2019; 21:51-58. [PMID: 31696633 DOI: 10.1002/cphc.201900981] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [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: 10/09/2019] [Revised: 10/31/2019] [Indexed: 01/10/2023]
Abstract
Rare-earth (RE) doped zinc oxides (ZnO) are regarded as promising materials for application in versatile color-tuned devices. However, the understanding of underlying luminescence mechanism and the rule of 4 f-related electronic transition is still limited, which is full of significance for the exploration of advanced RE-based ZnO phosphors. Thus, a series of ZnO : RE (RE=Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb) phosphors have been investigated by means of first-principles calculations. Meanwhile, we also consider the effect of native defects (VO , VZn ) on the luminescence of ZnO : RE phosphors. Accordingly, four types of electric-dipole allowed transition processes are figured out in ZnO : RE family. Additionally, we manifest that the VO can further improve the luminescent performance of ZnO : RE phosphors, and give insightful guidance to design desired RE-based ZnO materials with excellent luminescence.
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Affiliation(s)
- Lingjun He
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China
| | - Junling Meng
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China
| | - Jing Feng
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China
| | - Fen Yao
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China
| | - Lifang Zhang
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China
| | - Zhixiang Zhang
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China
| | - Xiaojuan Liu
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China
| | - Hongjie Zhang
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China
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Dholabhai PP. Atomic-scale structure of misfit dislocations in CeO 2/MgO heterostructures and thermodynamic stability of dopant-defect complexes at the heterointerface. Phys Chem Chem Phys 2019; 21:20878-20891. [PMID: 31517361 DOI: 10.1039/c9cp03727f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Complex oxide heterostructures and thin films have found applications across the board in some of the most advanced technologies, wherein the interfaces between the two mismatched oxides influence novel functionalities. It is imperative to comprehend the atomic-scale structure of misfit dislocations, which are ubiquitous in semi-coherent oxide heterostructures, and obtain a fundamental understanding of their interaction with point defects and dopants to predict and control their interface-governed properties. Here, we report atomistic simulations elucidating the atomic-scale structure of misfit dislocations in CeO2/MgO heterostructures. Our results demonstrate that the 45° rotation of CeO2 thin film is one of the potential fundamental mechanisms responsible for eliminating the surface dipole, leading to the experimentally observed mixed epitaxial relationship. We further report the thermodynamic stability of diverse dopant-defect complexes near misfit dislocations, wherein various scenarios for nearest neighbor bonding environments within the complexes are explored. Complex misfit dislocation structure, asymmetry, strain, and the availability of diverse nearest neighbor bonding environments between dopants and oxygen defects at the interface are accountable for a wide dispersion in energies within a given dopant-defect arrangement. As opposed to the bulk, the thermodynamic stability of oxygen vacancies is found to be sensitive to the dopant arrangement at the heterointerface. Extended stabilities of dopant-defect complexes at misfit dislocations reveal that they would influence ionic transport at heterointerfaces of fluorite-structured thin film electrolytes. Notably, the results herein offer a fundamental atomic-scale perspective of the intricate interplay between dopants, defects, and misfit dislocations at the heterointerfaces in mismatched oxide heterostructures.
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Affiliation(s)
- Pratik P Dholabhai
- School of Physics and Astronomy, Rochester Institute of Technology, Rochester, NY 14623, USA.
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33
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Coduri M, Bozzetti D, Checchia S, Brunelli M, Scavini M. Local and Average Structure of Yb-Doped Ceria through Synchrotron and Neutron Pair Distribution Function. Inorganics 2019; 7:102. [DOI: 10.3390/inorganics7080102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
As transport properties of doped ceria electrolytes depend significantly on the nature of the dopant and the defectivity, the design of new materials and devices requires proper understanding of the defect structure. Among lanthanide dopants, Yb shows some peculiar characteristics that call for a possible different defect structure compared to Gd and Sm conventional dopants, which could be linked to its poorer performance. For this purpose, we combine synchrotron and neutron powder diffraction exploiting the Rietveld and Pair distribution Function. By increasing its concentration, Yb produces qualitatively the same structural distortions as other dopants, leading to a domain structure involving the progressive nucleation and growth of nanodomains with a Yb2O3-like (C-type) structure hosted in a fluorite CeO2 matrix. However, when it comes to growing the C-type nanodomains into a long-range phase, the transformation is less pronounced. At the same time, a stronger structural distortion occurs at the local scale, which is consistent with the segregation of a large amount of oxygen vacancies. The strong trapping of VOs by Yb3+ explains the poor performance of Yb-doped ceria with respect to conventional Sm-, Gd-, and Y-doped samples at equal temperature and dopant amount.
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Kettner M, Duchoň T, Wolf MJ, Kullgren J, Senanayake SD, Hermansson K, Veltruská K, Nehasil V. Anion-mediated electronic effects in reducible oxides: Tuning the valence band of ceria via fluorine doping. J Chem Phys 2019; 151:044701. [PMID: 31370552 DOI: 10.1063/1.5109955] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Combining experimental spectroscopy and hybrid density functional theory calculations, we show that the incorporation of fluoride ions into a prototypical reducible oxide surface, namely, ceria(111), can induce a variety of nontrivial changes to the local electronic structure, beyond the expected increase in the number of Ce3+ ions. Our resonant photoemission spectroscopy results reveal new states above, within, and below the valence band, which are unique to the presence of fluoride ions at the surface. With the help of hybrid density functional calculations, we show that the different states arise from fluoride ions in different atomic layers in the near surface region. In particular, we identify a structure in which a fluoride ion substitutes for an oxygen ion at the surface, with a second fluoride ion on top of a surface Ce4+ ion giving rise to F 2p states which overlap the top of the O 2p band. The nature of this adsorbate F--Ce4+ resonant enhancement feature suggests that this bond is at least partially covalent. Our results demonstrate the versatility of anion doping as a potential means of tuning the valence band electronic structure of ceria.
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Affiliation(s)
- Miroslav Kettner
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000 Prague 8, Czech Republic
| | - Tomáš Duchoň
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000 Prague 8, Czech Republic
| | - Matthew J Wolf
- Department of Chemistry-Ångström Laboratory, Uppsala University, Box 538, 751 21 Uppsala, Sweden
| | - Jolla Kullgren
- Department of Chemistry-Ångström Laboratory, Uppsala University, Box 538, 751 21 Uppsala, Sweden
| | - Sanjaya D Senanayake
- Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Kersti Hermansson
- Department of Chemistry-Ångström Laboratory, Uppsala University, Box 538, 751 21 Uppsala, Sweden
| | - Kateřina Veltruská
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000 Prague 8, Czech Republic
| | - Václav Nehasil
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000 Prague 8, Czech Republic
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35
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Han ZK, Zhang L, Liu M, Ganduglia-Pirovano MV, Gao Y. The Structure of Oxygen Vacancies in the Near-Surface of Reduced CeO 2 (111) Under Strain. Front Chem 2019; 7:436. [PMID: 31275923 PMCID: PMC6592146 DOI: 10.3389/fchem.2019.00436] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [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: 03/03/2019] [Accepted: 05/28/2019] [Indexed: 11/17/2022] Open
Abstract
Strain has been widely recognized as important for tuning the behavior of defects in metal oxides since properties such as defect configuration, electronic structure, excess charge localization, and local atomic distortions may be affected by surface strain. In CeO2, the most widely used promoter in three-way catalysts and solid state electrolyte in fuel cells, the behaviors of oxygen vacancies, and associated Ce3+ polarons are crucial in applications. Recent STM and AFM investigations as well as DFT-based calculations have indicated that in the near-surface of CeO2 (111), at low temperatures and vacancy concentrations, subsurface oxygen vacancies are more stable than surface ones, and the Ce3+ ions are next-nearest neighbors to both types of vacancies, which can be explained by the better ability of the system to relax the lattice strain induced by vacancy formation as well as by the excess charge localization. The results also revealed that the interaction between first-neighbor vacancies is repulsive. In this work, the relative stability of surface and subsurface oxygen vacancies at the CeO2 (111) surface under in-plane strain is investigated by means of DFT+U calculations. The tensile strain favors isolated surface vacancies with next nearest neighbor polarons, whereas isolated subsurface vacancies with nearest neighbor polarons are energetically favored under compressive strain. In addition, the formation of both surface and subsurface dimers is favored over having corresponding isolated species under compressive strain, which implies the possibility of controlling the formation of vacancy clusters using strain. In many applications, ceria is employed as a supported thin film or within a heterostructure in which ceria can be strained, and this study shows that strain can be a useful handle to tune properties of such materials.
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Affiliation(s)
- Zhong-Kang Han
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, China
| | - Lei Zhang
- Center for Innovative Fuel Cell and Battery Technologies, School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA, United States
| | - Meilin Liu
- Center for Innovative Fuel Cell and Battery Technologies, School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA, United States
| | | | - Yi Gao
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, China.,Zhangjiang Laboratory, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, China
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Affiliation(s)
- Phanikumar Pentyala
- Quantum and Molecular Engineering Laboratory, Department of Chemical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Parag A. Deshpande
- Quantum and Molecular Engineering Laboratory, Department of Chemical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
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Lee J, Ohba N, Asahi R. First-principles prediction of high oxygen-ion conductivity in trilanthanide gallates Ln 3GaO 6. Sci Technol Adv Mater 2019; 20:144-159. [PMID: 30863467 PMCID: PMC6407603 DOI: 10.1080/14686996.2019.1578183] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 01/31/2019] [Accepted: 01/31/2019] [Indexed: 06/09/2023]
Abstract
We systematically investigated trilanthanide gallates (Ln3GaO6) with the space group Cmc21 as oxygen-ion conductors using first-principles calculations. Six Ln3GaO6 (Ln = Nd, Gd, Tb, Ho, Dy, or Er) are both energetically and dynamically stable among 15 Ln3GaO6 compounds, which is consistent with previous experimental studies reporting successful syntheses of single phases. La3GaO6 and Lu3GaO6 may be metastable despite a slightly higher energy than those of competing reference states, as phonon calculations predict them to be dynamically stable. The formation and the migration barrier energies of an oxygen vacancy (V O) suggest that eight Ln3GaO6 (Ln = La, Nd, Gd, Tb, Ho, Dy, Er, or Lu) can act as oxygen-ion conductors based on V O. Ga plays a role of decreasing the distances between the oxygen sites of Ln3GaO6 compared with those of Ln2O3 so that a V O migrates easier with a reduced migration barrier energy. Larger oxygen-ion diffusivities and lower migration barrier energies of V O for the eight Ln3GaO6 are obtained for smaller atomic numbers of Ln having larger radii of Ln3+. Their oxygen-ion conductivities at 1000 K are predicted to have a similar order of magnitude to that of yttria-stabilized zirconia.
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Affiliation(s)
- Joohwi Lee
- Toyota Central R&D Laboratories, Inc., Nagakute, Japan
| | - Nobuko Ohba
- Toyota Central R&D Laboratories, Inc., Nagakute, Japan
| | - Ryoji Asahi
- Toyota Central R&D Laboratories, Inc., Nagakute, Japan
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Coduri M, Checchia S, Longhi M, Ceresoli D, Scavini M. Rare Earth Doped Ceria: The Complex Connection Between Structure and Properties. Front Chem 2018; 6:526. [PMID: 30430105 PMCID: PMC6220118 DOI: 10.3389/fchem.2018.00526] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [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: 08/16/2018] [Accepted: 10/11/2018] [Indexed: 11/19/2022] Open
Abstract
The need for high efficiency energy production, conversion, storage and transport is serving as a robust guide for the development of new materials. Materials with physical-chemical properties matching specific functions in devices are produced by suitably tuning the crystallographic- defect- and micro-structure of the involved phases. In this review, we discuss the case of Rare Earth doped Ceria. Due to their high oxygen diffusion coefficient at temperatures higher than ~500°C, they are very promising materials for several applications such as electrolytes for Solid Oxide Fuel and Electrolytic Cells (SOFC and SOEC, respectively). Defects are integral part of the conduction process, hence of the final application. As the fluorite structure of ceria is capable of accommodating a high concentration of lattice defects, the characterization and comprehension of such complex and highly defective materials involve expertise spanning from computational chemistry, physical chemistry, catalysis, electrochemistry, microscopy, spectroscopy, and crystallography. Results coming from different experimental and computational techniques will be reviewed, showing that structure determination (at different scale length) plays a pivotal role bridging theoretical calculation and physical properties of these complex materials.
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Affiliation(s)
- Mauro Coduri
- ESRF - The European Synchrotron, Grenoble, France
| | | | - Mariangela Longhi
- Dipartimento di Chimica, Università degli Studi di Milano, Milan, Italy
| | - Davide Ceresoli
- Istituto di Scienze e Tecnologie Molecolari, CNR, Milan, Italy
| | - Marco Scavini
- Dipartimento di Chimica, Università degli Studi di Milano, Milan, Italy
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Zhang L, Meng J, Yao F, Zhang W, Liu X, Meng J, Zhang H. Insight into the Mechanism of the Ionic Conductivity for Ln-Doped Ceria (Ln = La, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, and Tm) through First-Principles Calculation. Inorg Chem 2018; 57:12690-12696. [DOI: 10.1021/acs.inorgchem.8b01853] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lifang Zhang
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China
- University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Junling Meng
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China
| | - Fen Yao
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wenwen Zhang
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China
- University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xiaojuan Liu
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China
- University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Jian Meng
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China
- University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Hongjie Zhang
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China
- University of Science and Technology of China, Hefei, Anhui 230026, China
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Schweke D, Mordehovitz Y, Halabi M, Shelly L, Hayun S. Defect Chemistry of Oxides for Energy Applications. Adv Mater 2018; 30:e1706300. [PMID: 29855097 DOI: 10.1002/adma.201706300] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 03/14/2018] [Indexed: 06/08/2023]
Abstract
Oxides are widely used for energy applications, as solid electrolytes in various solid oxide fuel cell devices or as catalysts (often associated with noble metal particles) for numerous reactions involving oxidation or reduction. Defects are the major factors governing the efficiency of a given oxide for the above applications. In this paper, the common defects in oxide systems and external factors influencing the defect concentration and distribution are presented, with special emphasis on ceria (CeO2 ) based materials. It is shown that the behavior of a variety of oxide systems with respect to properties relevant for energy applications (conductivity and catalytic activity) can be rationalized by general considerations about the type and concentration of defects in the specific system. A new method based on transmission electron microscopy (TEM), recently reported by the authors for mapping space charge defects and measuring space charge potentials, is shown to be of potential importance for understanding conductivity mechanisms in oxides. The influence of defects on gas-surface reactions is exemplified on the interaction of CO2 and H2 O with ceria, by correlating between the defect distribution in the material and its adsorption capacity or splitting efficiency.
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Affiliation(s)
- Danielle Schweke
- Department of Materials Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva, 8410501, Israel
| | - Yuval Mordehovitz
- Department of Materials Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva, 8410501, Israel
| | - Mahdi Halabi
- Department of Materials Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva, 8410501, Israel
| | - Lee Shelly
- Department of Materials Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva, 8410501, Israel
| | - Shmuel Hayun
- Department of Materials Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva, 8410501, Israel
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Florea M, Avram D, Maraloiu VA, Cojocaru B, Tiseanu C. Heavy doping of ceria by wet impregnation: a viable alternative to bulk doping approaches. Nanoscale 2018; 10:18043-18054. [PMID: 30229790 DOI: 10.1039/c8nr03695k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
To avoid the deleterious effects of dopant segregation, synthesis methods that facilitate a homogenous dopant distribution in the ceria lattice were employed. Though doping ceria by wet impregnation was also credited to induce a homogeneous solid solution even in the heavy regime (concentration ≥20%, A. Corma, P. Atienzar, H. Garcia and J. Chane-Ching, Nat. Mater., 2004, 3, 394-397), no follow up investigation has been reported. Herein, we investigated ceria nanoparticles (1%Tm-CeO2 and 1%Eu-CeO2) wet-impregnated with trivalent rare-earth (Yb, 20%), bivalent (Ca, 20%) and isovalent (Zr, 30%) metals, followed by annealing in air. Homogeneity of the solid solutions of Yb-impregnated ceria was confirmed by a two-feature characterization toolbox that included X-ray diffraction, Raman spectroscopy, transmission electron microscopy, as well as up-conversion emission as a probe tool. Since the up-conversion emission of Tm was not detectable in the absence of Yb while its efficiency depends on the average distance between Yb and Tm ions, the Yb incorporation and its migration from the surface to the lattice bulk sites in wet-impregnated ceria can be "visualized" and compared with that of the Yb bulk-doped counterpart. The use of Eu luminescence as a local probe confirmed the homogeneity of solid solutions of Ca and Zr-impregnated ceria and also sustained the opposite roles of Ca and Zr as the repeller and the scavenger of oxygen vacancies, respectively. All these results suggested that heavy doping of ceria by wet impregnation with metals with +2, +3 and +4 valencies represent a facile alternative to conventional doping approaches. Therefore, the effects of the amount and the type of metal dopant on the structural properties of CeO2 could be investigated in a more systematic and probably a more reproducible manner, which would significantly increase the potential of ceria in catalysis and other applications.
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Affiliation(s)
- Mihaela Florea
- National Institute of Materials Physics, 405A Atomistilor Street, 077125 Magurele-Ilfov, Romania
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Abstract
The lattice constant has a crucial effect on the defect chemistry and defect kinetics in solid state materials. However, within density functional theory, some functionals perform badly in reproducing the experimental lattice constant. In this study, energies of defect formation, interaction and migration in the model system ceria were calculated for different lattice constants to investigate the impact on the energies. The GGA+U functional in the PBE and PBEsol parametrization as well as the hybrid functional HSE06 were applied and results are compared among these three commonly applied functionals. The results suggest a strong influence of the lattice constant on the energies especially regarding oxygen ion migration. This influence has an impact on the accurate prediction of defect properties from first principles but can also be utilized for specific tailoring of material properties by chemo-mechanical design. In addition, the issue of the correct lattice constant, which should be used in the defect calculations, is discussed in this paper.
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Affiliation(s)
- Steffen Grieshammer
- Helmholtz-Institut Münster (IEK-12), Forschungszentrum Jülich GmbH, Corrensstraße 46, 48149 Münster, Germany.
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Koettgen J, Grieshammer S, Hein P, Grope BOH, Nakayama M, Martin M. Understanding the ionic conductivity maximum in doped ceria: trapping and blocking. Phys Chem Chem Phys 2018; 20:14291-14321. [PMID: 29479588 DOI: 10.1039/c7cp08535d] [Citation(s) in RCA: 96] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Materials with high oxygen ion conductivity and low electronic conductivity are required for electrolytes in solid oxide fuel cells (SOFC) and high-temperature electrolysis (SOEC). A potential candidate for the electrolytes, which separate oxidation and reduction processes, is rare-earth doped ceria. The prediction of the ionic conductivity of the electrolytes and a better understanding of the underlying atomistic mechanisms provide an important contribution to the future of sustainable and efficient energy conversion and storage. The central aim of this paper is the detailed investigation of the relationship between defect interactions at the microscopic level and the macroscopic oxygen ion conductivity in the bulk of doped ceria. By combining ab initio density functional theory (DFT) with Kinetic Monte Carlo (KMC) simulations, the oxygen ion conductivity is predicted as a function of the doping concentration. Migration barriers are analyzed for energy contributions, which are caused by the interactions of dopants and vacancies with the migrating oxygen vacancy. We clearly distinguish between energy contributions that are either uniform for forward and backward jumps or favor one migration direction over the reverse direction. If the presence of a dopant changes the migration energy identically for forward and backward jumps, the resulting energy contribution is referred to as blocking. If the change in migration energy due to doping is different for forward and backward jumps of a specific ionic configuration, the resulting energy contributions are referred to as trapping. The influence of both effects on the ionic conductivity is analyzed: blocking determines the dopant fraction where the ionic conductivity exhibits the maximum. Trapping limits the maximum ionic conductivity value. In this way, a deeper understanding of the underlying mechanisms determining the influence of dopants on the ionic conductivity is obtained and the ionic conductivity is predicted more accurately. The detailed results and insights obtained here for doped ceria can be generalized and applied to other ion conductors that are important for SOFCs and SOECs as well as solid state batteries.
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Affiliation(s)
- Julius Koettgen
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany.
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Bharathi RN, Sankar S. Investigation of Transport Properties of Pr Doped Cerium Oxide Nanoparticles as a Solid Electrolyte for IT-SOFC Applications. J Inorg Organomet Polym Mater 2018. [DOI: 10.1007/s10904-018-0880-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Ahn J, Jang HW, Ji H, Kim H, Yoon KJ, Son JW, Kim BK, Lee HW, Lee JH. Identification of an Actual Strain-Induced Effect on Fast Ion Conduction in a Thin-Film Electrolyte. Nano Lett 2018; 18:2794-2801. [PMID: 29630383 DOI: 10.1021/acs.nanolett.7b04952] [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: 06/08/2023]
Abstract
Strain-induced fast ion conduction has been a research area of interest for nanoscale energy conversion and storage systems. However, because of significant discrepancies in the interpretation of strain effects, there remains a lack of understanding of how fast ionic transport can be achieved by strain effects and how strain can be controlled in a nanoscale system. In this study, we investigated strain effects on the ionic conductivity of Gd0.2Ce0.8O1.9-δ (100) thin films under well controlled experimental conditions, in which errors due to the external environment could not intervene during the conductivity measurement. In order to avoid any interference from perpendicular-to-surface defects, such as grain boundaries, the ionic conductivity was measured in the out-of-plane direction by electrochemical impedance spectroscopy analysis. With varying film thickness, we found that a thicker film has a lower activation energy of ionic conduction. In addition, careful strain analysis using both reciprocal space mapping and strain mapping in transmission electron microscopy shows that a thicker film has a higher tensile strain than a thinner film. Furthermore, the tensile strain of thicker film was mostly developed near a grain boundary, which indicates that intrinsic strain is dominant rather than epitaxial or thermal strain during thin-film deposition and growth via the Volmer-Weber (island) growth mode.
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Affiliation(s)
- Junsung Ahn
- High-Temperature Energy Materials Research Center , KIST , Seoul 02792 , Korea
- Department of Materials Science & Engineering, Research Institute of Advanced Materials , Seoul National University , Seoul 08826 , Korea
| | - Ho Won Jang
- Department of Materials Science & Engineering, Research Institute of Advanced Materials , Seoul National University , Seoul 08826 , Korea
| | - Hoil Ji
- High-Temperature Energy Materials Research Center , KIST , Seoul 02792 , Korea
| | - Hyoungchul Kim
- High-Temperature Energy Materials Research Center , KIST , Seoul 02792 , Korea
| | - Kyung Joong Yoon
- High-Temperature Energy Materials Research Center , KIST , Seoul 02792 , Korea
| | - Ji-Won Son
- High-Temperature Energy Materials Research Center , KIST , Seoul 02792 , Korea
- Division of Nano & Information Technology , KIST School, University of Science and Technology , Seoul 02792 , Korea
| | - Byung-Kook Kim
- High-Temperature Energy Materials Research Center , KIST , Seoul 02792 , Korea
| | - Hae-Weon Lee
- High-Temperature Energy Materials Research Center , KIST , Seoul 02792 , Korea
| | - Jong-Ho Lee
- High-Temperature Energy Materials Research Center , KIST , Seoul 02792 , Korea
- Division of Nano & Information Technology , KIST School, University of Science and Technology , Seoul 02792 , Korea
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Roshan AC, Irankhah A, Mahmoudizadeh M, Arandiyan H. Single-stage water gas shift reaction over structural modified Cu–Ce catalysts at medium temperatures: Synthesis and catalyst performance. Chem Eng Res Des 2018. [DOI: 10.1016/j.cherd.2018.02.038] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Galin MZ, Ivanov-Schitz AK, Mazo GN. Molecular Dynamics Simulation of the Structure and Ion Transport in the Ce1 – xGd x O2 – δ|YSZ Heterosystem. CRYSTALLOGR REP+ 2018. [DOI: 10.1134/s1063774518010078] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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50
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Abstract
The structural, vibrational, and diffusion properties of different ceria-based systems (including oxygen vacancies and rare-earth dopants (Sm or Gd)) have been examined using both first-principles density-functional theory calculations and finite-temperature molecular dynamics simulations.
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Affiliation(s)
- Dong-Hyuk Jung
- Department of Materials Science and Engineering
- Yonsei University
- Seoul 03722
- Korea
| | - Ji-Hwan Lee
- Department of Materials Science and Engineering
- Yonsei University
- Seoul 03722
- Korea
| | - Mehmet Emin Kilic
- Department of Materials Science and Engineering
- Yonsei University
- Seoul 03722
- Korea
| | - Aloysius Soon
- Department of Materials Science and Engineering
- Yonsei University
- Seoul 03722
- Korea
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