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Pożarowska E, Pleines L, Ewert M, Prieto MJ, Tănase LC, Caldas LDS, Tiwari A, Schmidt T, Falta J, Krasovskii E, Morales C, Flege JI. Preparation and stability of the hexagonal phase of samarium oxide on Ru(0001). Ultramicroscopy 2023; 250:113755. [PMID: 37216832 DOI: 10.1016/j.ultramic.2023.113755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Revised: 04/15/2023] [Accepted: 05/08/2023] [Indexed: 05/24/2023]
Abstract
We have used low-energy electron microscopy (LEEM), micro-illumination low-energy electron diffraction (µLEED) supported by ab initio calculations, and X-ray absorption spectroscopy (XAS) to investigate in-situ and in real-time the structural properties of Sm2O3 deposits grown on Ru(0001), a rare-earth metal oxide model catalyst. Our results show that samarium oxide grows in a hexagonal A-Sm2O3 phase on Ru(0001), exhibiting a (0001) oriented-top facet and (113) side facets. Upon annealing, a structural transition from the hexagonal to cubic phase occurs, in which the Sm cations exhibit the +3 oxidation state. The unexpected initial growth in the A-Sm2O3 hexagonal phase and its gradual transition to a mixture with cubic C-Sm2O3 showcases the complexity of the system and the critical role of the substrate in the stabilization of the hexagonal phase, which was previously reported only at high pressures and temperatures for bulk samaria. Besides, these results highlight the potential interactions that Sm could have with other catalytic compounds with respect to the here gathered insights on the preparation conditions and the specific compounds with which it interacts.
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Affiliation(s)
- Emilia Pożarowska
- Applied Physics and Semiconductor Spectroscopy, Brandenburg University of Technology Cottbus-Senftenberg, 03046 Cottbus, Germany
| | - Linus Pleines
- Institute of Solid State Physics, University of Bremen, 28359 Bremen, Germany
| | - Moritz Ewert
- Applied Physics and Semiconductor Spectroscopy, Brandenburg University of Technology Cottbus-Senftenberg, 03046 Cottbus, Germany
| | - Mauricio J Prieto
- Department of Interface Science, Fritz-Haber Institute, 14195 Berlin, Germany
| | - Liviu C Tănase
- Department of Interface Science, Fritz-Haber Institute, 14195 Berlin, Germany
| | | | - Aarti Tiwari
- Department of Interface Science, Fritz-Haber Institute, 14195 Berlin, Germany
| | - Thomas Schmidt
- Department of Interface Science, Fritz-Haber Institute, 14195 Berlin, Germany
| | - Jens Falta
- Institute of Solid State Physics, University of Bremen, 28359 Bremen, Germany
| | - Eugene Krasovskii
- Departamento de Polímeros y Materiales Avanzados: Física, Química y Tecnología, Universidad del Pais Vasco UPV/EHU, 20080 San Sebastián/Donostia, Spain; IKERBASQUE, Basque Foundation for Science, E-48013 Bilbao, Spain; Donostia International Physics Center (DIPC), E-20018 San Sebastián, Spain
| | - Carlos Morales
- Applied Physics and Semiconductor Spectroscopy, Brandenburg University of Technology Cottbus-Senftenberg, 03046 Cottbus, Germany
| | - Jan Ingo Flege
- Applied Physics and Semiconductor Spectroscopy, Brandenburg University of Technology Cottbus-Senftenberg, 03046 Cottbus, Germany.
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2
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Wang Y, Wang Y, Li L, Cui C, Liu X, Da. Costa P, Hu C. Syngas Production via CO 2 Reforming of Methane over Aluminum-Promoted NiO-10Al 2O 3-ZrO 2 Catalyst. ACS OMEGA 2021; 6:22383-22394. [PMID: 34497927 PMCID: PMC8412958 DOI: 10.1021/acsomega.1c03174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 08/09/2021] [Indexed: 06/13/2023]
Abstract
CO2 reforming of methane was studied at medium temperature (700 °C) using a GSHV of 48,000 h-1 over nickel catalysts supported on ZrO2 promoted by alumina. The catalysts were prepared by a one-step synthesis method and characterized by BET, H2-TPR, XRD, XPS, TEM, Raman spectroscopy, and TGA. The NiO-10Al2O3-ZrO2 catalyst exhibited higher catalytic performance in comparison with the NiO-ZrO2 catalyst. The enhancement of catalytic activity in dry reforming could be associated with the alterations in surface properties due to Al promotion. First, the Al promoter could modify the structure of ZrO2, leading to an increase of its pore volume and pore diameter. Second, the NiO-10Al2O3-ZrO2 catalyst exhibited high resistance to sintering. Third, the NiO-10Al2O3-ZrO2 catalyst showed high suppression to the loss of nickel during a long-term catalytic test. Finally, the addition of Al could inhibit the reduction of ZrO2 during the reduction and reaction, endowing further the stability.
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Affiliation(s)
- Ye Wang
- College
of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065, P. R. China
- Sorbonne
Université, Institut Jean Le Rond d’Alembert,
CNRS, 2 Place de la Gare de Ceinture, Saint-Cyr-L’Ecole 78210, France
| | - Yannan Wang
- Key
Laboratory of Green Chemistry and Technology, Ministry of Education,
College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, P. R. China
| | - Li Li
- Key
Laboratory of Green Chemistry and Technology, Ministry of Education,
College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, P. R. China
| | - Chaojun Cui
- College
of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065, P. R. China
| | - Xudong Liu
- Key
Laboratory of Green Chemistry and Technology, Ministry of Education,
College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, P. R. China
| | - Patrick Da. Costa
- Sorbonne
Université, Institut Jean Le Rond d’Alembert,
CNRS, 2 Place de la Gare de Ceinture, Saint-Cyr-L’Ecole 78210, France
| | - Changwei Hu
- College
of Chemical Engineering, Sichuan University, Chengdu, Sichuan 610065, P. R. China
- Key
Laboratory of Green Chemistry and Technology, Ministry of Education,
College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, P. R. China
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3
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M Ahmed E, Saber D, Abd ElAziz K, Alghtani AH, Felemban BF, Ali HT, Megahed M. Chitosan-based nanocomposites: preparation and characterization for food packing industry. MATERIALS RESEARCH EXPRESS 2021; 8:025017. [DOI: 10.1088/2053-1591/abe791] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
Abstract
In the present work, Cerium (IV)-Zirconium (IV) oxide nanoparticles (CeO4ZrNPs) was successfully dispersed into Chitosan/15Gelatin nanocomposites with different quantities. The obtained chitosan-based nanocomposites represented remarkable improvements in structural, morphological, mechanical, and thermal properties. Roughness increased from 74 nm to 6.4 nm, Young’s Modulus enhanced from 1.36 GPa to 2.99 GPa. The influence of dispersed CeO4ZrNPs contents on the phase transition temperature (T
g) and the non-isothermal degradation processes of chitosan-based nanocomposites were examined using Differential Scanning Galorimetry (DSC) with different heating rates. Kinetic parameters of the thermal degradation for chitosan-based nanocomposites were evaluated using Kissinger-Akahira-Sunose (KAS) and Kissenger (KIS) procedures. Chitosan-based nanocomposites showed an increase in the thermal degradation temperature with higher activation energies, indicating improved thermal stability. Thermal analysis demonstrated that chitosan-based nanocomposites became more ordered by increasing CeO4ZrNPs as inferred from the negative entropy increase. Moreover, the degradation of chitosan-based nanocomposites has been described as a non-spontaneous process. The resulting information is particularly important in applications in which there is a need to obtain chitosan nanocomposites with improved mechanical and thermal properties such as food packing industry.
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4
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Tuning Polarity of Cu-O Bond in Heterogeneous Cu Catalyst to Promote Additive-free Hydroboration of Alkynes. Chem 2020. [DOI: 10.1016/j.chempr.2019.12.021] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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5
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Jain R, Dubey A, Ghosalya MK, Gopinath CS. Gas–solid interaction of H2–Ce0.95Zr0.05O2: new insights into surface participation in heterogeneous catalysis. Catal Sci Technol 2016. [DOI: 10.1039/c5cy01428j] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A conventional gas–solid interaction has been explored with valence band APPES and changes in molecular vibrations of hydrogen.
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Affiliation(s)
- Ruchi Jain
- Catalysis Division
- National Chemical Laboratory
- Pune 411 008
- India
| | - Anjani Dubey
- Catalysis Division
- National Chemical Laboratory
- Pune 411 008
- India
| | | | - Chinnakonda S. Gopinath
- Catalysis Division
- National Chemical Laboratory
- Pune 411 008
- India
- Centre of Excellence on Surface Science
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6
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Lei W, Zhang T, Gu L, Liu P, Rodriguez JA, Liu G, Liu M. Surface-Structure Sensitivity of CeO2 Nanocrystals in Photocatalysis and Enhancing the Reactivity with Nanogold. ACS Catal 2015. [DOI: 10.1021/acscatal.5b00620] [Citation(s) in RCA: 139] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Wanying Lei
- National Center
for Nanoscience and Technology, Beijing 100190, China
| | - Tingting Zhang
- National Center
for Nanoscience and Technology, Beijing 100190, China
| | - Lin Gu
- Beijing
National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Ping Liu
- Chemistry
Department, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - José A. Rodriguez
- Chemistry
Department, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Gang Liu
- National Center
for Nanoscience and Technology, Beijing 100190, China
| | - Minghua Liu
- National Center
for Nanoscience and Technology, Beijing 100190, China
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7
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Lu X, Wang W, Wei S, Guo C, Shao Y, Zhang M, Deng Z, Zhu H, Guo W. Initial reduction of CO2 on perfect and O-defective CeO2 (111) surfaces: towards CO or COOH? RSC Adv 2015. [DOI: 10.1039/c5ra17825h] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
CO2 hydrogenation towards COOH is more favorable on perfect CeO2 (111) surface, whereas reductive dissociation of CO2 is predominant on O-defective surface. The O vacancy promotes reductive dissociation of CO2 on O-defective CeO2 (111) surface.
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Affiliation(s)
- Xiaoqing Lu
- College of Science
- China University of Petroleum
- Qingdao
- People's Republic of China
| | - Weili Wang
- College of Science
- China University of Petroleum
- Qingdao
- People's Republic of China
| | - Shuxian Wei
- College of Science
- China University of Petroleum
- Qingdao
- People's Republic of China
| | - Chen Guo
- College of Science
- China University of Petroleum
- Qingdao
- People's Republic of China
| | - Yang Shao
- College of Science
- China University of Petroleum
- Qingdao
- People's Republic of China
| | - Mingmin Zhang
- College of Science
- China University of Petroleum
- Qingdao
- People's Republic of China
| | - Zhigang Deng
- College of Science
- China University of Petroleum
- Qingdao
- People's Republic of China
| | - Houyu Zhu
- College of Science
- China University of Petroleum
- Qingdao
- People's Republic of China
| | - Wenyue Guo
- College of Science
- China University of Petroleum
- Qingdao
- People's Republic of China
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8
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Zhao P, Kiriya D, Azcatl A, Zhang C, Tosun M, Liu YS, Hettick M, Kang JS, McDonnell S, Santosh KC, Guo J, Cho K, Wallace RM, Javey A. Air stable p-doping of WSe2 by covalent functionalization. ACS NANO 2014; 8:10808-14. [PMID: 25229426 DOI: 10.1021/nn5047844] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Covalent functionalization of transition metal dichalcogenides (TMDCs) is investigated for air-stable chemical doping. Specifically, p-doping of WSe(2) via NOx chemisorption at 150 °C is explored, with the hole concentration tuned by reaction time. Synchrotron based soft X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) depict the formation of various WSe(2-x-y)O(x)N(y) species both on the surface and interface between layers upon chemisorption reaction. Ab initio simulations corroborate our spectroscopy results in identifying the energetically favorable complexes, and predicting WSe(2):NO at the Se vacancy sites as the predominant dopant species. A maximum hole concentration of ∼ 10(19) cm(-3) is obtained from XPS and electrical measurements, which is found to be independent of WSe(2) thickness. This degenerate doping level facilitates 5 orders of magnitude reduction in contact resistance between Pd, a common p-type contact metal, and WSe(2). More generally, the work presents a platform for manipulating the electrical properties and band structure of TMDCs using covalent functionalization.
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Affiliation(s)
- Peida Zhao
- Electrical Engineering and Computer Sciences, University of California , Berkeley, California 94720, United States
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9
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Liu X, Liu W, Zhang X, Han L, Zhang C, Yang Y. Zr-doped CeO2Hollow slightly-truncated nano-octahedrons: One-pot synthesis, characterization and their application in catalysis of CO oxidation. CRYSTAL RESEARCH AND TECHNOLOGY 2014. [DOI: 10.1002/crat.201400039] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Xiufang Liu
- Key Laboratory for Special Functional Aggregate Materials of Education Ministry; School of Chemistry and Chemical Engineering; Shandong University; Jinan 250100 P. R. China
| | - Wei Liu
- Key Laboratory for Special Functional Aggregate Materials of Education Ministry; School of Chemistry and Chemical Engineering; Shandong University; Jinan 250100 P. R. China
| | - Xueying Zhang
- Key Laboratory for Special Functional Aggregate Materials of Education Ministry; School of Chemistry and Chemical Engineering; Shandong University; Jinan 250100 P. R. China
| | - Lu Han
- Key Laboratory for Special Functional Aggregate Materials of Education Ministry; School of Chemistry and Chemical Engineering; Shandong University; Jinan 250100 P. R. China
| | - Cong Zhang
- Key Laboratory for Special Functional Aggregate Materials of Education Ministry; School of Chemistry and Chemical Engineering; Shandong University; Jinan 250100 P. R. China
| | - Yanzhao Yang
- Key Laboratory for Special Functional Aggregate Materials of Education Ministry; School of Chemistry and Chemical Engineering; Shandong University; Jinan 250100 P. R. China
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10
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Lee YH, Chen JM, Lee JF, Kao HCI. XANES Spectroscopic Studies of the Phase Transition in Gd2Zr2O7. J CHIN CHEM SOC-TAIP 2013. [DOI: 10.1002/jccs.200900080] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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11
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Affiliation(s)
- Eric W. McFarland
- Department
of Chemical Engineering, and ‡Department of Chemistry and Biochemistry, University of California, Santa Barbara,
California 93106, United States
| | - Horia Metiu
- Department
of Chemical Engineering, and ‡Department of Chemistry and Biochemistry, University of California, Santa Barbara,
California 93106, United States
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12
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Ji S, Chang I, Lee YH, Park J, Paek JY, Lee MH, Cha SW. Fabrication of low-temperature solid oxide fuel cells with a nanothin protective layer by atomic layer deposition. NANOSCALE RESEARCH LETTERS 2013; 8:48. [PMID: 23342963 PMCID: PMC3564701 DOI: 10.1186/1556-276x-8-48] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Accepted: 01/04/2013] [Indexed: 06/01/2023]
Abstract
Anode aluminum oxide-supported thin-film fuel cells having a sub-500-nm-thick bilayered electrolyte comprising a gadolinium-doped ceria (GDC) layer and an yttria-stabilized zirconia (YSZ) layer were fabricated and electrochemically characterized in order to investigate the effect of the YSZ protective layer. The highly dense and thin YSZ layer acted as a blockage against electron and oxygen permeation between the anode and GDC electrolyte. Dense GDC and YSZ thin films were fabricated using radio frequency sputtering and atomic layer deposition techniques, respectively. The resulting bilayered thin-film fuel cell generated a significantly higher open circuit voltage of approximately 1.07 V compared with a thin-film fuel cell with a single-layered GDC electrolyte (approximately 0.3 V).
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Affiliation(s)
- Sanghoon Ji
- Graduate School of Convergence Science and Technology, Seoul National University, 864-1 Lui Dong, Yeongtong-Gu, Suwon, Gyeonggi-Do, 433-270, South Korea
| | - Ikwhang Chang
- Graduate School of Convergence Science and Technology, Seoul National University, 864-1 Lui Dong, Yeongtong-Gu, Suwon, Gyeonggi-Do, 433-270, South Korea
| | - Yoon Ho Lee
- School of Mechanical and Aerospace Engineering, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul, 151-742, South Korea
| | - Joonho Park
- School of Mechanical and Aerospace Engineering, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul, 151-742, South Korea
| | - Jun Yeol Paek
- School of Mechanical and Aerospace Engineering, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul, 151-742, South Korea
| | - Min Hwan Lee
- School of Engineering, University of California, Merced, 5200 North Lake Road, Merced, CA, 95343, USA
| | - Suk Won Cha
- School of Mechanical and Aerospace Engineering, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul, 151-742, South Korea
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13
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Fang Q, Liang X. CeO2–Al2O3, CeO2–SiO2, CeO2–TiO2 core-shell spheres: formation mechanisms and UV absorption. RSC Adv 2012. [DOI: 10.1039/c2ra01331b] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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14
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Ghoshal T, Fleming PG, Holmes JD, Morris MA. The stability of “Ce2O3” nanodots in ambient conditions: a study using block copolymer templated structures. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm35073d] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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15
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Ferrari V, Llois AM, Vildosola V. Co-doped ceria: tendency towards ferromagnetism driven by oxygen vacancies. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:276002. [PMID: 21399268 DOI: 10.1088/0953-8984/22/27/276002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We perform an electronic structure study for cerium oxide homogeneously doped with cobalt impurities, focusing on the role played by oxygen vacancies and structural relaxation. By means of full-potential ab initio methods, we explore the possibility of ferromagnetism as observed in recent experiments. Our results indicate that oxygen vacancies seem to be crucial for the appearance of a ferromagnetic alignment among Co impurities, obtaining an increasing tendency towards ferromagnetism with growing vacancy concentration. However, the estimated couplings cannot explain the experimentally observed room-temperature ferromagnetism. In this systematic study, we draw relevant conclusions regarding the location of the oxygen vacancies and the magnetic couplings involved. In particular, we find that oxygen vacancies tend to nucleate in the neighborhood of Co impurities and we get a remarkably strong ferromagnetic coupling between Co atoms and the Ce(3+) neighboring ions. The calculated magnetic moments per cell depend on the degree of reduction, which could explain the wide spread in the magnetization values observed in the experiments.
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Affiliation(s)
- V Ferrari
- Departamento de Física and INN, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica, Gral. Paz 1499, 1650 San Martín, Buenos Aires, Argentina
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Chen HT, Chang JG. Oxygen vacancy formation and migration in Ce1−xZrxO2 catalyst: A DFT+U calculation. J Chem Phys 2010; 132:214702. [DOI: 10.1063/1.3429314] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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17
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Zhang G, Zhao Z, Liu J, Jiang G, Duan A, Zheng J, Chen S, Zhou R. Three dimensionally ordered macroporous Ce1−xZrxO2solid solutions for diesel soot combustion. Chem Commun (Camb) 2010; 46:457-9. [DOI: 10.1039/b915027g] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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18
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Atribak I, Bueno-López A, García-García A, Azambre B. Contributions of surface and bulk heterogeneities to the NO oxidation activities of ceria–zirconia catalysts with composition Ce0.76Zr0.24O2 prepared by different methods. Phys Chem Chem Phys 2010; 12:13770-9. [DOI: 10.1039/c0cp00540a] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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19
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Yang H, Mao X, Guo Y, Wang D, Ge G, Yang R, Qiu X, Yang Y, Wang C, Wang Y, Liu G. Porous α-Fe2O3 nanostructures with branched topology: growth, formation mechanism, and properties. CrystEngComm 2010. [DOI: 10.1039/b921618a] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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WEI Y, LIU J, ZHAO Z, JIANG G, DUAN A, HE H, WANG X. Preparation and Characterization of Co0.2/Ce1-xZrxO2 Catalysts and Their Catalytic Activity for Soot Combustion. CHINESE JOURNAL OF CATALYSIS 2010. [DOI: 10.1016/s1872-2067(09)60050-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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21
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Park JB, Graciani J, Evans J, Stacchiola D, Ma S, Liu P, Nambu A, Sanz JF, Hrbek J, Rodriguez JA. High catalytic activity of Au/CeOx/TiO2(110) controlled by the nature of the mixed-metal oxide at the nanometer level. Proc Natl Acad Sci U S A 2009; 106:4975-80. [PMID: 19276120 PMCID: PMC2664040 DOI: 10.1073/pnas.0812604106] [Citation(s) in RCA: 240] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2008] [Indexed: 11/18/2022] Open
Abstract
Mixed-metal oxides play a very important role in many areas of chemistry, physics, materials science, and geochemistry. Recently, there has been a strong interest in understanding phenomena associated with the deposition of oxide nanoparticles on the surface of a second (host) oxide. Here, scanning tunneling microscopy, photoemission, and density-functional calculations are used to study the behavior of ceria nanoparticles deposited on a TiO(2)(110) surface. The titania substrate imposes nontypical coordination modes on the ceria nanoparticles. In the CeO(x)/TiO(2)(110) systems, the Ce cations adopt an structural geometry and an oxidation state (+3) that are quite different from those seen in bulk ceria or for ceria nanoparticles deposited on metal substrates. The increase in the stability of the Ce(3+) oxidation state leads to an enhancement in the chemical and catalytic activity of the ceria nanoparticles. The codeposition of ceria and gold nanoparticles on a TiO(2)(110) substrate generates catalysts with an extremely high activity for the production of hydrogen through the water-gas shift reaction (H(2)O + CO --> H(2) + CO(2)) or for the oxidation of carbon monoxide (2CO + O(2) --> 2CO(2)). The enhanced stability of the Ce(3+) state is an example of structural promotion in catalysis described here on the atomic level. The exploration of mixed-metal oxides at the nanometer level may open avenues for optimizing catalysts through stabilization of unconventional surface structures with special chemical activity.
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Affiliation(s)
- Joon B. Park
- Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973
| | - Jesus Graciani
- Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973
| | - Jaime Evans
- Facultad de Ciencias, Universidad Central de Venezuela, Caracas, 1020-A, Venezuela; and
| | - Dario Stacchiola
- Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973
| | - Shuguo Ma
- Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973
| | - Ping Liu
- Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973
| | - Akira Nambu
- Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973
| | | | - Jan Hrbek
- Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973
| | - José A. Rodriguez
- Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973
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22
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Nakayama M, Martin M. First-principles study on defect chemistry and migration of oxide ions in ceria doped with rare-earth cations. Phys Chem Chem Phys 2009; 11:3241-9. [DOI: 10.1039/b900162j] [Citation(s) in RCA: 201] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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23
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Shi X, Ji S, Wang K, Li C. Oxidative Dehydrogenation of Ethane over Ce-based Monolithic Catalysts using CO2 as Oxidant. Catal Letters 2008. [DOI: 10.1007/s10562-008-9648-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Reddy BM, Bharali P, Seo YH, Prasetyanto EA, Park SE. Surfactant-Controlled and Microwave-Assisted Synthesis of Highly Active Ce x Zr1−x O2 Nano-Oxides for CO Oxidation. Catal Letters 2008. [DOI: 10.1007/s10562-008-9591-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Opalka SM, Vanderspurt TH, Radhakrishnan R, She Y, Willigan RR. Design of water gas shift catalysts for hydrogen production in fuel processors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2008; 20:064237. [PMID: 21693898 DOI: 10.1088/0953-8984/20/6/064237] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Low sulfur hydrocarbon fuels can be converted to fuel cell grade H(2) using a compact fuel processor architecture. The necessary high volumetric activity water gas shift (WGS) Pt on ceria-zirconia catalysts reacts CO-rich reformate with steam to yield H(2) and CO(2). Such highly selective, non-pyrophoric noble metal/Ce([1-(x+y)])Zr(x)Dp(y)O(2) catalysts were developed through coordinated atomic modeling, syntheses, structural characterization, kinetic performance tests, and micro-kinetic analyses. Density functional simulations made with the VASP code suggested that the undoped catalyst WGS activity would be limited by the strong binding of CO intermediates, blocking the reoxidation of the reduced oxide by water. These predictions were confirmed by in situ cylindrical internal reflection-Fourier transform infrared spectroscopy and by micro-kinetic analyses of the micro-reactor results. Atomic simulations were used to evaluate the impact transition metal dopants had on the surface chemistry of cubic ceria-zirconia. VASP predicted that acidic transition metal dopants such as Nb, Mo, Ta, and W would increase the oxide surface affinity for water and thus increase the turnover rate of the catalyst. The efficacy of Mo-doped ceria-zirconia compositions was confirmed at lower temperatures in replicated catalyst synthesis-reactor studies.
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Affiliation(s)
- S M Opalka
- United Technologies Research Center, East Hartford, CT 06108, USA
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28
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Liang X, Wang X, Zhuang Y, Xu B, Kuang S, Li Y. Formation of CeO2−ZrO2 Solid Solution Nanocages with Controllable Structures via Kirkendall Effect. J Am Chem Soc 2008; 130:2736-7. [DOI: 10.1021/ja7109629] [Citation(s) in RCA: 267] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xin Liang
- Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
| | - Xun Wang
- Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
| | - Yuan Zhuang
- Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
| | - Biao Xu
- Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
| | - Simin Kuang
- Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
| | - Yadong Li
- Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
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Yang Z, Woo TK, Hermansson K. Effects of Zr doping on stoichiometric and reduced ceria: A first-principles study. J Chem Phys 2006; 124:224704. [PMID: 16784298 DOI: 10.1063/1.2200354] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The Zr doping in CeO(2) may change the reduction properties and therefore the redox properties of CeO(2). Using first-principles density functional theory with the inclusion of on-site Coulomb interaction for a 96-atom supercell, these effects are studied by comparing the differences in atomic structures, electronic structures, and reduction energies of the doped CeO(2) and those of the nondoped CeO(2). It is found that (1) Zr doping of the ceria structure results in important modifications involving nonequivalent O atoms; (2) the oxygen anions (still four-coordinated) next to the doping center show considerably lower reduction energies (by 0.6 eV) and larger displacements ("higher mobilities"); (3) an O vacancy is most easily created close to the Zr centers, therefore the Zr-doping centers might serve as nucleation centers for vacancy clustering; and (4) the electrons left by the released oxygen localize on two Ce cations neighboring the vacancy, which results in the reduction of two Ce(4+) ions.
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Affiliation(s)
- Zongxian Yang
- College of Physics and Information Engineering, Henan Normal University, Xinxiang, Henan 453007, People's Republic of China
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31
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Chen H, Aleksandrov A, Zha S, Liu M, Orlando TM. Highly Efficient Electron Stimulated Desorption of O+ from Gadolinia-Doped Ceria Surfaces. J Phys Chem B 2006; 110:10779-84. [PMID: 16771326 DOI: 10.1021/jp0601264] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Highly efficient electron stimulated desorption of O+ from gadolinia-doped ceria (GDC) surfaces annealed at 850 K in ultrahigh vacuum is observed and investigated. O+ desorption has a major threshold of approximately 40 eV and an intrinsic kinetic energy of approximately 5.6 eV. Since the threshold energy is close to Ce 5s and Gd 5s core levels, Auger decay of core holes is likely associated with O+ desorption from sites related to oxygen vacancies. The interactions of water and molecular oxygen with GDC surfaces result in a decrease in O+ desorption, suggesting that water and oxygen molecules adsorb mainly to oxygen vacancies. The dependence of O+ kinetic energies on the incident electron energy and temperature reveals surface charging as a result of electron trapping, hole trapping, and electron-hole recombination. The activation energy for surface charge dissipation is found to be 0.43 eV, close to the activation energy for ionic conduction (0.47 to 0.6 eV) in the same material.
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Affiliation(s)
- Haiyan Chen
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
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32
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Wang X, Rodriguez JA, Hanson JC, Pérez M, Evans J. In situtime-resolved characterization of Au–CeO2 and AuOx–CeO2 catalysts during the water-gas shift reaction: Presence of Au and O vacancies in the active phase. J Chem Phys 2005; 123:221101. [PMID: 16375458 DOI: 10.1063/1.2136876] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Synchrotron-based in situ time-resolved x-ray diffraction and x-ray absorption spectroscopies were used to study the behavior of nanostructured {Au+AuO(x)}-CeO(2) catalysts under the water-gas shift (WGS) reaction. At temperatures above 250 degrees C, a complete AuO(x)-->Au transformation was observed with high catalytic activity. Photoemission results for the oxidation and reduction of Au nanoparticles supported on rough ceria films or a CeO(2)(111) single crystal corroborate that cationic Au(delta+) species cannot be the key sites responsible for the WGS activity at high temperatures. The rate determining steps for the WGS seem to occur at the gold-ceria interface, with the active sites involving small gold clusters (<2 nm) and O vacancies.
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Affiliation(s)
- X Wang
- Department of Chemistry, Brookhaven National Laboratory, Upton, NY 11973, USA.
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33
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Wang X, Rodriguez JA, Hanson JC, Gamarra D, Martínez-Arias A, Fernandez-García M. Unusual Physical and Chemical Properties of Cu in Ce1-xCuxO2 Oxides. J Phys Chem B 2005; 109:19595-603. [PMID: 16853534 DOI: 10.1021/jp051970h] [Citation(s) in RCA: 235] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The structural and electronic properties of Ce(1-x)Cu(x)O(2) nano systems prepared by a reverse microemulsion method were characterized with synchrotron-based X-ray diffraction, X-ray absorption spectroscopy, Raman spectroscopy, and density functional calculations. The Cu atoms embedded in ceria had an oxidation state higher than those of the cations in Cu(2)O or CuO. The lattice of the Ce(1)(-x)Cu(x)O(2) systems still adopted a fluorite-type structure, but it was highly distorted with multiple cation-oxygen distances with respect to the single cation-oxygen bond distance seen in pure ceria. The doping of CeO(2) with copper introduced a large strain into the oxide lattice and favored the formation of O vacancies, leading to a Ce(1-x)Cu(x)O(2-y) stoichiometry for our materials. Cu approached the planar geometry characteristic of Cu(II) oxides, but with a strongly perturbed local order. The chemical activities of the Ce(1-x)Cu(x)O(2) nanoparticles were tested using the reactions with H(2) and O(2) as probes. During the reduction in hydrogen, an induction time was observed and became shorter after raising the reaction temperature. The fraction of copper that could be reduced in the Ce(1-x)Cu(x)O(2) oxides also depended strongly on the reaction temperature. A comparison with data for the reduction of pure copper oxides indicated that the copper embedded in ceria was much more difficult to reduce. The reduction of the Ce(1-x)Cu(x)O(2) nanoparticles was rather reversible, without the generation of a significant amount of CuO or Cu(2)O phases during reoxidation. This reversible process demonstrates the unusual structural and chemical properties of the Cu-doped ceria materials.
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Affiliation(s)
- Xianqin Wang
- Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973, USA
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Nanosized CeO2–SiO2, CeO2–TiO2, and CeO2–ZrO2 Mixed Oxides: Influence of Supporting Oxide on Thermal Stability and Oxygen Storage Properties of Ceria. CATALYSIS SURVEYS FROM ASIA 2005. [DOI: 10.1007/s10563-005-7552-1] [Citation(s) in RCA: 211] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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35
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Deiner LJ, Kang DH, Friend CM. Low-Temperature Reduction of NO2 on Oxidized Mo(110). J Phys Chem B 2005; 109:12826-31. [PMID: 16852590 DOI: 10.1021/jp046249a] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The reactions of nitrogen dioxide (NO(2)) were investigated on oxidized Mo(110) containing both chemisorbed oxygen and a thin film oxide. NO(2) reacts on both oxidized Mo(110) surfaces via a combination of reversible adsorption and reduction to NO, N(2), and trace amounts of N(2)O below 200 K. On the surface containing chemisorbed O, there is some complete dissociation of NO(2) to yield N(a) and O(a). N(2) forms at high temperatures through atom combination. On both surfaces, NO is the predominant product of NO(2) reduction. However, the chemisorbed layer which has a low oxidation state, and hence a greater capacity to accept oxygen, more effectively reduces NO(2). The selectivity for N(2) formation over N(2)O is greater for NO(2) as compared with NO on both surfaces studied. The selectivity changes are largely attributed to an increase in the concentration of Mo=O species and a change in the distribution of oxygen on the surface. Notably, more oxygen, in particular Mo=O moieties, is deposited by NO(2) reaction than by O(2) reaction, indicating that NO(2) is a stronger oxidant. The fact that there are several N-containing species on the surface at low temperatures may also affect the product distribution. On both surfaces, N(2)O(4), NO(2), and NO are identified by infrared spectroscopy upon adsorption at 100 K. All N(2)O(4) desorbs by 200 K, leaving only NO(2) and NO on the surface. Infrared spectroscopy of NO(2) on (18)O-labeled surfaces provides evidence for oxygen transfer or exchange between different types of sites even at low temperatures.
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Affiliation(s)
- L J Deiner
- Department of Chemistry and Division of Engineering and Applied Science, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, USA
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36
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Wang X, Hanson JC, Rodriguez JA, Belver C, Fernández-García M. The structural and electronic properties of nanostructured Ce1−x−yZrxTbyO2 ternary oxides: Unusual concentration of Tb3+ and metal↔oxygen↔metal interactions. J Chem Phys 2005; 122:154711. [PMID: 15945660 DOI: 10.1063/1.1883631] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Ceria-based ternary oxides are widely used in many areas of chemistry, physics, and materials science. Synchrotron-based time-resolved x-ray diffraction, x-ray absorption near-edge spectroscopy (XANES), Raman spectroscopy, and density-functional calculations were used to study the structural and electronic properties of Ce-Zr-Tb oxide nanoparticles. The nanoparticles were synthesized following a novel microemulsion method and had sizes in the range of 4-7 nm. The Ce1-x-yZrxTbyO2 ternary systems exhibit a complex behavior that cannot be predicted as a simple extrapolation of the properties of Ce1-xZrxO2, Ce1-xTbxO2, or the individual oxides (CeO2, ZrO2, and TbO2). The doping of ceria with Zr and Tb induces a decrease in the unit cell, but there are large positive deviations with respect to the cell parameters predicted by Vegard's rule for ideal solid solutions. The presence of Zr and Tb generates strain in the ceria lattice through the creation of crystal imperfections and O vacancies. The O K-edge and Tb LIII-edge XANES spectra for the Ce1-x-yZrxTbyO2 nanoparticles point to the existence of distinctive electronic properties. In Ce1-x-yZrxTbyO2 there is an unexpected high concentration of Tb3+, which is not seen in TbO2 or Ce1-xTbxO2 and enhances the chemical reactivity of the ternary oxide. Tb<-->O<-->Zr interactions produce a stabilization of the Tb(4f,5d) states that is responsible for the high concentration of Tb(3+) cations. The behavior of Ce1-x-yZrxTbyO2 illustrates how important can be metal<-->oxygen<-->metal interactions for determining the structural, electronic, and chemical properties of a ternary oxide.
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Affiliation(s)
- Xianqin Wang
- Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973, USA
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37
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Borchert H, Frolova YV, Kaichev VV, Prosvirin IP, Alikina GM, Lukashevich AI, Zaikovskii VI, Moroz EM, Trukhan SN, Ivanov VP, Paukshtis EA, Bukhtiyarov VI, Sadykov VA. Electronic and Chemical Properties of Nanostructured Cerium Dioxide Doped with Praseodymium. J Phys Chem B 2005; 109:5728-38. [PMID: 16851621 DOI: 10.1021/jp045828c] [Citation(s) in RCA: 150] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nanostructured doped ceria is a prospective material for catalytic applications such as the construction of membranes with mixed electronic and ionic conductivity for effective syngas production. In this article, the surface properties of nanostructured ceria doped with praseodymium have been studied by X-ray photoelectron spectroscopy, secondary ion mass spectrometry, and Fourier transform infrared spectroscopy of adsorbed carbon monoxide. The effects of supporting 1.4 wt % Pt as well as structural changes upon the reduction of the samples with methane have been investigated. While in samples without supported platinum, mainly praseodymium cations are reduced in a methane atmosphere; stronger reduction of cerium cations was found in the case of surface modification with Pt. The structural differences correlate with results from temperature-programmed reaction experiments with methane. Explanations are discussed in terms of different reaction mechanisms.
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Affiliation(s)
- Holger Borchert
- Boreskov Institute of Catalysis SB RAS and Novosibirsk State University, Novosibirsk, Russia
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38
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Rodriguez J, Wang X, Liu G, Hanson J, Hrbek J, Peden C, Iglesias-Juez A, Fernández-García M. Physical and chemical properties of Ce1−xZrxO2 nanoparticles and Ce1−xZrxO2(111) surfaces: synchrotron-based studies. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/j.molcata.2004.09.069] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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39
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Yang Z, Woo TK, Hermansson K. Strong and weak adsorption of CO on CeO2 surfaces from first principles calculations. Chem Phys Lett 2004. [DOI: 10.1016/j.cplett.2004.08.078] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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40
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Fernández-García M, Martínez-Arias A, Hanson JC, Rodriguez JA. Nanostructured Oxides in Chemistry: Characterization and Properties. Chem Rev 2004; 104:4063-104. [PMID: 15352786 DOI: 10.1021/cr030032f] [Citation(s) in RCA: 387] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- M Fernández-García
- Instituto de Catálisis y Petroleoquímica, CSIC, C/ Marie Curie s/n, Campus Cantoblanco, 28049-Madrid, Spain
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41
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Diagne C, Idriss H, Pearson K, Gómez-García MA, Kiennemann A. Efficient hydrogen production by ethanol reforming over Rh catalysts. Effect of addition of Zr on CeO2 for the oxidation of CO to CO2. CR CHIM 2004. [DOI: 10.1016/j.crci.2004.03.004] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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42
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Corma A, Atienzar P, García H, Chane-Ching JY. Hierarchically mesostructured doped CeO2 with potential for solar-cell use. NATURE MATERIALS 2004; 3:394-7. [PMID: 15146175 DOI: 10.1038/nmat1129] [Citation(s) in RCA: 355] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2003] [Accepted: 04/02/2004] [Indexed: 05/09/2023]
Abstract
Many properties provided by supramolecular chemistry, nanotechnology and catalysis only appear in solids exhibiting large surface areas and regular porosity at the nanometre scale. In nanometre-sized particles, the ratio of the number of atoms in the surface to the number in the bulk is much larger than for micrometre-sized materials, and this can lead to novel properties. Here we report the preparation of a hierarchically structured mesoporous material from nanoparticles of CeO(2) of strictly uniform size. The synthesis involves self-assembly of these 5-nm CeO(2) pre-treated nanoparticles in the presence of a structure directing agent (poly(alkylene oxide) block polymer). The walls of this hexagonal structured CeO(2) material are formed from the primary nanoparticles. The material possesses large pore volumes, high surface areas, and marked thermal stability, allowing it to be easily doped after synthesis whilst maintaining textural and mechanical integrity. It also exhibits a photovoltaic response, which is directly derived from the nanometric particle size-normal CeO(2) does not show this response. We have constructed operational organic-dye-free solar cells using nanometric ceria particles (in both mesostructured or amorphous forms) as the active component, and find efficiencies that depend on the illuminating power.
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Affiliation(s)
- Avelino Corma
- Instituto de Tecnología Química, UPV-CSIC, Universidad Politécnica de Valencia, Avda. de los Naranjos s/n, 46022 Valencia, Spain.
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43
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Yang Z, Woo TK, Baudin M, Hermansson K. Atomic and electronic structure of unreduced and reduced CeO2 surfaces: A first-principles study. J Chem Phys 2004; 120:7741-9. [PMID: 15267687 DOI: 10.1063/1.1688316] [Citation(s) in RCA: 313] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The atomic and electronic structure of (111), (110), and (100) surfaces of ceria (CeO2) were studied using density-functional theory within the generalized gradient approximation. Both stoichiometric surfaces and surfaces with oxygen vacancies (unreduced and reduced surfaces, respectively) have been examined. It is found that the (111) surface is the most stable among the considered surfaces, followed by (110) and (100) surfaces, in agreement with experimental observations and previous theoretical results. Different features of relaxation are found for the three surfaces. While the (111) surface undergoes very small relaxation, considerably larger relaxations are found for the (110) and (100) surfaces. The formation of an oxygen vacancy is closely related to the surface structure and occurs more easily for the (110) surface than for (111). The preferred vacancy location is in the surface layer for CeO2(110) and in the subsurface layer (the second O-atomic layer) for CeO2(111). For both surfaces, the O vacancy forms more readily than in the bulk. An interesting oscillatory behavior is found for the vacancy formation energy in the upper three layers of CeO2(111). Analysis of the reduced surfaces suggests that the additional charge resulting from the formation of the oxygen vacancies is localized in the first three layers of the surface. Furthermore, they are not only trapped in the 4f states of cerium.
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Affiliation(s)
- Zongxian Yang
- Department of Chemistry, The University of Western Ontario, London, Ontario, Canada N6A 5B7
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44
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Pushkarev VV, Kovalchuk VI, d'Itri JL. Probing Defect Sites on the CeO2 Surface with Dioxygen. J Phys Chem B 2004. [DOI: 10.1021/jp0311254] [Citation(s) in RCA: 311] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Vladimir V. Pushkarev
- Department of Chemical Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Vladimir I. Kovalchuk
- Department of Chemical Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Julie L. d'Itri
- Department of Chemical Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
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45
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Liu G, Rodriguez JA, Chang Z, Hrbek J, Peden CHF. Adsorption and Reaction of SO2 on Model Ce1 - xZrxO2(111) Catalysts. J Phys Chem B 2004. [DOI: 10.1021/jp030808g] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gang Liu
- Chemistry Department, Brookhaven National Laboratory, Upton, New York 11953
| | - José A. Rodriguez
- Chemistry Department, Brookhaven National Laboratory, Upton, New York 11953
| | - Zhipeng Chang
- Chemistry Department, Brookhaven National Laboratory, Upton, New York 11953
| | - Jan Hrbek
- Chemistry Department, Brookhaven National Laboratory, Upton, New York 11953
| | - Charles H. F. Peden
- Chemical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352
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46
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Reddy BM, Khan A, Yamada Y, Kobayashi T, Loridant S, Volta JC. Structural Characterization of CeO2−MO2 (M = Si4+, Ti4+, and Zr4+) Mixed Oxides by Raman Spectroscopy, X-ray Photoelectron Spectroscopy, and Other Techniques. J Phys Chem B 2003. [DOI: 10.1021/jp0358376] [Citation(s) in RCA: 148] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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47
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Rodriguez JA, Wang X, Hanson JC, Liu G, Iglesias-Juez A, Fernández-Garcı́a M. The behavior of mixed-metal oxides: Structural and electronic properties of Ce1−xCaxO2 and Ce1−xCaxO2−x. J Chem Phys 2003. [DOI: 10.1063/1.1601595] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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48
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Rodriguez JA, Azad S, Wang LQ, Garcı́a J, Etxeberria A, González L. Electronic and chemical properties of mixed-metal oxides: Adsorption and reaction of NO on SrTiO3(100). J Chem Phys 2003. [DOI: 10.1063/1.1539864] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
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49
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Rodriguez JA, Hanson JC, Kim JY, Liu G, Iglesias-Juez A, Fernández-García M. Properties of CeO2and Ce1-xZrxO2Nanoparticles: X-ray Absorption Near-Edge Spectroscopy, Density Functional, and Time-Resolved X-ray Diffraction Studies. J Phys Chem B 2003. [DOI: 10.1021/jp022323i] [Citation(s) in RCA: 183] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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50
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Liu G, Rodriguez JA, Chang Z, Hrbek J, González L. Adsorption of Methanethiol on Stoichiometric and Defective TiO2(110) Surfaces: A Combined Experimental and Theoretical Study. J Phys Chem B 2002. [DOI: 10.1021/jp021155r] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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