1
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CO Oxidation over Alumina-Supported Copper Catalysts. Catalysts 2022. [DOI: 10.3390/catal12091030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
CO oxidation, one of the most important chemical reactions, has been commonly studied in both academia and the industry. It is one good probe reaction in the fields of surface science and heterogeneous catalysis, by which we can gain a better understanding and knowledge of the reaction mechanism. Herein, we studied the oxidation state of the Cu species to seek insight into the role of the copper species in the reaction activity. The catalysts were characterized by XRD, N2 adsorption-desorption, X-ray absorption spectroscopy, and temperature-programmed reduction. The obtained results suggested that adding of Fe into the Cu/Al2O3 catalyst can greatly shift the light-off curve of the CO conversion to a much lower temperature, which means the activity was significantly improved by the Fe promoter. From the transient and temperature-programmed reduction experiments, we conclude that oxygen vacancy plays an important role in influencing CO oxidation activity. Adding Fe into the Cu/Al2O3 catalyst can remove part of the oxygen from the Cu species and form more oxygen vacancy. These oxygen vacancy sites are the main active sites for CO oxidation reaction and follow a Mars-van Krevelen-type reaction mechanism.
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A comparison of CO oxidation on cleaned ZnO [Formula: see text] surface and defective ZnO [Formula: see text] surface using density functional theory studies. J Mol Model 2021; 28:12. [PMID: 34936036 DOI: 10.1007/s00894-021-05011-9] [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: 09/13/2021] [Accepted: 12/14/2021] [Indexed: 10/19/2022]
Abstract
In this work, we employed continuously the DFT calculations to study CO oxidation reaction on the defective ZnO [Formula: see text] surface. The oxygen (O) atom was removed from cleaned surface ZnO [Formula: see text] (CS-ZnO) to form the defective ZnO [Formula: see text] surface (DS-ZnO), which contained an O vacancy defect. Hereafter, the formation of oxygen vacancy was found to increase the adsorption abilities of O2 and CO on DS-ZnO, in comparison to those on CS-ZnO. Many steps of elementary reactions including O2 and CO adsorption, reacting between CO and O to form CO2, and CO2 desorption on DS-ZnO were investigated and calculated in terms of the configurations, activation energy, and reaction energy, to which the reaction pathway of CO oxidation has been found. Based on this pathway, the calculation results of the rate controlling step of 0.84 eV corresponding to the exothermic reaction energy of 4.11 eV on DS-ZnO indicated that the CO oxidation on DS-ZnO was more thermodynamically favorable and less kinetically desirable than that on CS-ZnO. In addition, the natural bonds of O2 and CO adsorptions on DS-ZnO were also analyzed by the partial density of state (PDOS) and the electron density difference (EDD) contour plots.
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3
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Jovic V, Consiglio A, Smith KE, Jozwiak C, Bostwick A, Rotenberg E, Di Sante D, Moser S. Momentum for Catalysis: How Surface Reactions Shape the RuO 2 Flat Surface State. ACS Catal 2021. [DOI: 10.1021/acscatal.0c04871] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Vedran Jovic
- Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Institute of Geological and Nuclear Science, Wellington 5012, New Zealand
- School of Chemical Sciences, The University of Auckland, Auckland 1010, New Zealand
| | - Armando Consiglio
- Institut für Theoretische Physik und Astrophysik and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, 97074 Würzburg, Germany
| | - Kevin E. Smith
- Department of Physics, Boston University, Boston, Massachusetts 02215, United States
| | - Chris Jozwiak
- Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Aaron Bostwick
- Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Eli Rotenberg
- Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Domenico Di Sante
- Institut für Theoretische Physik und Astrophysik and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, 97074 Würzburg, Germany
| | - Simon Moser
- Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Physikalisches Institut and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, Würzburg 97074, Germany
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4
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Wu Y, Chen X, Huang D, Zhang L, Ren Y, Tang G, Chen X, Yue B, He H. A study on the acidity of sulfated CuO layers grown by surface reconstruction of Cu 2O with specific exposed facets. Catal Sci Technol 2020. [DOI: 10.1039/d0cy00892c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Surface reconstruction and sulfation improve the acidity of Cu2O, and moderate Lewis acid sites are the active sites in Pechmann condensation.
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Affiliation(s)
- Yanan Wu
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials
- Collaborative Innovation Center of Chemistry for Energy Materials
- Fudan University
- Shanghai 200433
- P. R. China
| | - Xin Chen
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials
- Collaborative Innovation Center of Chemistry for Energy Materials
- Fudan University
- Shanghai 200433
- P. R. China
| | - Daofeng Huang
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials
- Collaborative Innovation Center of Chemistry for Energy Materials
- Fudan University
- Shanghai 200433
- P. R. China
| | - Li Zhang
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials
- Collaborative Innovation Center of Chemistry for Energy Materials
- Fudan University
- Shanghai 200433
- P. R. China
| | - Yuanhang Ren
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials
- Collaborative Innovation Center of Chemistry for Energy Materials
- Fudan University
- Shanghai 200433
- P. R. China
| | - Gangfeng Tang
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials
- Collaborative Innovation Center of Chemistry for Energy Materials
- Fudan University
- Shanghai 200433
- P. R. China
| | - Xueying Chen
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials
- Collaborative Innovation Center of Chemistry for Energy Materials
- Fudan University
- Shanghai 200433
- P. R. China
| | - Bin Yue
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials
- Collaborative Innovation Center of Chemistry for Energy Materials
- Fudan University
- Shanghai 200433
- P. R. China
| | - Heyong He
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials
- Collaborative Innovation Center of Chemistry for Energy Materials
- Fudan University
- Shanghai 200433
- P. R. China
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5
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Yang C, Zhao ZY. Investigation of energy band alignments and interfacial properties of rutile NMO 2/TiO 2 (NM = Ru, Rh, Os, and Ir) by first-principles calculations. Phys Chem Chem Phys 2018; 19:29583-29593. [PMID: 29082994 DOI: 10.1039/c7cp05106a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In the field of photocatalysis, constructing hetero-structures is an efficient strategy to improve quantum efficiency. However, a lattice mismatch often induces unfavorable interfacial states that can act as recombination centers for photo-generated electron-hole pairs. If the hetero-structure's components have the same crystal structure, this disadvantage can be easily avoided. Conversely, in the process of loading a noble metal co-catalyst onto the TiO2 surface, a transition layer of noble metal oxides is often formed between the TiO2 layer and the noble metal layer. In this article, interfacial properties of hetero-structures composed of a noble metal dioxide and TiO2 with a rutile crystal structure have been systematically investigated using first-principles calculations. In particular, the Schottky barrier height, band bending, and energy band alignments are studied to provide evidence for practical applications. In all cases, no interfacial states exist in the forbidden band of TiO2, and the interfacial formation energy is very small. A strong internal electric field generated by interfacial electron transfer leads to an efficient separation of photo-generated carriers and band bending. Because of the differences in the atomic properties of the components, RuO2/TiO2 and OsO2/TiO2 hetero-structures demonstrate band dividing, while RhO2/TiO2 and IrO2/TiO2 hetero-structures have a pseudo-gap near the Fermi energy level. Furthermore, NMO2/TiO2 hetero-structures show upward band bending. Conversely, RuO2/TiO2 and OsO2/TiO2 hetero-structures present a relatively strong infrared light absorption, while RhO2/TiO2 and IrO2/TiO2 hetero-structures show an obvious absorption edge in the visible light region. Overall, considering all aspects of their properties, RuO2/TiO2 and OsO2/TiO2 hetero-structures are more suitable than others for improving the photocatalytic performance of TiO2. These findings will provide useful information for understanding the role and effects of a noble metal dioxide as a transition layer between a noble metal co-catalyst and a TiO2 photocatalyst.
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Affiliation(s)
- Chen Yang
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, P. R. China.
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6
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Synthesis, Characterization and Shape-Dependent Catalytic CO Oxidation Performance of Ruthenium Oxide Nanomaterials: Influence of Polymer Surfactant. APPLIED SCIENCES-BASEL 2015. [DOI: 10.3390/app5030344] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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7
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Cui X, Chen L, Wang Y, Chen H, Zhao W, Li Y, Shi J. Fabrication of Hierarchically Porous RuO2–CuO/Al–ZrO2 Composite as Highly Efficient Catalyst for Ammonia-Selective Catalytic Oxidation. ACS Catal 2014. [DOI: 10.1021/cs500421x] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Xiangzhi Cui
- The
State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese
Academy of Sciences, Shanghai 200050, People’s Republic of China
| | - Lisong Chen
- The
State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese
Academy of Sciences, Shanghai 200050, People’s Republic of China
| | - Yongxia Wang
- The
State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese
Academy of Sciences, Shanghai 200050, People’s Republic of China
| | - Hangrong Chen
- The
State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese
Academy of Sciences, Shanghai 200050, People’s Republic of China
| | - Wenru Zhao
- Key
Laboratory for Ultrafine Materials of Ministry of Education, School
of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237, People’s Republic of China
| | - Yongsheng Li
- Key
Laboratory for Ultrafine Materials of Ministry of Education, School
of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237, People’s Republic of China
| | - Jianlin Shi
- The
State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese
Academy of Sciences, Shanghai 200050, People’s Republic of China
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8
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Permana ADC, Nugroho A, Lee HS, Bak SM, Chung KY, Min BK, Kim J. SYNTHESIS OF HYDROUS RUTHENIUM OXIDE NANOPARTICLES IN SUB- AND SUPERCRITICAL WATER AND THEIR CAPACITIVE PROPERTIES. CHEM ENG COMMUN 2014. [DOI: 10.1080/00986445.2013.805127] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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9
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Wang CC, Wu JY, Pham TLM, Jiang JC. Microkinetic Simulation of Ammonia Oxidation on the RuO2(110) Surface. ACS Catal 2014. [DOI: 10.1021/cs401070n] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Chia-Ching Wang
- Department of Chemical Engineering, National Taiwan University of Science and Technology, 43, Keelung Road, Section 4, Taipei 106, Taiwan
| | - Jyun-Yi Wu
- Department of Chemical Engineering, National Taiwan University of Science and Technology, 43, Keelung Road, Section 4, Taipei 106, Taiwan
| | - Thong L. M. Pham
- Department of Chemical Engineering, National Taiwan University of Science and Technology, 43, Keelung Road, Section 4, Taipei 106, Taiwan
| | - Jyh-Chiang Jiang
- Department of Chemical Engineering, National Taiwan University of Science and Technology, 43, Keelung Road, Section 4, Taipei 106, Taiwan
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10
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Wang H, Schneider WF. Comparative chemistries of CO and NO oxidation over RuO2(110): insights from first-principles thermodynamics and kinetics. MOLECULAR SIMULATION 2012. [DOI: 10.1080/08927022.2012.671521] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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11
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Bao H, Zhang W, Hua Q, Jiang Z, Yang J, Huang W. Crystal-Plane-Controlled Surface Restructuring and Catalytic Performance of Oxide Nanocrystals. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201103698] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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12
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Bao H, Zhang W, Hua Q, Jiang Z, Yang J, Huang W. Crystal-Plane-Controlled Surface Restructuring and Catalytic Performance of Oxide Nanocrystals. Angew Chem Int Ed Engl 2011; 50:12294-8. [DOI: 10.1002/anie.201103698] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Indexed: 11/05/2022]
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13
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Wang H, Schneider WF. Nature and role of surface carbonates and bicarbonates in CO oxidation over RuO2. Phys Chem Chem Phys 2010; 12:6367-74. [DOI: 10.1039/c001683g] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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Wang Y. High Resolution Electron Energy Loss Spectroscopy on Perfect and Defective Oxide Surfaces. ACTA ACUST UNITED AC 2009. [DOI: 10.1524/zpch.2008.6016] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
High resolution electron energy loss spectroscopy (HREELS) is a powerful method for the study of vibrational and electronic excitations at solid surfaces and has been extensively applied to metal single crystal surfaces. As a result of experimental difficulties, unfortunately, much less information is available on adsorbate vibrations at oxide surfaces. This review focuses on recent results showing the successful application of HREELS to study adsorption and reaction of molecules on metal oxide single crystal surfaces. The chemical reactivity of perfect surfaces is first investigated systematically using HREELS combined with thermal desorption spectroscopy (TDS) and low energy electron diffraction (LEED). Furthermore, it is demonstrated that the interaction of adsorbates with surface defects (in particular oxygen vacancies) can also be monitored by vibrational spectroscopy.
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15
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Knop‐Gericke A, Kleimenov E, Hävecker M, Blume R, Teschner D, Zafeiratos S, Schlögl R, Bukhtiyarov VI, Kaichev VV, Prosvirin IP, Nizovskii AI, Bluhm H, Barinov A, Dudin P, Kiskinova M. Chapter 4 X‐Ray Photoelectron Spectroscopy for Investigation of Heterogeneous Catalytic Processes. ADVANCES IN CATALYSIS 2009. [DOI: 10.1016/s0360-0564(08)00004-7] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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16
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Wang H, Schneider WF. Effects of coverage on the structures, energetics, and electronics of oxygen adsorption on RuO2(110). J Chem Phys 2007; 127:064706. [PMID: 17705620 DOI: 10.1063/1.2752501] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Plane-wave supercell DFT calculations within the PW91 generalized gradient approximation are used to examine the influence of oxygen coverage on the structure, energetics, and electronics of the RuO2(110) surface. Filling of O(br) and O(cus) sites is exothermic with respect to molecular O2 at all coverages and causes changes in local Ru electronic structure consistent with the changing metal coordination. By fitting the surface energies of a large number of surface configurations to a two-body interaction model, an O atom is calculated to be bound by 2.55 eV within a filled O(br) row and by 0.98 eV along an otherwise vacant O(cus) row. Lateral interactions modify these binding energies by up to 20%. O(cus)-O(cus) interactions are repulsive and diminish binding energy with increasing O(cus) filling. Due to the favorable relief of local strain, O(br)-O(br) interactions are attractive and favor filling of neighbor br sites. These interaction effects are relatively modest in absolute magnitude but are large enough to influence the ability of the RuO2(110) surface to promote oxidation of relatively weak reductants, such as NO and C2H4.
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Affiliation(s)
- Hangyao Wang
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA
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17
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Jacobi K, Wang Y, Ertl G. Interaction of hydrogen with RuO2(110) surfaces: activity differences between various oxygen species. J Phys Chem B 2007; 110:6115-22. [PMID: 16553424 DOI: 10.1021/jp056341m] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The interaction of hydrogen with RuO(2)(110) surfaces was studied by means of thermal desorption and vibration spectroscopies. The stoichiometric surface exposes two types of coordinatively unsaturated atoms: double-bonded O-bridge and five-fold-bonded Ru-cus, while at the O-rich surface the Ru-cus atoms are covered with single-bonded O-cus. On the stoichiometric RuO(2)(110) surface at 90 K, H(2) either adsorbs molecularly on Ru-cus sites or dissociates and forms with O-bridge an H(2)O-like surface group. If, in addition, also O-cus is present at the surface, hydrogen interacts exclusively with this species forming H(2)O-cus. This demonstrates that hydrogen reacts much more readily with O-cus than with O-bridge as expected from the reduced bond order and smaller binding energy of O-cus. It is furthermore shown that at surface temperatures below 90 K free coordinatively unsaturated Ru-cus sites are needed to activate the incoming H(2) molecules prior to any reaction with O-cus or O-bridge. Generally, Ru-cus sites play a key role for reactions of a number of molecules at the RuO(2)(110) surface. These findings are supported by recent DFT-based calculations but are at variance with other reports.
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Affiliation(s)
- K Jacobi
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany.
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18
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Long-term stability of Ru-based protection layers in extreme ultraviolet lithography: A surface science approach. ACTA ACUST UNITED AC 2007. [DOI: 10.1116/1.2743648] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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19
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Gong XQ, Raval R, Hu P. General insight into CO oxidation: a density functional theory study of the reaction mechanism on platinum oxides. PHYSICAL REVIEW LETTERS 2004; 93:106104. [PMID: 15447424 DOI: 10.1103/physrevlett.93.106104] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2004] [Indexed: 05/24/2023]
Abstract
CO oxidation on PtO2(110) has been studied using density functional theory calculations. Four possible reaction mechanisms were investigated and the most feasible one is the following: (i) the O at the bridge site of PtO2(110) reacts with CO on the coordinatively unsaturated site (CUS) with a negligible barrier; (ii) O2 adsorbs on the bridge site and then interacts with CO on the CUS to form an OO-CO complex; (iii) the bond of O-OCO breaks to produce CO2 with a small barrier (0.01 eV). The CO oxidation mechanisms on metals and metal oxides are rationalized by a simple model: The O-surface bonding determines the reactivity on surfaces; it also determines whether the atomic or molecular mechanism is preferred. The reactivity on metal oxides is further found to be related to the 3rd ionization energy of the metal atom.
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Affiliation(s)
- Xue-Qing Gong
- School of Chemistry, The Queen's University of Belfast, Belfast, BT9 5AG, United Kingdom
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20
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Kim SH, Wintterlin J. Atomic Scale Investigation of the Oxidation of CO on RuO2(110) by Scanning Tunneling Microscopy. J Phys Chem B 2004. [DOI: 10.1021/jp047600v] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sang Hoon Kim
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4−6, D-14195 Berlin, Germany and Ludwig-Maximilians-Universität München, Department Chemie, Butenandtstr. 11, D-81377 München, Germany
| | - J. Wintterlin
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4−6, D-14195 Berlin, Germany and Ludwig-Maximilians-Universität München, Department Chemie, Butenandtstr. 11, D-81377 München, Germany
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21
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Wu X, Selloni A, Nayak SK. First principles study of CO oxidation on TiO2(110): The role of surface oxygen vacancies. J Chem Phys 2004; 120:4512-6. [PMID: 15268619 DOI: 10.1063/1.1636725] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The reactivities of the stoichiometric and partially reduced rutile TiO2(110) surfaces towards oxygen adsorption and carbon monoxide oxidation have been studied by means of periodic density functional theory calculations within the Car-Parrinello approach. O2 adsorption as well as CO oxidation are found to take place only in the presence of surface oxygen vacancies (partially reduced surface). The oxidation of CO by molecularly adsorbed O2 at the O-vacancy site is found to have an activation energy of about 0.4 eV. When the adsorbed O2 is dissociated, the resulting adatoms can oxidize incoming gas-phase CO molecules with no barrier. In all studied cases, once CO is oxidized to form CO2, the resulting surface is defect-free and no catalytic cycle can be established.
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Affiliation(s)
- Xueyuan Wu
- Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180, USA
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22
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Gong XQ, Liu ZP, Raval R, Hu P. A Systematic Study of CO Oxidation on Metals and Metal Oxides: Density Functional Theory Calculations. J Am Chem Soc 2003; 126:8-9. [PMID: 14709033 DOI: 10.1021/ja030392k] [Citation(s) in RCA: 240] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
CO oxidation on Ru(0001), Rh(111), Pd(111), Os(0001), Ir(111), Pt(111), and their corresponding metal oxides is studied using density functional theory. It is found that (i) the reactivity of metal oxide is generally higher than that of the corresponding metal, and (ii) on both metals and metal oxides, the higher the chemisorption energy is in the initial state, the larger the reaction barrier. The barriers are further analyzed by decomposing them into electronic and geometric effects, and the higher reactivity of metal oxides is attributed mainly to the surface geometric effect. Moreover, the electronic effect on both metals and metal oxides follows the same pattern: the shorter the OC-O bond distance in the TS, the higher the barrier.
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Affiliation(s)
- Xue-Qing Gong
- School of Chemistry, The Queen's University of Belfast, Belfast, BT9 5AG, UK
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23
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D’Ajello PCT, Hauser PR, Figueiredo W. Effects of the diffusion of subsurface O atoms on the transient yielding of CO2. J Chem Phys 2003. [DOI: 10.1063/1.1556853] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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24
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Reuter K, Scheffler M. First-principles atomistic thermodynamics for oxidation catalysis: surface phase diagrams and catalytically interesting regions. PHYSICAL REVIEW LETTERS 2003; 90:046103. [PMID: 12570437 DOI: 10.1103/physrevlett.90.046103] [Citation(s) in RCA: 174] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2002] [Indexed: 05/18/2023]
Abstract
Present knowledge of the function of materials is largely based on studies (experimental and theoretical) that are performed at low temperatures and ultralow pressures. However, the majority of everyday applications, like, e.g., catalysis, operate at atmospheric pressures and temperatures at or higher than 300 K. Here we employ ab initio, atomistic thermodynamics to construct a phase diagram of surface structures in the (T,p) space from ultrahigh vacuum to technically relevant pressures and temperatures. We emphasize the value of such phase diagrams as well as the importance of the reaction kinetics that may be crucial, e.g., close to phase boundaries.
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Affiliation(s)
- Karsten Reuter
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
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25
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Liu ZP, Hu P, Alavi A. Catalytic role of gold in gold-based catalysts: a density functional theory study on the CO oxidation on gold. J Am Chem Soc 2002; 124:14770-9. [PMID: 12465990 DOI: 10.1021/ja0205885] [Citation(s) in RCA: 460] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Gold-based catalysts have been of intense interests in recent years, being regarded as a new generation of catalysts due to their unusually high catalytic performance. For example, CO oxidation on Au/TiO(2) has been found to occur at a temperature as low as 200 K. Despite extensive studies in the field, the microscopic mechanism of CO oxidation on Au-based catalysts remains controversial. Aiming to provide insight into the catalytic roles of Au, we have performed extensive density functional theory calculations for the elementary steps in CO oxidation on Au surfaces. O atom adsorption, CO adsorption, O(2) dissociation, and CO oxidation on a series of Au surfaces, including flat surfaces, defects and small clusters, have been investigated in detail. Many transition states involved are located, and the lowest energy pathways are determined. We find the following: (i) the most stable site for O atom on Au is the bridge site of step edge, not a kink site; (ii) O(2) dissociation on Au (O(2)-->2O(ad)) is hindered by high barriers with the lowest barrier being 0.93 eV on a step edge; (iii) CO can react with atomic O with a substantially lower barrier, 0.25 eV, on Au steps where CO can adsorb; (iv) CO can react with molecular O(2) on Au steps with a low barrier of 0.46 eV, which features an unsymmetrical four-center intermediate state (O-O-CO); and (v) O(2) can adsorb on the interface of Au/TiO(2) with a reasonable chemisorption energy. On the basis of our calculations, we suggest that (i) O(2) dissociation on Au surfaces including particles cannot occur at low temperatures; (ii) CO oxidation on Au/inactive-materials occurs on Au steps via a two-step mechanism: CO+O(2)-->CO(2)+O, and CO+O-->CO(2); and (iii) CO oxidation on Au/active-materials also follows the two-step mechanism with reactions occurring at the interface.
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Affiliation(s)
- Zhi-Pan Liu
- Department of Chemistry, University of Cambridge, CB2 1EW, United Kingdom
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Liu ZP, Hu P. A density functional theory study on the active center of Fe-only hydrogenase: characterization and electronic structure of the redox states. J Am Chem Soc 2002; 124:5175-82. [PMID: 11982382 DOI: 10.1021/ja0118690] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have carried out extensive density functional theory (DFT) calculations for possible redox states of the active center in Fe-only hydrogenases. The active center is modeled by [(H(CH(3))S)(CO)(CN(-))Fe(p)(mu-DTN)(mu-CO)Fe(d)(CO)(CN(-))(L)](z)() (z is the net charge in the complex; Fe(p)= the proximal Fe, Fe(d) = the distal Fe, DTN = (-SCH(2)NHCH(2)S-), L is the ligand that bonds with the Fe(d) at the trans position to the bridging CO). Structures of possible redox states are optimized, and CO stretching frequencies are calculated. By a detailed comparison of all the calculated structures and the vibrational frequencies with the available experimental data, we find that (i) the fully oxidized, inactive state is an Fe(II)-Fe(II) state with a hydroxyl (OH(-)) group bonded at the Fe(d), (ii) the oxidized, active state is an Fe(II)-Fe(I) complex which is consistent with the assignment of Cao and Hall (J. Am. Chem. Soc. 2001, 123, 3734), and (iii) the fully reduced state is a mixture with the major component being a protonated Fe(I)-Fe(I) complex and the other component being its self-arranged form, Fe(II)-Fe(II) hydride. Our calculations also show that the exogenous CO can strongly bond with the Fe(II)-Fe(I) species, but cannot bond with the Fe(I)-Fe(I) complex. This result is consistent with experiments that CO tends to inhibit the oxidized, active state, but not the fully reduced state. The electronic structures of all the redox states have been analyzed. It is found that a frontier orbital which is a mixing state between the e(g) of Fe and the 2 pi of the bridging CO plays a key role concerning the reactivity of Fe-only hydrogenases: (i) it is unoccupied in the fully oxidized, inactive state, half-occupied in the oxidized, active state, and fully occupied in the fully reduced state; (ii) the e(g)-2 pi orbital is a bonding state, and this is the key reason for stability of the low oxidation states, such as Fe(I)-Fe(I) complexes; and (iii) in the e(g)-2 pi orbital more charge accumulates between the bridging CO and the Fe(d) than between the bridging CO and the Fe(p), and the occupation increase in this orbital will enhance the bonding between the bridging CO and the Fe(d), leading to the bridging-CO shift toward the Fe(d).
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Affiliation(s)
- Zhi-Pan Liu
- School of Chemistry, The Queen's University of Belfast, Belfast, BT9 5AG, UK
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Liu ZP, Hu P. An insight into alkali promotion: a density functional theory study of CO dissociation on K/Rh(111). J Am Chem Soc 2001; 123:12596-604. [PMID: 11741424 DOI: 10.1021/ja011446y] [Citation(s) in RCA: 127] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The important role of alkali additives in heterogeneous catalysis is, to a large extent, related to the high promotion effect they have on many fundamental reactions. The wide application of alkali additives in industry does not, however, reflect a thorough understanding of the mechanism of their promotional abilities. To investigate the physical origin of the alkali promotion effect, we have studied CO dissociation on clean Rh(111) and K-covered Rh(111) surfaces using density functional theory. By varying the position of potassium atoms relative to a dissociating CO, we have mapped out the importance of different K effects on the CO dissociation reactions. The K-induced changes in the reaction pathways and reaction barriers have been determined; in particular, a large reduction of the CO dissociation barrier has been identified. A thorough analysis of this promotion effect allows us to rationalize both the electronic and the geometrical factors that govern alkali promotion effect: (i) The extent of barrier reductions depends strongly on how close K is to the dissociating CO. (ii) Direct K-O bonding that is in a very short range plays a crucial role in reducing the barrier. (iii) K can have a rather long-range effect on the TS structure, which could reduce slightly the barriers.
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Affiliation(s)
- Z P Liu
- School of Chemistry, The Queen's University of Belfast, Belfast BT9 5AG, UK
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Over H, Seitsonen AP, Lundgren E, Schmid M, Varga P. Direct imaging of catalytically important processes in the oxidation of CO over RuO2(110). J Am Chem Soc 2001; 123:11807-8. [PMID: 11716742 DOI: 10.1021/ja016408t] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- H Over
- Fritz-Haber Institut der MPG, Faradayweg 4-6, D-14195 Berlin, Germany.
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