102
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Nikolla E, Schwank J, Linic S. Measuring and relating the electronic structures of nonmodel supported catalytic materials to their performance. J Am Chem Soc 2009; 131:2747-54. [PMID: 19199629 DOI: 10.1021/ja809291e] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Identifying structure-performance relationships is critical for the discovery and optimization of heterogeneous catalysts. Recent theoretical contributions have led to the development of d-band theory, which relates the calculated electronic structure of a metal to its chemical and catalytic activity. While there are many contributions where quantum-chemical calculations have been utilized to validate the d-band theory, experimental examples relating the electronic structures of commercially relevant nonmodel catalysts to their performance are lacking. We show that even small changes in the near-Fermi-level electronic structures of nonmodel supported catalysts, induced by the formation of surface alloys, can be measured and related to the chemical and catalytic performance of these materials. We demonstrate that critical shifts in the d-band center in alloys are related to the formation of new electronic states in response to alloying rather than to charge redistribution among constitutive alloy elements, i.e., the number of d holes and d electrons localized on the constitutive alloy elements is constant. On the basis of the presented results, we provide a simple, physically transparent framework for predicting shifts in the d-band center in response to alloying and relating these shifts to the chemical characteristics of the alloys.
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Affiliation(s)
- Eranda Nikolla
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136, USA
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103
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Krasheninnikov AV, Lehtinen PO, Foster AS, Pyykkö P, Nieminen RM. Embedding transition-metal atoms in graphene: structure, bonding, and magnetism. PHYSICAL REVIEW LETTERS 2009; 102:126807. [PMID: 19392310 DOI: 10.1103/physrevlett.102.126807] [Citation(s) in RCA: 365] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2009] [Indexed: 05/22/2023]
Abstract
We present a density-functional-theory study of transition-metal atoms (Sc-Zn, Pt, and Au) embedded in single and double vacancies (SV and DV) in a graphene sheet. We show that for most metals, the bonding is strong and the metal-vacancy complexes exhibit interesting magnetic behavior. In particular, an Fe atom on a SV is not magnetic, while the Fe@DV complex has a high magnetic moment. Surprisingly, Au and Cu atoms at SV are magnetic. Both bond strengths and magnetic moments can be understood within a simple local-orbital picture, involving carbon sp(2) hybrids and the metal spd orbitals. We further calculate the barriers for impurity-atom migration, and they agree well with available experimental data. We discuss the experimental realization of such systems in the context of spintronics and nanocatalysis.
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Affiliation(s)
- A V Krasheninnikov
- Laboratory of Physics, Helsinki University of Technology, FI-02015, Finland.
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104
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Gao Y, Wu J, Li Y, Sun P, Zhou H, Yang J, Zhang S, Jin B, Tian Y. A Sulfur-Terminal Zn(II) Complex and Its Two-Photon Microscopy Biological Imaging Application. J Am Chem Soc 2009; 131:5208-13. [DOI: 10.1021/ja808606d] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yuanhao Gao
- Department of Chemistry, Key Laboratory of Inorganic Materials Chemistry of Anhui Province, Anhui University, Hefei 230039, P.R. China, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P.R. China, State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093, P.R. China, and Department of Chemistry, University of Science and Technology of China, Hefei 230026, P.R. China
| | - Jieying Wu
- Department of Chemistry, Key Laboratory of Inorganic Materials Chemistry of Anhui Province, Anhui University, Hefei 230039, P.R. China, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P.R. China, State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093, P.R. China, and Department of Chemistry, University of Science and Technology of China, Hefei 230026, P.R. China
| | - Yiming Li
- Department of Chemistry, Key Laboratory of Inorganic Materials Chemistry of Anhui Province, Anhui University, Hefei 230039, P.R. China, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P.R. China, State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093, P.R. China, and Department of Chemistry, University of Science and Technology of China, Hefei 230026, P.R. China
| | - Pingping Sun
- Department of Chemistry, Key Laboratory of Inorganic Materials Chemistry of Anhui Province, Anhui University, Hefei 230039, P.R. China, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P.R. China, State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093, P.R. China, and Department of Chemistry, University of Science and Technology of China, Hefei 230026, P.R. China
| | - Hongping Zhou
- Department of Chemistry, Key Laboratory of Inorganic Materials Chemistry of Anhui Province, Anhui University, Hefei 230039, P.R. China, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P.R. China, State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093, P.R. China, and Department of Chemistry, University of Science and Technology of China, Hefei 230026, P.R. China
| | - Jiaxiang Yang
- Department of Chemistry, Key Laboratory of Inorganic Materials Chemistry of Anhui Province, Anhui University, Hefei 230039, P.R. China, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P.R. China, State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093, P.R. China, and Department of Chemistry, University of Science and Technology of China, Hefei 230026, P.R. China
| | - Shengyi Zhang
- Department of Chemistry, Key Laboratory of Inorganic Materials Chemistry of Anhui Province, Anhui University, Hefei 230039, P.R. China, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P.R. China, State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093, P.R. China, and Department of Chemistry, University of Science and Technology of China, Hefei 230026, P.R. China
| | - Baokang Jin
- Department of Chemistry, Key Laboratory of Inorganic Materials Chemistry of Anhui Province, Anhui University, Hefei 230039, P.R. China, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P.R. China, State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093, P.R. China, and Department of Chemistry, University of Science and Technology of China, Hefei 230026, P.R. China
| | - Yupeng Tian
- Department of Chemistry, Key Laboratory of Inorganic Materials Chemistry of Anhui Province, Anhui University, Hefei 230039, P.R. China, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P.R. China, State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093, P.R. China, and Department of Chemistry, University of Science and Technology of China, Hefei 230026, P.R. China
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105
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Ching WY, Rulis P. X-ray absorption near edge structure/electron energy loss near edge structure calculation using the supercell orthogonalized linear combination of atomic orbitals method. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:104202. [PMID: 21817422 DOI: 10.1088/0953-8984/21/10/104202] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Over the last eight years, a large number of x-ray absorption near edge structure (XANES) and/or electron energy loss near edge structure (ELNES) spectroscopic calculations for complex oxides and nitrides have been performed using the supercell-OLCAO (orthogonalized linear combination of atomic orbitals) method, obtaining results in very good agreement with experiments. The method takes into account the core-hole effect and includes the dipole matrix elements calculated from ab initio wavefunctions. In this paper, we describe the method in considerable detail, emphasizing the special advantages of this method for large complex systems. Selected results are reviewed and several hitherto unpublished results are also presented. These include the Y K edge of Y ions segregated to the core of a Σ31 grain boundary in alumina, O K edges of water molecules, C K edges in different types of single walled carbon nanotubes, and the Co K edge in the cyanocobalamin (vitamin B(12)) molecule. On the basis of these results, it is argued that the interpretation of specific features of the calculated XANES/ELNES edges is not simple for complex material systems because of the delocalized nature of the conduction band states. The long-standing notion of the 'fingerprinting' technique for spectral interpretation of experimental data is not tenable. A better approach is to fully characterize the structure under study, using either crystalline data or accurate ab initio modeling. Comparison between calculated XANES/ELNES spectra and available measurements enables us to ascertain the validity of the modeled structure. For complex crystals or structures, it is necessary to use the weighted sum of the spectra from structurally nonequivalent sites for comparison with the measured data. Future application of the supercell-OLCAO method to complex biomolecular systems is also discussed.
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Affiliation(s)
- Wai-Yim Ching
- Department of Physics, University of Missouri-Kansas City, Kansas City, MO 64110, USA
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