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Volumn 112, Issue 44, 2008, Pages 17311-17318

Methane dissociation on the ceria (111) surface

Author keywords

[No Author keywords available]

Indexed keywords

ADSORPTION; ANODES; CARBON DIOXIDE; CHEMICAL OXYGEN DEMAND; COKE; COPPER; ELECTRIC BATTERIES; ELECTRODES; FUEL CELLS; METHANE; OXIDATION; SOLID OXIDE FUEL CELLS (SOFC);

EID: 56549095385     PISSN: 19327447     EISSN: 19327455     Source Type: Journal    
DOI: 10.1021/jp8039862     Document Type: Article
Times cited : (62)

References (53)
  • 4
    • 56749087278 scopus 로고    scopus 로고
    • Trovarelli, A, Ed; Imperial College Press: London, UK
    • Catalysis by Ceria and Related Materials; Trovarelli, A., Ed; Imperial College Press: London, UK, 2002; Vol. 2.
    • (2002) Catalysis by Ceria and Related Materials , vol.2
  • 10
    • 52949138328 scopus 로고    scopus 로고
    • Ceria Surfaces and Films for Model Catalytic Studies Using Surface Analysis Techniques
    • Trovarelli, A, Ed, Imperial College Press: London, UK
    • Overbury, S. H.; Mullins, D. R. Ceria Surfaces and Films for Model Catalytic Studies Using Surface Analysis Techniques. In Catalysis by Ceria and Related Materials; Trovarelli, A., Ed.; Imperial College Press: London, UK, 2002; Vol 2, pp 311-341.
    • (2002) Catalysis by Ceria and Related Materials , vol.2 , pp. 311-341
    • Overbury, S.H.1    Mullins, D.R.2
  • 14
    • 0043102601 scopus 로고    scopus 로고
    • Fundamentals and Applications of Ceria in Combustion Reactions
    • Trovarelli, A, Ed; Imperial College Press: London, UK
    • Primet, M.; Garbowski, E. Fundamentals and Applications of Ceria in Combustion Reactions. In Catalysis by Ceria and Related Materials; Trovarelli, A., Ed; Imperial College Press: London, UK, 2002; Vol. 2, pp 407-429.
    • (2002) Catalysis by Ceria and Related Materials , vol.2 , pp. 407-429
    • Primet, M.1    Garbowski, E.2
  • 16
    • 56749113749 scopus 로고    scopus 로고
    • Mogensen, M. Ceria-Based Electrodes. In Catalysis by Ceria and Related Materials; Trovarelli, A., Ed; Imperial College Press: London, UK, 2002; 2, pp 453-481.
    • Mogensen, M. Ceria-Based Electrodes. In Catalysis by Ceria and Related Materials; Trovarelli, A., Ed; Imperial College Press: London, UK, 2002; Vol 2, pp 453-481.
  • 51
    • 56749145438 scopus 로고    scopus 로고
    • In the VASP implementation of DFT+ U, atomic orbitals are used to project the plane-wave Bloch states onto a basis of local cerium 4f states in order to calculate the on-site Coulomb repulsion in the Hubbard contribution to the total energy. One weakness of this projection is that it can lead to a partial occupancy of the cerium 4f states due to overlap of the atomic 4f projectors with the oxygen 2p states in the valence band. This partial occupancy will be penalized by the Hubbard term and, interestingly, ends up favoring reduced ceria. As has been pointed out by Watkins et al.,50 this comes about because Ce3+ has a larger atomic radius than Ce 4, This reduces the overlap between the atomic 4f projectors and the oxygen 2p states in the valence band for Ce3+ and, therefore, lowers the on-site Coulomb repulsion penalty. The reduced CeO2-x state is thus penalized less than the pure CeO2 state by this overlap and is
    • 2 state by this overlap and is consequently stabilized relative to the unreduced state. This stabilization lowers the vacancy creation energy and is the main source of the discrepancy between the two DFT + U approaches.
  • 52
    • 56749140183 scopus 로고    scopus 로고
    • A similar structure is seen in the density of states for the p(2 × 2) unit cell on the (111) surface with one 3fh oxygen vacancy. In this case, two cerium atoms are reduced, creating a linear chain of Ce3+ ions, and, as expected a double peak structure is seen in the density of states. However, a very small gap appears in the middle of the double peak (not shown) which is not seen in the case of hydrogen adsorption. The appearance of this tiny gap is due to the fact that the Ce-Ce bond length alternates along the infinite chain between 4.0 and 3.7 Å in p(2 × 2) unit cell, disrupting the periodicity seen in the p( 1 × 2) unit cell used for hydrogen adsorption. That is, the double peak comes from the tight-binding band along a chain of Ce3+ ions approximately 3.7-4 Å apart, and the gap comes from the fact that the true periodicity is every two Ce3+ ions, or 7.7 Å
    • 3+ ions, or 7.7 Å.
  • 53
    • 56749129484 scopus 로고    scopus 로고
    • 2(g).
    • 2(g).


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.