Oxide electrocatalysts band structure

The band structure of oxides is very important for their behavior as electrocatalysts through the role of surface states and chemisorption of intermediates at their surfaces. When a crystalline solid is terminated by a surface, a new set of electronic states appears associated with the surface which are a continuation from the bulk band structure of the solid. These surface states are d-band surface states on transition metal oxides, which play a vital role... 

XAS has been successfully employed in the characterization of a number of catalysts used in low temperature fuel cells. Analysis of the XANES region has enabled determination of the oxidation state of metal atoms in the catalyst or, in the case of Pt, the d band vacancy per atom, while analysis of the EXAFS has proved to be a valuable structural tool. However, the principal advantage of XAS is that it can be used in situ, in a flooded half-cell or true fuel cell environment. While the number of publications has been limited thus far, the increased availability of synchrotron radiation sources, improvements in beam lines brought about by the development of third generation sources, and the development of more readily used analysis software should increase the accessibility of the method. It is hoped that this review will enable the nonexpert to understand both the power and limitations of XAS in characterizing fuel cell electrocatalysts. 

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