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Structural defects working as active oxygen-reduction sites in partially oxidized Ta-carbonitride core-shell particles probed by using surface-sensitive conversion-electron-yield x-ray absorption spectroscopy

2010; American Institute of Physics; Volume: 96; Issue: 19 Linguagem: Inglês

10.1063/1.3430543

1520-8842

Hideto Imai, Masashi Matsumoto, Takashi Miyazaki, Shinji Fujieda, Akimitsu Ishihara, Motoko Tamura, Ken-ichiro Ota,

Electrocatalysts for Energy Conversion

We analyzed the local structure of the surface Ta-oxide phase of TaCN/Ta2O5 core-shell particles that have a high oxygen reduction activity by using surface-sensitive conversion-electron-yield x-ray absorption spectroscopy, suppressing the contribution from the TaCN cores. The radial structure analysis revealed that the catalytically-active Ta2O5 phase in the TaCN/Ta2O5 particle surface contains oxygen-vacancy defects with shorter Ta–O bonds leading to the slight expansion of the first Ta–O shell. Such oxygen defects are likely responsible for the oxygen reduction capability by creating electronically favorable oxygen adsorption sites and electron conduction pathways.