Exceptional scaling relation exhibited by oxygen reduction reaction intermediates on TiO2 surfaces
ORAL
Abstract
Enhancing the oxygen reduction reaction (ORR) is a major topic of electrocatalysis, and surfaces have long been designed to realize a full alignment of the adsorption energies of the reaction intermediates, O2*, O*, OH* and OOH*. The alignment is not easy to realize because the adsorption energies often change obeying a linear relationship among them, known as the scaling relation, rather than change independently by modifying the surface. Pristine oxide surfaces tend to show the scaling relation [1], but defective TiO2, attracted attention as the electrocatalyst beyond Pt, may behave exceptionally because of the measured high reactivity.
Our density functional calculations have shown that OH* and OOH* on defective TiO2 surfaces follow the same scaling relation found for typical pristine oxide surfaces, suggesting defective TiO2 is not closer to the ideal catalyst. To our surprise, however, there are metastable surfaces whose pristine surfaces exhibit a significantly deviated relation. This exceptional behavior is related to the fact that those surfaces let OOH* dissociate into O* at a two-folded O site and OH* at a Ti. The deviation from the scaling relation suggests a possibility towards realizing an ideal catalyst.
[1] I. C. Man et al., ChemCatChem 3, 1159(2011).
Our density functional calculations have shown that OH* and OOH* on defective TiO2 surfaces follow the same scaling relation found for typical pristine oxide surfaces, suggesting defective TiO2 is not closer to the ideal catalyst. To our surprise, however, there are metastable surfaces whose pristine surfaces exhibit a significantly deviated relation. This exceptional behavior is related to the fact that those surfaces let OOH* dissociate into O* at a two-folded O site and OH* at a Ti. The deviation from the scaling relation suggests a possibility towards realizing an ideal catalyst.
[1] I. C. Man et al., ChemCatChem 3, 1159(2011).
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Presenters
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Yoshiyuki Yamamoto
Institute for Solid State Physics, The University of Tokyo, The Institute for Solid State Physics, The University of Tokyo
Authors
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Yoshiyuki Yamamoto
Institute for Solid State Physics, The University of Tokyo, The Institute for Solid State Physics, The University of Tokyo
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Shusuke Kasamatsu
Institute for Solid State Physics, The University of Tokyo, Univ of Tokyo-Kashiwanoha, The Institute for Solid State Physics, The University of Tokyo
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Osamu Sugino
Institute for Solid State Physics, The University of Tokyo, Institute of Solid State Physics, University of Tokyo, Univ of Tokyo-Kashiwanoha, The Institute for Solid State Physics, The University of Tokyo