Redox reaction does not facilitate oxygen evolution on bismuth ruthenate pyrochlore

Abstract

Pyrochlore oxides (A₂B₂O₇) have received great attention as promising candidates for next-generation electrocatalysts because of their superior catalytic activity and high structural stability during the oxygen evolution reaction (OER). However, the catalytic mechanisms of pyrochlore oxides have not been comprehensively revealed yet. Herein, we intensively investigate the redox reactions and changes of local structures of the A- and B-site cations of bismuth ruthenate pyrochlore (Bi₂Ru₂O₇) during the OER by in situ X-ray absorption spectroscopy (XAS) analysis. Particularly, the catalytic activity at bismuth and ruthenium sites could determine the degrees of redox reactions, which compete with oxygen evolution for transferring electrons by the applied potentials during cyclic voltammetry (CV) measurements. Furthermore, we successfully clarify the neighboring atoms of bismuth and ruthenium ions in the first and second coordination shells by Morlet wavelet analysis to reveal the correlation of redox reactions with the consumption of Bi₂Ru₂O₇.