Influence of Surface Oxygen Vacancies and Ruthenium Valence State on the Catalysis of Pyrochlore Oxides.

Proton exchange membrane (PEM) water electrolysis is a promising energy storage solution by electrochemically splitting water into hydrogen fuel and oxygen. However, the sluggish kinetics, high operating potential, and corrosive acidic environment during the oxygen evolution reaction (OER) require the use of scarce and costly Ir-based oxides, tremendously hampering its large-scale commercialization. Hence, developing active and stable anode catalysts with reduced precious-metal usage is desperately essential. For the first time, we report a group of YBaRuO pyrochlore oxides and employ them in acid OER and PEM electrolyzers. We reveal the mechanism for the promoted OER performance of Ba-doped YRuO in which partially replacing Y by Ba in YRuO greatly facilitates the hole-doping effect, which generates massive oxygen vacancy and multivalence of Ru/Ru, thus boosting the OER performance of YBaRuO. This work provides an effective method and paradigm for improving the electrocatalytic property of pyrochlore oxides.