An effective strategy to tune the oxygen vacancy of pyrochlore oxides for electrochemical energy storage and conversion systems

Abstract

Oxygen catalysts that concurrently meet the durability and activity requirements for both the proton exchange membrane water electrolyzer (PEMWE) and the zinc-air battery (ZAB) are rarely reported, despite their tremendous advantages in cost reduction. We use a group of Mg-doped Y2Ru2O7 catalysts for the acidic oxygen evolution reaction (OER), the alkaline OER, and the oxygen reduction reaction, and all demonstrate significantly higher catalytic performance than undoped Y2Ru2O7 and commercial RuO2. The optimal oxygen electrocatalysts, Y1.85Mg0.15Ru2O7, demonstrate great promise in both ZABs and PEMWEs. Our experiments disclose that a hole-doping effect is massively enhanced when the Y3+ in YRO is partially replaced by Mg2+; this promotes oxygen vacancy concentration and multivalence in Ru5+/Ru4+, both of which are closely related to the intrinsic activity of oxygen catalysts. This strategy could be extended to explore other oxygen catalysts with superior efficiency and durability for both PEMWE and ZAB.