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

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, Y_1.85Mg_0.15Ru₂O₇, 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.