Asymmetrical Ru-O-Mn Bridge Active Sites Fully Decouple Bifunctional Oxygen Electrocatalysis for Rechargeable Zinc-Air Batteries

Abstract

A high-performance bifunctional electrocatalyst toward oxygen evolution/reduction reactions (OER/ORR) is critical for rechargeable zinc-air batteries (ZABs). However, the binding energy scaling of reaction intermediates impedes full optimization of the electrocatalyst, leading to poor bifunctional activity and low efficiency. Here, the OER/ORR cycles are effectively decoupled over a Mn0.3Ru0.7O2 catalyst by asymmetrical “Ru-O-Mn” dual-bridge active sites, with OER intermediates coordinated over the “Ru-O” site and ORR intermediates over the “Mn” site. Due to the metal-oxygen covalency competition between the two sites, lattice oxygen-mediated O-O coupling on the Ru-O site is promoted, whereas the overbinding of *OOH on the Mn site is mitigated to enhance the OER and ORR, respectively, leading to a low ORR-OER potential gap of 0.63 V. The Mn0.3Ru0.7O2-assembled ZAB exhibits a high-power density of 179 mW cm-2 and a long lifespan of over 800 h, outperforming the [Pt/C||RuO2] benchmark. These findings rationalize the design of Ru-O-Mn dual-bridge sites for bifunctional oxygen electrocatalysis and provide a strategy to enhance the ORR/OER bifunctionality for high-performance ZABs.