Single-phase ruthenium-based oxide with dual-atoms induced bifunctional catalytic centers enables highly efficient rechargeable Zn-air batteries

Abstract

Composite strategies for constructing dual-atom sites at the hetero-interface provide considerable prospects for designing efficient bifunctional oxygen catalysts. Given the insufficient interface site and the instability of the phase interface, we need to develop more efficient strategies for efficiently utilizing the dual-atom site. Here, we report a doping strategy to construct abundant dual-atom sites in single-phase oxide catalysts. Ru/Mn dual-atom bond formation enables electronic interaction between Ru and Mn, which reduces the oxidation state of Ru sites and meanwhile constructs electron-rich states of Mn sites. DFT calculation was further applied to explore the reaction mechanism. We found that Mn and Ru atoms serve as oxygen reduction and oxygen evolution reaction catalytic sites respectively to facilitate oxygen adsorption and OH* desorption. More importantly, co-adsorption of OOH* on Mn/Ru dual sites can greatly enhance oxygen reduction activity. The resulting Mn-RuO2 catalyst exhibits an ultra-low ORR/OER overpotential of just 0.65 V, substantially lower than RuO2 and MnOx. Remarkably, Mn-RuO2 also demonstrates excellent stability, with minimal ORR decay after repeated OER cycling. Rechargeable zinc-air batteries using Mn-doped RuO2 achieve super-durability for 2000 cycles with a final energy efficiency retention of 87.5 %.