Operando Spectroscopic Insight into the Synergistic Catalysis on Dual-hetero-atom Sites in Zinc-air Battery

Abstract The construction and understanding of synergy in well-defined dual-atom active sites is an available avenue for promoting the multistep tandem catalytic reaction. Herein, guiding by the theoretical screening, we construct a dual-hetero-atom catalyst that comprises adjacent Cu-N4 and Se-C3 active sites for high-efficiency Zn-air battery. Device-based operando X-ray absorption spectroscopy coupled with theoretical calculations provide in-depth insights into this dual-atom synergy mechanism during realistic Zn-air battery operation conditions. We demonstrate that foreign-heteroatom Se modulators can efficiently polarize the charge distribution around symmetrical Cu-N4 moieties, and serve as the synergistic site to facilitate the second oxygen reduction step, in which the key OOH*-(Cu1-N4) transforms to O*-(Se1-C2) intermediate on the dual-hetero-atom sites after gaining one electron. As a result, the Se modified dual-hetero-atom catalyst achieves ultrahigh ORR activity with a half-wave potential of 0.905 V vs. RHE and a maximum output power density of 206.5 mW cm-2 in Zn-air battery.