Bifunctional CoO/CoS2 hierarchical nanospheres electrocatalyst for rechargeable Zn-Air battery

Limited by sluggish kinetics of oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), exploring low-cost nonprecious materials to replace precious catalysts is urgently desired for the commercialization of efficient rechargeable Zn-air batteries. Herein, a rationally designed oxide/sulfide heterostructures, which named as CoO/CoS2, are successfully realized. Benefited from the electrons interaction between multiple components at the heterojunction interface and the defect structure, the CoO/CoS2 displays highly effective bifunctional catalytic performance and robust durability. CoO/CoS2 expresses a truncated overpotential of 320 mV at 10 mA cm−1 for OER, a half-wave potential of 0.78 V for ORR, and a potential difference of approximately 0.78 V. For practical application, the assembled aqueous Zn-air battery with CoO/CoS2 as the air cathode displays a large open-circuit voltage of 1.40 V, a high power density (84 mW cm−2) and superb charge–discharge stability. This work illustrates the great application prospects of CoO/CoS2 as a next-generation power source device.