Enhancing electrocatalytic performance for rechargeable Zn-air battery through interface engineering and dual-doping strategy

In this study, we report on the preparation of uniform hollow-structured nanosphere which has abundant N, S co-doped CNT encapsulating heterostructured Co/CoS2 nanoparticles (Co/CoS2/NSCNT). The bifunctional electrocatalytic performance of these materials for ORR and OER is significantly enhanced by the synergistic effect of strongly coupled heterojunctions in the Co/CoS2 nanoparticles and abundant heteroatom dopants in the CNT shells. The Co/CoS2/NSCNT exhibits half-wave potential of 0.890 V vs. RHE and overpotential of 359 mV at 10 mA cm−2 for ORR and OER, respectively. Moreover, rechargeable ZAB assembled with the Co/CoS2/NSCNT catalyst delivers a specific capacity of 746 mAh gZn−1 and a peak power density of 156.8 mW cm−2, which exceed those values of precious metal-based ZAB (673 mAh gZn−1 and 136.9 mW cm−2, respectively). Additionally, the heteroatom-doped CNT shell prevents the dissolution and aggregation of transition metal-based active species during the electrochemical reaction in alkaline condition, thereby contributing excellent long-term cyclability of rechargeable ZAB. These findings demonstrate the potential of Co/CoS2/NSCNTs as high-performance electrocatalysts for rechargeable ZABs, and provide insights into the design of efficient and cost-effective electrocatalysts for energy storage applications.