Boosting bifunctional electrocatalytic activity in S and N co-doped carbon nanosheets for high-efficiency Zn-air batteries

Zn-air batteries are promising devices for electrochemical energy storage and conversion. Bifunctional oxygen electrocatalysts with low cost are urgently needed to realize practical application. Herein, metal-free porous S and N co-doped carbon nanosheets (SNCs) were prepared through facile two-step thermal treatment. Owing to the synergistic effect of S and N, superior bifunctional electrocatalytic activity toward both oxygen reduction and evolution reactions was achieved, much better than that of singly doped carbon nanosheets. Computations further confirm that the introduction of S into N-doped carbon nanosheets can effectively increase their OER catalytic activity and even the overall catalytic performance. Additionally, Zn-air batteries fabricated with SNCs showed high power density and excellent rechargeability, outperforming most reported metal-free and even metal-based electrocatalysts, and fully demonstrating good prospects for practical application.