It is of great significance to develop high-performance bifunctional electrocatalysts for catalyzing two vital reactions in rechargeable zinc-air battery (ZAB). Transitional metal sulfides and N-doped carbon materials are widely reported as effective electrocatalysts of oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), respectively. Herein, an 3D-array-structured catalyst composed of Co_1-xS nanoneedles enwrapped by nitrogen-doped carbon (NC) is in-situ grown on carbon fibre paper substrate. It is revealed that the metastable hexagonal Co_1-xS itself possesses attractive electrocatalytic activities toward both OER and ORR. Additionally, owing to the wrapping-protection effect of polydopamine-derived NC on Co_1-xS, the strong electron coupling between Co_1-xS and NC, and the 3D array structure, Co_1-xS@NC presents excellent OER/ORR catalytic activities and long-term stabilities, superior to Co@NC, Co_1-xS, and NC, and comparable to noble metals and other reported state-of-the-art bifunctional oxygen electrocatalysts. A small energy gap (ΔE) of 0.66 V between the ORR half-wave potential (0.86 V vs RHE) and OER potential (1.52 V vs RHE) at a current density of 10 mA cm⁻², and a diffusion-limit ORR current density of 11.37 mA cm⁻² are achieved. Notably, the flexible ZAB using the catalyst exhibits a markedly higher peak power density of 242 mW cm², and a small charge/discharge voltage gap of ∼ 0.68 V with a high round-trip efficiency of ∼ 64% when cycling at 5 mA/cm².

开发高性能双功能电催化剂对于催化可充电锌空气电池（ZAB）中的两个重要反应具有重要意义。过渡金属硫化物和 N 掺杂的碳材料分别被广泛报道为氧析出反应 (OER) 和氧还原反应 (ORR) 的有效电催化剂。在此，由掺杂氮的碳 (NC) 包裹的 Co _1-x S 纳米针组成的 3D 阵列结构催化剂在碳纤维纸基材上原位生长。结果表明，亚稳态六方 Co _1-x S 本身对 OER 和 ORR 都具有有吸引力的电催化活性。此外，由于聚多巴胺衍生的 NC 对 Co _1-x的包裹保护作用S、Co _1-x S 与NC之间的强电子耦合以及3D 阵列结构，Co _1-x S@NC 表现出优异的OER/ORR 催化活性和长期稳定性，优于Co@NC、Co _{1- x} S 和 NC，可与贵金属和其他报道的最先进的双功能氧电催化剂相媲美。在 10 mA cm ^-2的电流密度下，ORR 半波电位（0.86 V vs RHE）和 OER 电位（1.52 V vs RHE）之间的小能隙 (Δ E ) 为 0.66 V ，以及扩散极限 ORR实现了 11.37 mA cm ^{-2 的}电流密度。值得注意的是，使用该催化剂的柔性 ZAB 表现出明显更高的峰值功率密度，为 242 mW cm ²，以及约 0.68 V 的小充电/放电电压间隙，在以 5 mA/cm ²循环时具有约 64% 的高往返效率。