Cobalt Carbide–Nickel\nCarbide Nanosheets Supported\non CoNi Basic Carbonates/Stainless Steel Mesh as a Trifunctional Catalyst\nfor Water Splitting and Zn-Air Batteries

The design of a catalyst applied for electrocatalytic\nwater splitting\nand rechargeable Zn-air batteries (ZABs) is of great significance.\nHerein, we synthesized the stainless steel mesh (SSM)-based Co<sub>2</sub>C-NiC/CoNi basic carbonate (abbreviated as CoNiC/CoNibc/SSM)\nthrough the direct carbonization of CoNibc/SSM. Basic phase characterization\ncertifies that the <i>in situ</i> synthesized ultrathin\nnanosheets on CoNibc/SSM are the complex of CoNiC (a mixture of Co<sub>2</sub>C and NiC). Further electrocatalytic water splitting and rechargeable\nZAB testing confirm that it outperformed the oxygen evolution reaction\n(OER), hydrogen evolution reaction (HER), and oxygen reduction reaction\n(ORR) properties of the pure CoNibc/SSM. The needed overpotential\nof CoNiC/CoNibc/SSM is merely 117.6 mV for HER and 253.4 mV for OER\nwhen the output current density is 10 mA cm<sup>–2</sup>, and\nit delivers a much larger limiting current density (4.51 mA cm<sup>–2</sup>) during the ORR process. In addition, when CoNiC/CoNibc/SSM\nacts as an air cathode of the rechargeable ZAB, the assembled liquid\nbattery can operate over 1600 h long-life cycling, even superior to\nthat assembled with commercial Pt/C + RuO<sub>2</sub>/SSM, while the\nassembled flexible battery exhibits an excellent bendability during\nthe long-life cycling. This work not only achieves an outstanding\nself-powered hydrolysis trifunctional catalyst but also provides a\npractical synthesis guidance to other self-supporting high-active\ncarbon-based materials.