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

The design of a catalyst applied for electrocatalytic water splitting and rechargeable Zn-air batteries (ZABs) is of great significance. Herein, we synthesized the stainless steel mesh (SSM)-based Co2C-NiC/CoNi basic carbonate (abbreviated as CoNiC/CoNibc/SSM) through the direct carbonization of CoNibc/SSM. Basic phase characterization certifies that the in situ synthesized ultrathin nanosheets on CoNibc/SSM are the complex of CoNiC (a mixture of Co2C and NiC). Further electrocatalytic water splitting and rechargeable ZAB testing confirm that it outperformed the oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and oxygen reduction reaction (ORR) properties of the pure CoNibc/SSM. The needed overpotential of CoNiC/CoNibc/SSM is merely 117.6 mV for HER and 253.4 mV for OER when the output current density is 10 mA cm–2, and it delivers a much larger limiting current density (4.51 mA cm–2) during the ORR process. In addition, when CoNiC/CoNibc/SSM acts as an air cathode of the rechargeable ZAB, the assembled liquid battery can operate over 1600 h long-life cycling, even superior to that assembled with commercial Pt/C + RuO2/SSM, while the assembled flexible battery exhibits an excellent bendability during the long-life cycling. This work not only achieves an outstanding self-powered hydrolysis trifunctional catalyst but also provides a practical synthesis guidance to other self-supporting high-active carbon-based materials.