Novel MOF-Derived Nickel Nitride as High-Performance Bifunctional Electrocatalysts for Hydrogen Evolution and Urea Oxidation

Developing bifunctional catalysts toward urea oxidation and hydrogen evolution is a huge challenge. In this study, novel MOF-derived nickel nitride on nickel foam catalysts were successfully synthesized at different temperatures (300, 350, 400 °C) (denoted as C-T, T = 300, 350, 400). C-350 was demonstrated to be a highly active and durable 3D catalyst toward urea oxidation reaction (UOR), with a required potential of 1.337 V at 10 mA/cm². At the same time, C-350 has higher catalytic performance toward hydrogen evolution reaction (HER) than other materials with a low overpotential of 47 mV at 10 mA/cm². Furthermore, its two-electrode alkaline electrolyzer only needs a voltage of 1.503 V to obtain 100 mA/cm², which is 0.160 V lower than that of pure water splitting. Also, the current density can be maintained for at least 24 h, showing its potential for practical applications.