Designing a smart heterojunction coupling of cobalt-iron layered double hydroxide on nickel selenide nanosheets for highly efficient overall water splitting kinetics

To design heterojunction electrocatalysts for water splitting in industrial plants, replacing RuO2, IrO2, and Pt/C remains challenging. We prepared heterostructures of nickel selenide (NiSe) and cobalt-iron layer double hydroxide (CoFeLDH), CoFeLDH@NiSe, using hydrothermal and electrodeposition processes. The interfacial coupling enhanced the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER). The CoFeLDH@NiSe required an overpotential of 127 mV and 38 mV for a current density of 10 mA cm−2 with a Tafel slope of 37 mV dec−1 and 33 mV dec−1 for OER and HER in alkaline solutions. Density functional theory calculations showed the enhancement of OER performance. The catalytic activity of CoFeLDH@NiSe increased the electronic conductivity, enhancing the water splitting with 10 mA cm−2 at 1.51 V. The robustness was demonstrated by the long-term stability for 120 h. This study provides a strategy for developing heteronanostructure electrocatalysts for water splitting in fields such as metal-air batteries and energy storage.