Self-supported NiFe-LDH nanosheets on NiMo-based nanorods as high-performance bifunctional electrocatalysts for overall water splitting at industrial-level current densities

Efficient, durable and economic electrocatalysts are crucial for commercializing water electrolysis technology. Herein, we report an advanced bifunctional electrocatalyst for alkaline water splitting by growing NiFe-layered double hydroxide (NiFe-LDH) nanosheet arrays on the conductive NiMo-based nanorods deposited on Ni foam to form a three-dimensional (3D) architecture, which exhibits exceptional performances for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). In overall water splitting, only the low operation voltages of 1.45/1.61 V are required to reach the current density of 10/500 mA·cm⁻², and the continuous water splitting at an industrial-level current density of 500 mA·cm⁻² shows a negligible degradation (1.8%) of the cell voltage over 1000 h. The outstanding performance is ascribed to the synergism of the HER-active NiMo-based nanorods and the OER-active NiFe-LDH nanosheet arrays of the hybridized 3D architecture. Specifically, the dense NiFe-LDH nanosheet arrays enhance the local pH on cathode by retarding OH⁻ diffusion and enlarge the electrochemically active surface area on anode, while the conductive NiMo-based nanorods on Ni foam much decrease the charge-transfer resistances of both electrodes. This study provides an efficient strategy to explore advanced bifunctional electrocatalysts for overall water splitting by rationally hybridizing HER- and OER-active components.