Self-supported NiFe-LDH@CoSx nanosheet arrays grown on nickel foam as efficient bifunctional electrocatalysts for overall water splitting

Electrocatalytical water splitting to produce hydrogen energy is a promising green technology to solve energy crisis and environmental issues. The development of highly efficient and low-cost electrocatalysts is crucial for mass hydrogen production from water splitting. We newly assemble the self-standing 3D NiFe-LDH@CoSx/NF bifunctional electrocatalysts, via the electrodeposition of amorphous CoSx on two-dimensional (2D) NiFe-LDH nanosheets which are supported by porous nickel foam (NF). The integration of HER-active electrocatalyst of CoSx with outstanding OER catalyst of NiFe-LDH guarantees the bifunctional electrocatalytic activity. Furthermore, the formation of the constructed interfaces between amorphous CoSx and NiFe-LDH nanosheets synergistically favors the electron transfer. Therefore, this novel NiFe-LDH@CoSx/NF hierarchical assembly needs ultralow overpotentials of 136 mV (for HER) and 206 mV (for OER) to afford the 10 mA cm−2 current density in alkaline medium (1 M KOH). An electrolyzer based on the NiFe-LDH@CoSx/NF produces an extremely low cell voltage (1.537 V) and good durability. This study offers a promising strategy for facile fabrication of low-cost electrocatalysts which boost the electrocatalytic performance for overall water splitting.