Facile synthesis and efficient electrochemical water splitting of bifunctional nanostructured Ni-based layered double hydroxide/sulfide composite

The development of efficient, stable and low-cost bifunctional electrocatalyst for water splitting is of great practical significance for the industrial application of hydrogen production. In this paper, a well-aligned columnar nickel sulfide and NiAl layered double hydroxides composite (NiAl-LDH/Ni3S2) supported on Ni-foam substrate was successfully designed and prepared by successive hydrothermal processes. Ni3S2 nanorod arrays attached to Ni-foam could provide large open space and short ions diffusion path, and NiAl-LDH provides large contact area with electrolyte, thus enabling fast and reversible redox process, which together could promote electrocatalytic activity. Accordingly, the NiAl-LDH/Ni3S2/NF electrode shows excellent HER and OER performance, in which the low overpotentials of 53.6, 90.2 and 209.2 mV are needed to drive the current density of 10, 20 and 100 mA/cm2 for HER, and similarly for OER, it needs 350.4 mV low overvoltage to reach 100 mA/cm2. In the self-assembled device, the overall water splitting reaction can be driven at a cell voltage of 1.56 V when NiAl-LDH/Ni3S2/NF electrode used as cathode and anode, to achieve the current density of 10 mA/cm2, and the loss voltage is only 16.5 mV within 10 h, showing the excellent stability. The well-constructed NiAl-LDH/Ni3S2/NF is a promising material in the area of electrocatalytic water splitting, which is of practical significance to realize the industrial development of hydrogen production.