In Situ Constructed Ni3S2/CoMo2S4 Heterointerface on Nickel Foam for Efficient Bifunctional Water Splitting

Abstract

Developing high-performance bifunctional electrocatalysts for overall water splitting is crucial for sustainable hydrogen production. In this work, a hierarchical Ni3S2/CoMo2S4 heterostructure is engineered in situ on nickel foam (NF) through a simple two-step immersion–hydrothermal sulfidation method. The resulting nanowire-interwoven three-dimensional network provides abundant exposed active sites, large electrochemically active surface area, and efficient charge/mass transport pathways. Strong interfacial electronic coupling between Ni3S2 and CoMo2S4 optimizes optimizes intermediate adsorption and enhances intrinsic catalytic activity toward both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). In alkaline electrolyte, the catalyst delivers low overpotentials of 78 mV at 10 mA cm-2 for HER and 202 mV at 100 mA cm-2 for OER. When configured as both anode and cathode, the electrolyzer requires only 1.68 V to reach 100 mA cm-2 and operates stably for over 12 h. Density functional theory calculations and post-reaction analysis reveal that interfacial synergy promotes charge redistribution and facilitates the formation of catalytically active species. This work demonstrates an efficient noble-metal-free heterostructured electrode with practical potential for cost-effective alkaline water electrolysis.