Heterogeneous Cr-doped Co3S4/NiMoS4 bifunctional electrocatalyst for efficient overall water splitting

Exploration of efficient and robust catalysts for electrocatalytic water splitting is paramount yet challenging for economical hydrogen production. Here, nanoforest-like heterostructures composed of inner NiMoS₄ nanowires and outer Cr-doped Co₃S₄ nanosheets were grown on nickel foams (Cr–Co₃S₄/NiMoS₄) as highly efficient bifunctional electrocatalysts. As a result, Cr–Co₃S₄/NiMoS₄ heterostructures exhibit low overpotentials of 72 mV and 243 mV for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at 10 mA cm⁻², respectively. Moreover, the water electrolyzer assembled by Cr–Co₃S₄/NiMoS₄ as bifunctional electrodes reaches 10 mA cm⁻² at 1.587 V and maintains exceptional stability over 200 h. The experimental and theoretical characterizations collectively unveil that the charge redistribution occurs at the heterointerface between Cr-doped Co₃S₄ and NiMoS₄, resulting in the regulation of both their electronic structures, which optimizes the adsorption of HER intermediates and decreases the energy barrier of determining step for OER. Additionally, the Cr doping and nanoforest-like morphology increase the intrinsic conductivity and the exposure of active sites, collectively improving the water electrolysis efficiency. This finding presents a promising way to construct and adjust the heterojunction engineering for bifunctional electrocatalysts toward water electrolysis.