Ni3S2/NiFe LDH heterostructure catalysts with a built-in electric field for efficient water electrolysis

Water cracking is a sustainable method for generating hydrogen. However, the high overpotentials during the cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER) pose a significant obstacle to hydrogen production. This paper presents an interface engineering strategy for an efficient dualfunction Ni3S2/NiFe LDH heterostructure electrocatalyst with a built-in electric field. By XPS investigation and DFT calculation, Ni3S2/NiFe LDH heterostructure forms an internal electric field at its interface, changes its electronic structure, and enhances the inherent catalytic efficiency of the catalyst, resulting in a remarkable electrochemical activity and durability in an alkaline environment. In the hydrogen extraction reaction (HER) and oxygen extraction reaction (OER), the corresponding overpotentials are 62 mV and 215 mV, respectively, at current densities of 10 mA cm- 2. Furthermore, this material enables it to work efficiently in alkaline electrolyzers at low cell voltages. It achieves a sustained overall water decomposition at 10 mA cm- 2 for 120 h without degradation. This surpasses the current state-of-the-art combination of 40% Pt/C||RuO2 in terms of performance.