Self-supported MoS₂/Fe-Ni₃S₂ heterostructures on Ni foam derived from Mo-doped NiFe-LDH for bifunctional HER/OER electrocatalysis

The development of efficient and stable non-noble metal bifunctional electrocatalysts is crucial for water electrolysis as alternatives to noble metal catalysts. Herein, a self-supported MoS₂/Fe-Ni₃S₂ heterostructured electrocatalyst was in situ synthesized on Ni foam (NF) through a facile hydrothermal route followed by solid-phase sulfurization. The as-synthesized catalyst features dense heterointerfaces between MoS₂ and Fe-Ni₃S₂, which trigger remarkable synergistic electrocatalytic effects. Specifically, MoS₂ serves as the dominant active component for the hydrogen evolution reaction (HER), exhibiting optimized hydrogen adsorption, whereas Fe-Ni₃S₂ supplies abundant active sites for the oxygen evolution reaction (OER). Benefiting from the interfacial synergy, accelerated charge transfer and targeted regulation of the adsorption-desorption behaviors of reaction intermediates are realized, thus boosting the reaction kinetics for both HER and OER. Consequently, the MoS₂/Fe-Ni₃S₂ electrode delivers low overpotentials of 89 mV for HER and 139 mV for OER at 10 mA⋅ cm⁻² in alkaline media. When assembled as both cathode and anode in a two-electrode electrolyzer, it affords a current density of 10 mA⋅ cm⁻² at 1.606 V and 300 mA⋅ cm⁻² at 1.925 V respectively, accompanied by outstanding long-term stability. This work provides insight into the rational design of high-performance bifunctional electrocatalysts through heterointerface engineering.