One-Step Synthesis of Heterostructural MoS₂‑(FeNi)₉S₈ on Ni–Fe Foam Synergistically Boosting for Efficient Fresh/Seawater Electrolysis

Seawater is more favorable than freshwater in large-scale hydrogen production by electrolysis as it is considered to be the most plentiful natural resource. However, chloride ions with high concentrations in the electrolyte may easily cause corrosion to electrodes or undesirable side reactions during the implementation of seawater electrolysis, thereby degrading the overall system’s efficiency. Therefore, it is necessary to develop an electrocatalyst with excellent catalytic activity and corrosion resistance in order to achieve high-efficiency seawater electrolysis. In this study, a three-dimensional heterogeneous architecture of (FeNi)₉S₈ nanosheets uniformly decorated with an amorphous MoS₂ layer on Ni-Fe foam (MoS₂-(FeNi)₉S₈/NFF) was successfully prepared via one-step hydrothermal vulcanization. Benefiting from the strong interaction at the heterogeneous interface, effective charge transfer, and the enhanced corrosion resistance by MoS₂-(FeNi)₉S₈ coupling, the self-supported MoS₂-(FeNi)₉S₈/NFF electrocatalyst exhibited superior catalytic activity and stability toward overall fresh/seawater splitting. Moreover, it required a low battery voltage of 1.57 and 1.62 V to reach 50 and 100 mA cm^–2 in an alkaline natural seawater electrolyte, respectively, and possessed impressive durability up to 72 h, exceeding the pair of Pt/C||IrO₂. Accordingly, this study provides a route for the preparation of corrosion-resistant electrocatalysts of hydrogen production by seawater electrolysis.