Interface-Engineered NiSe₂/Ni-Fe₂P Nanocubes for Efficient and Durable Seawater Electrolysis

Seawater electrolysis technology holds significant potential for efficient utilization of abundant seawater resources. However, its practical application is constrained by impurity interference in seawater and chlorine gas evolution during the oxygen evolution reaction (OER). To address these challenges, we employed a self-sacrificial template strategy using NiSe₂/NF as the sacrificial template. The etching effect of K₃[Fe(CN)₆] induced interfacial reactions to in situ synthesize NiSe₂@NiFe-PBA nanoboxes, which were subsequently transformed into nanocube spherical morphologies (NiSe₂/Ni-Fe₂P) through vapor-phase phosphidation. The NiSe₂/Ni-Fe₂P catalyst demonstrates an excellent OER performance in alkaline seawater, requiring an ultralow overpotential of 281 mV to achieve 100 mA cm^-2, coupled with a remarkable stability exceeding 100 h. When integrated into a full water-splitting system, the electrolyzer delivers 100 mA cm^-2 at only 1.854 V, maintaining stability for over 200 h. Comprehensive evaluation of the hydrogen evolution reaction (HER) performance across all samples revealed that the NiSe₂@NiFe-PBA/NF catalyst achieved a current density of -10 mA cm^-2 at an overpotential of 168 mV in 1.0 M KOH electrolyte. Further DFT calculations demonstrated that compared to pure-phase NiSe₂, the NiSe₂@NiFe-PBA heterostructure effectively modulated surface hydrogen adsorption energy and reduced the HER reaction barrier, thereby significantly enhancing the catalytic activity.