Functional Interface Optimization Strategy for Fe₃Se₄/NiSe₂ Anchored on MXene for Ultrastable Seawater Splitting at Industrial‐Level Current Density

Abstract Developing efficient and long‐lasting electrocatalysts with industrial‐level current densities for seawater splitting is essential for seawater electrolysis technology to prevent the unwanted chlorine evolution reaction (CER). In this work, an effective technique of constructing functional interactive catalyst interfaces to design bimetallic selenide anchored on 2D MXene (Fe 3 Se 4 /NiSe 2 @MXene) heterostructure catalyst is fabricated on nickel foam. Density‐functional theory (DFT) studies demonstrate that the Fe 3 Se 4 /NiSe 2 @MXene interface modifies the d‐band center and electronic structure of the Ni and Fe sites. The coupling effect from Fe 3 Se 4 /NiSe 2 @MXene heterointerface catalyst enhances the redistribution of charge density and improves the corrosion‐resistant selenide‐rich passivating layers for high seawater splitting activity. The Fe 3 Se 4 /NiSe 2 @MXene catalyst demonstrates exceptional performance in 6 m alkaline natural seawater media, achieving 300 and 360 mV at 500 and 1000 mA cm −2 industrial current densities, respectively, and remained durable for 250 h at 2000 mA cm −2 ultra‐high current density. Remarkably, the Fe 3 Se 4 /NiSe 2 @MXene electrode as a bifunctional electrode in 6 m alkaline natural seawater for seawater splitting achieves robust stability at 500 mA cm −2 for 140 h. This work inspires the optimal design of heterointerface catalysts for industrial seawater electrolysis applications.