Ultrastable Ni─Fe─P‐Based Heterostructures for Seawater Electrolysis

Abstract Seawater electrolysis, powered by renewable energy, presents a promising and sustainable approach to addressing the issues of freshwater shortage and energy crisis. However, the presence of chloride ions (Cl − ) in seawater poses significant challenges, causing severe corrosion and compromising long‐term durability. Unlike conventional strategies that involve coverage of catalysts with protective layers, a reverse design conception is proposed herein to construct a heterostructure with exposed catalyst nanoparticles to simultaneously enhance OER kinetics and reduce Cl − adsorption. The as‐designed electrocatalyst of nickel telluride nanorod arrays decorated with ferronickel phosphide nanoparticles (NiTe/Ni 2 FeP) achieves ultralow overpotential of 232 mV to deliver a current density of 500 mA cm −2 in 1 m KOH & seawater. Furthermore, the electrocatalyst demonstrates high durability, maintaining stable performance for over 6800 h at current densities ranging from 100 to 1000 mA cm −2 under the same condition. Comprehensive characterizations and theoretical calculations reveal that the abundant interfaces between NiTe and Ni 2 FeP create a built‐in electric field effect to enable interfacial charge redistribution, which not only significantly reduces Cl − adsorption to mitigate Cl − induced corrosion, but also facilitates the structure transformation into highly active γ─Ni(Fe)OOH species for enhanced overall activity.