Engineered Nickel–Iron Nitride Electrocatalyst for Industrial‐Scale Seawater Hydrogen Production

Abstract Seawater electrolysis under alkaline conditions is a crucial technology for sustainable hydrogen production. However, achieving the long‐term stability of the electrocatalyst remains a significant challenge. In this study, it is demonstrated that surface reconstruction of a transition metal nitride (TMN) can be used to develop a highly stable oxygen evolution reaction (OER) electrocatalyst. Rapid introduction of phosphate groups (PO₄³⁻) accelerates the in situ surface reconstruction of Ni₃FeN, generating a catalyst, with a conductive nitride core and Cl⁻‐resistant hydroxide shell that demonstrates outstanding performance, maintaining stability for over 2500 h at 1 A cm⁻² current density in alkaline seawater. In situ characterization and density functional theory (DFT) calculations reveal the dynamic evolution of active sites, providing insights into the mechanisms driving long‐term stability. This work not only introduces an efficient approach to TMN‐based catalyst design but also advances the development of durable electrocatalysts for industrial‐scale seawater hydrogen production.