Engineering N─TM(Co/Fe)─P Interfacial Electron Bridge in Transition Metal Phosphide/Nitride Heterostructure Nanoarray for Highly Active and Durable Hydrogen Evolution in Large‐Current Seawater Electrolysis

Abstract Hydrogen production via alkaline seawater electrolysis represents a promising strategy for future sustainable energy development. In this study, a FeCoP/TiN/CP(carbon paper) nanoarray electrode with exceptional hydrogen evolution reaction (HER) activity and durability at the industrial current density is successfully fabricated by engineering electronic coupling at the N─transition metal (TM, Co/Fe)─P interfacial bridge. Remarkably, the FeCoP/TiN/CP electrode requires only an overpotential of 129 mV (alkaline fresh water) and 152 mV (alkaline seawater) to achieve a current density of 500 mA cm −2 , and stable operation is demonstrated for 2000 h in alkaline freshwater and 340 h in alkaline seawater at 500 mA cm −2 with negligible degradation. The superior HER performance stems from the unique nanoarray architecture and the phase interface N─TM(Co/Fe)─P bridge bonding, which enhances wettability, facilitates bubble release, and provides resistance to seawater corrosion. Theoretical calculations demonstrate that the interfacial N─TM(Co/Fe)─P bridging regulates the electronic structure of FeCoP, promoting water adsorption and dissociation, while optimizing the intermediate H* free energy. Furthermore, the covalent nature of the N‐TM(Co/Fe)‐P bridging, along with the strengthened Co/Fe‐P bonds, contributes to the superior stability of FeCoP/TiN/CP. This study not only provides new insights into the design of highly active heterostructure electrocatalysts, but also paves the new way for the practical and cost‐effective hydrogen production from seawater electrolysis.