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.