Ni–Cr–Fe–Mo heterojunction enables efficient and ultra-stable hybrid seawater electrolysis at industrial current densities

Abstract

Direct seawater electrolysis represents a pivotal technology for green hydrogen production. However, achieving efficient and stable cathodic heterostructures capable of maintaining long-term stability under industrial current densities remains a significant challenge. This work reports an in situ constructed Ni–Cr–Fe–Mo heterostructure derived from four transition metal powders, which feature multilevel catalytic heterointerfaces and abundant multifunctional active sites. The heterostructure demonstrates sustained hydrogen evolution for 50 hours at 2000 mA cm⁻² in alkaline and neutral seawater electrolytes, while exhibiting exceptional performance under ampere-level current densities. Density functional theory (DFT) calculations reveal that two distinct active sites at the multiscale Ni–Cr–Fe–Mo heterointerfaces synergistically accelerate the hydrogen evolution reaction (HER) through a relay catalysis mechanism: one site facilitates H₂O cleavage and the other promotes H₂ synthesis. This cooperative process not only optimizes reaction kinetics but also enhances the long-term stability, enabling persistent high-efficiency seawater electrolysis. The study provides fundamental insights into the mechanisms driving long-term operational stability and offers a novel paradigm for developing durable heterostructures for industrial-scale seawater hydrogen production.