Ni-Cr-Fe-Mo Heterojunction Enables Efficient and Ultra-stable Hybrid Seawater Electrolysis at Industrial Current Densities

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 2 A cm -2 in alkaline and neutral seawater electrolytes, while exhibiting exceptional performance under amperelevel 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 H 2 O cleavage and the other promotes H 2 synthesis. This cooperative process not only optimizes reaction kinetics but also enhances corrosion resistance, 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.