A Current-Adaptive Polyoxovanadates Protected Anode for Efficient and Stable Ampere-Level Seawater Electrolysis.

Abstract

Seawater electrolysis is promising for green hydrogen production, while intensified chloride corrosion at high-current density (HCD) poses significant challenges to the activity and stability of the anodes. Conventional anode catalysts leverage anion electrostatic repulsion to repel chloride but often fail under industrially relevant ampere-level HCD conditions, restricting their applications. Here we report a corrosion-resistant cobalt-vanadium-oxide catalyst featuring in situ formed, current-adaptive polyoxovanadates (POVs) for efficient and stable seawater electrolysis at HCD. As the current densities increase, the vanadate monomers dynamically self-assemble into POVs with significantly increased steric hindrance to Cl^-, thereby enhancing chloride repulsion. The catalyst works stably for over 5000 h at 1000 mA cm^-2 with a low decay rate of 0.83 µV h^- ¹ in seawater electrolyte. Furthermore, the anion exchange membrane seawater electrolyzer only needs 1.64 V at 1000 mA cm^-2 and maintains stable operation for over 1500 h. Technoeconomic analysis results show that H₂ production cost is $1.17/GGE H₂, which surpasses the U.S. Department of Energy's $2.0/GGE H₂ target. This work reports a novel dynamic chloride repulsion behavior at HCD conditions and paves the way for robust corrosion-resistant anode catalysts for seawater electrolysis.