The dynamic anti-corrosion of self-derived space charge layer enabling long-term stable seawater oxidation

Developing corrosion-resistant oxygen evolution electrocatalysts that can sustain seawater electrolysis is crucial but challenging for hydrogen production. Herein, we develop a bimetallic oxyhydroxide electrocatalyst with self-derived selenate space charge layer (SeO42− SCL) by in-situ electrochemically reconstructing cobalt-doped nickel diselenide (Co-NiSe2) pre-catalyst, enabling long-term stability for seawater electrolysis. In-situ experiments and theoretical results reveal the promoting effect of cobalt-doping on the reconstruction of NiSe2 and generation of dynamically stable oxygen vacancy sites. Importantly, the SeO42− SCL derived from the reconstruction process shows a dynamic anti-corrosion behavior, thus protecting metal species from dissolution and meanwhile without blocking the diffusion and adsorption of reactive species. Consequently, a two-electrode cell assembled by this Co-NiSe2 pre-catalyst as an anode, reaches an industrial current density (500 mA cm−2) at a cell voltage of 1.70 V, and that works stably for over 1500 h in alkaline seawater, which is of significance for promoting the practicality of low-cost catalysts.