A Universal Saline-Alkaline Etching Procedure to Enhance the Activity of Oxygen Evolution Catalysts

Production of hydrogen from renewables by water electrolysis is a scalable technology that could compete with fossil fuels if the cost of electrolyzer components was lowered. Herein, we demonstrate a simple and fast method for the several-fold enhancement of mass-activity of oxygen evolution catalysts by oxidatively induced etching facilitated by halide ions in alkaline medium. The performance improvements stem from an increase in the density of active sites on the catalyst surface, allowing the activated materials to maintain the same durability as the original ones. This is exemplified by a one-week stability test at 0.5 A cm–2 following 3-fold activation of an initially highly active nickel–iron sulfide catalyst. Critically, the saline-alkaline activation is universal for a wide range of transition-metal-based catalysts including oxides, layered hydroxides, oxyhydroxides, sulfides, selenides, phosphides, and borides. Hence, beyond water electrolysis, this approach may find use in the development of catalysts for a broad range of applications.