In-situ evolution of active layers on commercial stainless steel for stable water splitting

Efforts to explore earth-abundant, non-precious electrocatalyst, especially commercial stainless steel, to replace precious-metal-based catalyst have attracted increasing interest in renewable energy research. Herein, we design a facile and simple route to fabricate highly efficient 316L-type stainless steel-based electrocatalysts for water splitting by CH₄ plasma. After CH₄ plasma treatment, the amorphous carbon layer and the graphene encapsulated Fe₃C nanoparticles are observed on the surface of stainless steel, which play the roles of active sites and protective layer for simultaneously providing an acceptable hydrogen evolution reaction (HER) and excellent oxygen evolution reaction (OER). The optimized stainless steel-based electrocatalyst exhibits an overpotential of only 290 mV at 10 mA cm⁻² and possesses outstanding kinetics (the Tafel slope of 38 mV dec^-1) for OER in the 1.0 M KOH aqueous solution. We anticipate that the operating strategy of our system may aid the development of commercial non-precious productions as the efficient electrocatalysts for energy storage and conversion.