Abstract:

There has been a long-time desire to replace the costly noble-metal-based catalysts (IrOx, RuOx) and anode material (Ti) with cheap earth-abundant materials, like steels, for acidic water electrolysis. However, traditional stainless steels are considered unstable and non-catalytic in strong acids under high external potential. Here, we report a surface-oxidized Mn-contained stainless steel that possesses significantly improved catalytic current compared with the untreated one, which might be attributed to the mixtures of amorphous and crystalline transition-metal oxides formed on the surface. Simultaneously, the oxidized stainless steel can perform the oxygen evolution reaction (OER) in strong acid for over 20 hours. Near-surface phase transformation caused by Mn depletion might contribute to the extended stability of the surface catalytic layers during operation in acidic solutions and high external potential. This study provides a cost-effective and simple routine to make steel anodes catalytic and stable for water electrolysis in acidic media.