A corrosion-resistant and OER active stainless steel anode for water splitting in acidic Media

The development of cost-effective and durable anode materials is crucial for advancing proton exchange membrane (PEM) water electrolysis. In this study, we demonstrate a simple thermal oxidation approach to activate a manganese-cobalt-containing stainless steel for the oxygen evolution reaction (OER) in 0.1 M HClO 4 . The surface-modified stainless steel exhibits a low overpotential of 440 mV at 10 mA/cm 2 while maintaining a faradaic efficiency of 99.9%. Long-term chronopotentiometry at 10 mA/cm 2 confirms stable operation for over 100 hours without significant degradation. Comparative structural analysis on the stainless steel without Co reveals that the enhanced performance originates from a dual-layer structure composed of crystalline α-Mn 2 O 3 nanoparticles and a Co-rich interfacial layer. The α-Mn 2 O 3 phase provides abundant catalytically active Mn 3+ sites, while the Co-rich layer maintains structural integrity and electron conductivity by strongly bridging the oxide surface to the matrix. By leveraging mature steel-manufacturing processes, this work presents a scalable and low-cost strategy to fabricate non-noble-metal steel anodes through a simple one-step heat treatment process, highlighting a promising pathway toward more affordable green hydrogen production. • Stainless steel shows both catalytic activity and stability for water splitting in acidic media. • Mn-based secondary passivation prevents corrosion of the matrix above water splitting potential. • Thermally formed Mn oxides on the surface provides enhanced OER activity. • Co-rich grains with low corrosion kinetics in surface structure ensures high OER stability.