Stainless Steel Anode for Alkaline Water Electrolysis: Recent Progress in Active and Durable Surface Catalyst Layer Generation

Alkaline water electrolysis (AWE) is a hydrogen manufacturing process that generates "green hydrogen" using electricity derived from renewable energies. Stainless steel (SS), specifically austenitic SS, has recently attracted attention as an anode material for the oxygen evolution reaction (OER) of the AWE. SS anode surfaces are generally activated by generating surface catalyst layers (SCL) for the OER through specific chemical pre-treatment, although the precise chemical compositions and microstructures of the SCL remain under debate. Furthermore, because fluctuations in the electrode potential derived from renewable energies cause remarkable elution of the constituent elements into the electrolyte, corrosion behaviors of the SS anodes should be clarified. This review introduces the recent progress of the SS anodes, particularly in the context of surface treatments to generate surface catalyst layers with high OER performances under simulated AWE conditions. In general, recent reports have clearly shown that surface-treated SS anodes are superior to the commonly employed Ni-based anodes for AWE applications.