In Situ Growth of Fe(Ni)OOH Catalyst on Stainless Steel for Water Oxidation

Abstract Stainless steel contains the elements Fe, Ni, Cr and Mn, which are known as active centers of oxygen evolution reaction (OER) catalysts. The high conductivity of stainless steel also makes it an ideal substrate for OER. These facts imply that stainless steel should be a suitable candidate as an OER electrode. Here, we report a simple solution treatment approach that enables stainless steel to be an efficient and stable OER electrode. It was found that a uniform brown film with highly rippled sheet structure could be in situ grown on stainless steel at room temperature by immersing it in an alkaline oxidant solution containing NaOH and (NH 4 ) 2 S 2 O 8 . The composition of the brown film was found to include Fe(Ni)OOH by Raman and X‐ray photoelectron spectroscopy (XPS) analyses. In 1 M KOH electrolyte, the prepared OER electrode exhibited good electrocatalytic performance with a relatively low overpotential of 300 mV at a benchmark current density of 10 mA/cm 2 and a small Tafel slope of 34 mV/decade. Moreover, this OER electrode showed excellent long‐term stability. This work highlights the possibility of potentially converting accessible materials into useful catalysts through simple chemical treatments.