One‐Step in Situ Etching Unlocks the OER Potential of Stainless Steel

The growing demand for sustainable energy solutions has driven the search for high‐performance electrocatalysts for the oxygen evolution reaction (OER). While nickel‐iron (Ni‐Fe) compounds show promise, their synthesis often involves complex methods and binder‐dependent electrode fabrication. This study presents a facile one‐step in situ hydrothermal etching strategy to transform commercially available 316L stainless steel felt (SSF) into a high‐performance OER electrode. By employing a corrosive solution of sodium periodate and sodium hydroxide, metallic Ni and Fe in SSF are selectively converted into catalytically active NiFe 2 O 4 nanoparticles, whereas non‐catalytic chromium is removed. The resulting electrode exhibits exceptional OER activity, achieving low overpotentials of 207 and 270 mV at 10 and 100 mA cm −2 , respectively, a small Tafel slope of 42.5 mV dec −1 , and remarkable long‐term stability. This cost‐effective approach (∼$0.084 cm −2 ) leverages the inherent composition of stainless steel, eliminates the need for binders and offers a scalable route to durable electrocatalysts.