Stability Investigation on NiFeOx Electrocatalysts for Oxygen Evolution During on and off Cycles in Harsh Alkaline Conditions

Water electrolysis powered by renewable energy sources is a mature and practical technique to produce green hydrogen. Its production cost is heavily influenced by efficiency and durability, with a particular concern being the durability of anodes for oxygen evolution reaction (OER) in highly oxidative and acidic/alkaline environments at elevated temperatures. Durability during intermittent operations with renewable sources, factoring in on/off cycling, is also a consideration. This study investigates the durability of NiFeOx, one of the most active electrocatalysts in alkaline conditions, under various conditions including industrially relevant conditions: 7 M KOH at 80 °C and 600 mA cm−2. The results show that on/off operations with extensive potential variation caused severe degradations compared to constant OER operations. However, stability improves slightly with the addition of saturated Fe3+ ions into the electrolyte, preventing Fe leaching. By dissecting the degradation mechanism step‐by‐step, this study illuminates the limitations and assists in creating strategies for highly durable electrolysis systems.