In Situ Reconstruction of High‐Entropy Heterostructure Catalysts for Stable Oxygen Evolution Electrocatalysis under Industrial Conditions

Abstract Despite of urgent needs for highly stable and efficient electrochemical water‐splitting devices, it remains extremely challenging to acquire highly stable oxygen evolution reaction (OER) electrocatalysts under harsh industrial conditions. Here, a successful in situ synthesis of FeCoNiMnCr high‐entropy alloy (HEA) and high‐entropy oxide (HEO) heterocatalysts via a Cr‐induced spontaneous reconstruction strategy is reported, and it is demonstrated that they deliver excellent ultrastable OER electrocatalytic performance with a low overpotential of 320 mV at 500 mA cm⁻² and a negligible activity loss after maintaining at 100 mA cm⁻² for 240 h. Remarkably, the heterocatalyst holds outstanding long‐term stability under harsh industrial condition of 6 m KOH and 85 °C at a current density of as high as 500 mA cm⁻² over 500 h. Density functional theory calculations reveal that the formation of the HEA‐HEO heterostructure can provide electroactive sites possessing robust valence states to guarantee long‐term stable OER process, leading to the enhancement of electroactivity. The findings of such highly stable OER heterocatalysts under industrial conditions offer a new perspective for designing and constructing efficient high‐entropy electrocatalysts for practical industrial water splitting.