In Situ Synthesis of High-Entropy (Oxy)Hydroxides Via Electrochemical Reconfiguration As Catalysts For Efficient Water Oxidation.

Surface reconstruction plays a pivotal role in enhancing the activity of the oxygen evolution reaction (OER), particularly in terms of the structural transformation from metal oxides to (oxy)hydroxides. Herein, a novel (oxy)hydroxide (FeCoNiCuMoOOH) with high entropy is developed by the electrochemical reconstitution of corresponding oxide (FeCoNiCuMoO x ). Significantly, the FeCoNiCuMoOOH exhibits much higher OER electrocatalytic activity and durability with an overpotential as low as 201 mV at a current density of 10 mA cm -2 , and with a Tafel slope of 39.4 mV dec -1 . The FeCoNiCuMoOOH/NF presents high stability when testing under a constant current at 100 mA cm -2 within 1000 h. The surface reconstruction is a process of dissolution-reprecipitation of Cu and Mo species and co-hydroxylation of five metal species, which ultimately leads to the formation of FeCoNiCuMoOOH from FeCoNiCuMoOx. This study holds great significance in the realm of designing high-entropy (oxy)hydroxides catalysts with exceptional activity and stability for OER.