Inducing Electronic Redistribution in High-Entropy Spinel Oxides to Boost Water Oxidation

Abstract To develop anode catalysts for anion-exchange membrane water electrolysis (AEMWE), high performance and long-term durability are essential. Here, we innovatively propose a strategy that integrates high-entropy features into spinel-structured Co3O4 to overcome the typical trade-off between catalyst stability and activity. In the high-entropy spinel (NiMnCuZn)Co2O4, the incorporation of multiple elements induces lattice expansion and electron redistribution, effectively optimizing the electronic structure of active metal sites such as Ni and Co and increasing the proportion of their higher oxidation states. Operando Raman spectra indicate that this promotes the early formation of oxyhydroxide active phases during the oxygen evolution reaction. Consequently, the optimized (NiMnCuZn)Co2O4 exhibits excellent catalytic kinetics, requiring overpotentials of only 225 and 299 mV at 10 and 100 mA cm−2, respectively, outperforming commercial RuO2, and maintaining stable operation for at least 700 h. When integrated into an AEM electrolyzer, it requires only 1.82 V to drive an industrial-scale current density of 1 A cm−2 and operates stably for 500 h. This work establishes fundamental design principles for constructing non-precious metal-based high-entropy spinel oxides as sustainable alkaline OER catalysts.