A spinel-type high-entropy oxide (Fe0.2Co0.2Ni0.2Mn0.2Zn0.2)3O4 for high efficiency oxygen evolution reaction

The rational design of high-efficiency electrocatalysts with tailored geometric configurations and optimized electronic properties has emerged as a critical strategy for simultaneously accelerating oxygen evolution reaction (OER) kinetics and enhancing catalyst durability in electrochemical water splitting systems. In this work, the application of high-entropy design to spinel oxides effectively integrates the unique spinel structure with refined electronic characteristics inherent in high-entropy metal oxides, endowing the spinel-type high-entropy oxide (Fe 0.2 Co 0.2 Ni 0.2 Mn 0.2 Zn 0.2 ) 3 O 4 -700 with excellent OER performance and stability. The highly dispersed (Fe 0.2 Co 0.2 Ni 0.2 Mn 0.2 Zn 0.2 ) 3 O 4 -700/CC electrode catalyst exhibits remarkable OER performance, with a low overpotential of 313 mV at 10 mA cm −2 and a Tafel slope of 59.7 mV dec −1 , alongside outstanding stability (only 9 mV degradation after 150 h of operation). This OER performance is significantly superior to both monometallic and bimetallic oxides. Structural analyses reveal dynamic surface reconstruction during the OER, resulting in the formation of an amorphous high-entropy oxyhydroxide (FeCoNiMnZnOOH) shell via the co-hydroxylation of the five metallic components. This surface intermediate promotes the formation of O 2 via the lattice oxygen oxidation mechanism. This unique combination of surface adaptability and bulk stability enables both high activity and durability. This research highlights high-entropy spinels as promising OER catalysts, providing both fundamental insights and practical potential for sustainable energy applications.