High Configuration Entropy Activated Lattice Oxygen for O₂ Formation on Perovskite Electrocatalyst

The single-phase oxides with elemental complexity and compositional diversity, usually named high entropy oxides, feature homogeneously dispersed multi-metallic elements in equiatomic concentration. The unusual properties of high entropy oxides endow their potential application in clean-energy-related electrocatalysis. However, the possible fundamental relationship between configuration entropy and the underlying catalytic mechanism is still not well understood and established. Herein, a high entropy perovskite cobaltate consisting of five equimolar metals in the B-site (Mg, Mn, Fe, Co, and Ni) is employed as an electrocatalyst for oxygen evolution reaction (OER). The configuration entropy serves as an effective tool to promote the intrinsic activity of the Co reactive site and manipulate the OER mechanism. The high entropy cobaltate demonstrates a lower overpotential of 320 mV at a current density of 10 mA cm⁻², outperforming other counterparts. The X-ray spectroscopies disclose the synergistic charge-exchange effect among different cations and the formation of a new oxygen hole state. Combinatorially computational and experimental results unveil the enigma that the high configuration entropy leads to the random occupation of cations, facilitates the surface reconstruction, and benefits the formation of stable surface oxygen vacancies. Owing to these merits, the O₂ formation is found to be kinetically favorable via the lattice oxygen mechanism.