Entropy‐Driven Synthesis of Nanocubic High‐Entropy Perovskite Oxides for Efficient Oxygen Evolution Electrocatalysis

ABSTRACT High‐entropy perovskite oxides (HEPOs) have attracted considerable interest for their promising catalytic properties, yet the controlled synthesis of HEPOs with precisely tailored entropy and well‐defined nanostructures remains a challenge. Herein, we developed a sol–gel approach featuring molecular‐level precursor mixing and controlled calcination to achieve entropy engineering, leading to the formation of HEPOs with well‐defined nanocubic morphology and highly exposed (001) facets. The representative La(MnFeCoNiMo)O 3 demonstrates advanced electrocatalytic performance with low overpotential and high durability for the alkaline oxygen evolution reaction under industrial conditions. Moreover, when integrated into a photovoltaic‐electrolysis system operating under fluctuating power inputs, it demonstrates high adaptability and achieves a notable solar‐to‐hydrogen efficiency of up to 16.1%. Through a combination of in situ and ex situ characterizations, we reveal that the high‐entropy configuration promotes oxygen vacancy formation and enhances metal–oxygen covalency, facilitating reaction kinetics via a lattice oxygen‐mediated pathway. This work provides a scalable entropy‐mediated synthesis route for designing high‐entropy oxides with tailored nanostructures and enhanced catalytic functionalities.