Low‐Temperature Exsolution of Cobalt From Perovskite Nanoparticles via Bead Milling for Enhanced Electrocatalytic Oxygen Evolution Reaction

Abstract Although metal exsolution from perovskite materials effectively improves catalytic activity, its high temperature and prolonged operation time present challenges for industrial synthesis efficiency and scalability, emphasizing the necessity for straightforward and scalable fabrication methods at lower temperatures. Herein, a novel catalyst fabrication approach through the bead milling of perovskite nanoparticles are introduced to achieve low‐temperature (300 °C) metal exsolution. The bead milling process reduces the particle size to less than 50 nm and diminishes the degree of crystallinity, thus lowering the exsolution temperature. Consequently, the oxygen evolution reaction (OER) mass activity of Co nanoparticles exsolved from La 0.6 Sr 0.4 CoO 3‐δ perovskites exhibits nearly a sixfold increase compared with pristine materials, demonstrating the enhanced OER activity achieves through bead milling and exsolution processes.