Engineering B‐Site Configurational Entropy in Perovskite Oxides for Enhanced Alkaline Oxygen Evolution Reaction

High-entropy composition design offers an effective approach to overcome the sluggish oxygen evolution reaction (OER) kinetics of lanthanum-based perovskite oxides. By incorporating a wider variety of metal cations into the B-site sublattice, the configurational entropy increases accordingly. Following this high-entropy compositional strategy, low-entropy LaCoO₃, medium-entropy La(FeCoNi)O₃, and high-entropy La(MnFeCoNiCu)O₃ were successfully synthesized via a facile sol-gel combustion method. The construction of the high-entropy perovskite oxide (HEPO) was found to substantially alter the morphology, crystal structure, and electronic environment, leading to reduced particle size, modulated B-site metal valence states, and enriched oxygen vacancies. These modifications collectively induce synergistic effects among multiple B-site metal active sites and promote the participation of lattice oxygen through the introduction of surface oxygen defects, thereby activating the oxygen-mediated (LOM) pathway of OER. Remarkably, the as-prepared HEPO exhibited superior OER performance in alkaline media, achieving a low overpotential of 303 mV at 10 mA cm^-2, a small Tafel slope of 43 mV dec^-1, and excellent stability over 100 h of continuous operation. This work provides valuable insights into the role of B-site configurational entropy in perovskite oxides and highlights the potential of high-entropy design strategies for developing advanced OER electrocatalysts.