Lanthanum‐Induced MnO ₂ /Mn ₂ O ₃ Dual‐Phase Heterostructure for Efficient and Stable Acidic Oxygen Evolution

The development of low‐cost, highly active, and durable nonprecious metal acid oxygen evolution reaction (OER) electrocatalysts is a key bottleneck for the large‐scale commercialization of proton exchange membrane water electrolyzers. Despite the promising prospects of manganese (Mn)‐based oxides, they face a severe “activity‐stability” trade‐off due to the high solubility of highly active Mn 3+ species in acidic media. This article reports a simple one‐step heating strategy that successfully synthesized lanthanum (La)‐doped MnO 2 / Mn 2 O 3 on carbon cloth. The introduction of large‐radius La 3+ ions induced significant lattice distortion and charge compensation, successfully enriching the active Mn 3+ species and generating abundant oxygen vacancies. The leaching of unstable La triggered in situ deep hydroxylation, forming a dense passivation layer. This restructured surface not only facilitates rapid proton transport but also provides significant protection for the internal framework against acid corrosion. As a result, the optimized La3‐MnO X catalyst exhibits outstanding acidic OER performance, with an overpotential of only 294 mV at a current density of 10 mA/cm 2 , and maintains stability for over 110 h in 0.5 M H 2 SO 4 . This study proposes a novel rare‐earth‐element‐inducing strategy for the design of high‐performance electrocatalysts for OER.