Dual Synergistic Effects in a Ce‐Modified MnO ₂ /MnO Heterostructure Enabling Outstanding Acidic Oxygen Evolution

ABSTRACT The development of highly efficient and stable nonprecious metal electrocatalysts for the acidic oxygen evolution reaction (OER) is crucial to advance proton exchange membrane (PEM) water electrolysis. In this work, a dual synergistic strategy was proposed by constructing a Ce‐modified MnO 2 /MnO heterostructure. The catalyst exhibited outstanding OER performance, achieving a low overpotential of 335 mV at 10 mA cm −2 in 0.5 M H 2 SO 4 , along with exceptional long‐term stability, sustaining operation for 115 h at a high current density of 1 A cm −2 . Mechanistic studies revealed that the outstanding performance originates from the dual synergistic effects: The built‐in electric field at the heterointerface optimizes the adsorption of oxygen intermediates and alters the rate‐determining step; the introduced Ce species, through orbital hybridization and charge transfer enhancement, promotes reaction kinetics. Furthermore, the electron‐deficient state of MnO 2 induced by the internal electric field effectively suppresses excessive Mn dissolution, ensuring exceptional stability in acidic media.