Dynamic Electron Regulation in Titanium Felt Supported RuO ₂ /MnO ₂ Nanoheterointerface for Acidic Oxygen Evolution

RuO2 is a highly active catalyst for the oxygen evolution reaction (OER) in proton exchange membrane water electrolysis (PEMWE), but its practical application is hindered by severe overoxidation and dissolution under harsh acidic conditions. To address this issue, we constructed a RuO2/MnO2 heterostructured nanosphere catalyst on titanium felt (RuO2/MnO2/TF) via a hydrothermal-calcination method. By employing MnO2 as an “electron reservoir,” this interfacial electron-modulation strategy aims to optimize the catalytic performance of RuO2. Theoretical and experimental analyses indicate that a close nanoscale heterointerface forms between RuO2 and MnO2, with electron transfer occurring from Ru to Mn at the interface. During the OER process, the Mn3+/Mn4+ redox couple dynamically regulates the valence state of Ru, effectively suppressing its overoxidation and dissolution, thereby enhancing activity in the early reaction stage and improving stability throughout the reaction. Owing to this nanoscale heterointerface design, the electrocatalyst achieves a current density of 10 mA cm–2 with a low overpotential of 176 mV in 0.5 M H2SO4 and exhibits remarkable stability for over 250 h at the same current density. When evaluated in a proton exchange membrane water electrolyzer, the catalyst requires only 1.66 V to achieve a current density of 1.0 A cm–2, demonstrating its potential for practical applications. Overall, this work presents a nanoscale heterointerface engineering strategy for designing acidic OER catalysts with both high activity and excellent durability.