Pluralistic Electronic Structure Modulation of Ruthenium Oxide for Enhanced Acidic Water Electrolysis

Proton exchange membrane water electrolysis (PEMWE) with high-purity H₂ and O₂ products and swift response to electricity fluctuation is of great interest for renewable energy, chemical and pharmaceutical industries. Ruthenium oxide shows promise as an alternative to iridium oxide catalysts in PEMWE but suffers from severe anodic corrosion. Herein, a pluralistic electronic structure modulation approach is presented to address the instability issue of Ru, by in situ growing Mn_xRu_1−xO₂ solid solution on MnO₂, coated carbon fibers (Mn_xRu_1−xO₂/MnO₂/CFs). Due to higher ion electronegativity, Mn dopants in the Mn_xRu_1−xO₂ solid solution accept electrons, activating the Ru site. Simultaneously, the MnO₂ support donates electrons to prevent Ru site overoxidation and dissolution due to its lower work function than the Mn_xRu_1−xO₂ solid solution. As a result, the Mn_xRu_1−xO₂/MnO₂/CFs catalyst exhibits a low overpotential of 161 mV at 10 mA cm⁻² and a remarkable stability exceeding 600 h. Profiting by its improved oxygen evolution reaction (OER) kinetic activity, the Mn_xRu_1−xO₂/MnO₂/CF-based PEMWE shows a low cell voltage of 1.9 V at 2 A cm⁻², and stably operate at current density of 500 mA cm⁻² for 24 h. This work shows the potential of the pluralistic electronic structure modulation to boost activity and stability of Ru-based acidic OER electrocatalysts.