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

Proton exchange membrane water electrolysis (PEMWE) with high‐purity H 2 and O 2 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 x Ru 1− x O 2 solid solution on MnO 2 , coated carbon fibers (Mn x Ru 1− x O 2 /MnO 2 /CFs). Due to higher ion electronegativity, Mn dopants in the Mn x Ru 1− x O 2 solid solution accept electrons, activating the Ru site. Simultaneously, the MnO 2 support donates electrons to prevent Ru site overoxidation and dissolution due to its lower work function than the Mn x Ru 1− x O 2 solid solution. As a result, the Mn x Ru 1− x O 2 /MnO 2 /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 x Ru 1− x O 2 /MnO 2 /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.