Single-Atom Ru-Triggered Lattice Oxygen Redox Mechanism for Enhanced Acidic Water Oxidation

Activating the oxygen anionic redox presents a promising avenue for developing highly active oxygen evolution reaction (OER) electrocatalysts for proton-exchange membrane water electrolyzers (PEMWE). Here, we engineered a lattice-confined Ru single atom dispersed on a lamellar manganese oxide (MnO2) cation site. The strong Ru-O bond induced an upward shift in the O 2p band, enhancing metal-oxygen covalency and reshaping the OER mechanism toward lattice oxygen oxidation pathway with increased activity. In situ spectral characterization combined with density functional theory (DFT) calculations revealed that electron transfer from Mn to Ru alleviates the Jahn-Teller effect within the MnO6 octahedral structure, stabilizing the lattice. The layered Ru/MnO2 architecture also promotes the rapid replenishment of oxygen vacancies, preventing structural collapse. As a result, the optimized Ru/MnO2 electrocatalyst achieves an OER overpotential of only 179 mV at 10 mA cm-2 in 0.5 M H2SO4, along with exceptional durability over 1000 h at 100 mA cm-2. Moreover, the Ru/MnO2-based PEM device requires only 1.71 V to reach 1 A cm-2 and shows a durability of 500 h at 500 mA cm-2.