Visualizing dual-sites synergistic catalysis in non-iridium catalysts for acidic oxygen evolution reaction

Understanding electron transfer at the solid/liquid electrochemical interface is critical for deciphering synergistic catalysis, yet elucidating how metal dopants mediate charge transfer between adjacent active centers remains challenging. Here, we incorporate a series of metal dopants (Cu, Mn, W) into RuO2 to investigate how dual-site (M–Ru) electron transfer affects catalytic activity and stability. Combining in situ characterization with theoretical simulations, we reveal that Mn doping intensifies Ru 4d–O 2p orbital coupling and establishes unidirectional electron transfer, which peroxidizes Ru under high voltage and accelerates performance degradation. In contrast, W doping modulates the Ru 4d- and O 2p-band centers to reduce orbital overlap, weakening Ru–O covalency and enabling bidirectional electron transfer. Functioning as a voltage-gated electron regulator, the W site dynamically switches roles: at low potentials it acts as an electron acceptor to activate Ru sites and promote water dissociation, while at high potentials it serves as an electron donor to suppress Ru peroxidation. This mechanism endows the catalyst with good stability, showing negligible activity decay during 300 hours of operation at 500 mA cm⁻². Understanding electron transfer dynamics at the solid–liquid interface is critical for deciphering the mechanism of acidic oxygen evolution. Here, the authors reveal that the dynamic bidirectional electron transfer between W and Ru dual sites underpins the enhanced performance of Ru-based catalysts.