Phase engineering boosting heterogeneous interface effect in RuO2/MnO2 catalysts for acidic oxygen evolution reaction

Oxygen evolution reaction (OER) of ruthenium dioxide (RuO2) in acidic media usually faces the problem of poor stability caused by excessive oxidation and dissolution. To address this issue, the present work prepares heterojunction catalysts by introducing RuO2 into manganese dioxide (MnO2) with different crystal types. The obtained RuO2/MnO2-γ exhibited excellent acid OER activity (η = 220 mV at 10 mA·cm−2) and could operate stably for 80 h. Mainly because the Ru-O-Mn bonds generated at the RuO2/MnO2-γ heterointerface fine-tune the charge environment of RuO2. The formation of this particular interface can enable MnO2-γ to produce more reactive oxygen defects, which promotes the transfer of electrons. At the same time, it can also minimize the peroxidation reaction and structural collapse of RuO2 under acidic conditions, thereby suppressing the Lattice Oxygen Mechanism (LOM) to improve stability. Density functional theory (DFT) results show that RuO2/MnO2-γ lowers the energy barrier for the *O to *OOH conversion. This research findings provides a new perspective for elucidating the role of the regulated electronic environment arising from heterogeneous interfaces.