Asymmetric Coordination of Single-Atom Ru Sites Achieves Efficient N(sp3)–H Dehydrogenation Catalysis for Ammonia Oxidation
Ruthenium single-atom catalysts have great potential in ammonia-selective catalytic oxidation (NH3–SCO); however, the stable sp3 hybrid orbital of NH3 molecules makes N(sp3)–H dissociation a challenge for conventional symmetrical metallic oxide catalysts. Herein, we propose a heterogeneous interface reverse atom capture strategy to construct Ru with unique asymmetric Ru1N2O1 coordination. Ru1N2O1/CeO2 exhibits intrinsic low-temperature conversion (T100 at 160 °C) compared to symmetric coordinated Ru-based (280 °C), Ir-based (220 °C), and Pt-based (200 °C) catalysts, and the TOF is 65.4 times that of Ag-based catalysts. The experimental and theoretical studies show that there is a strong d–p orbital interaction between Ru and N atoms, which not only enhances the adsorption of ammonia at the Ru1N2O1 position but also optimizes the electronic configuration of Ru. Furthermore, the affinity of Ru1N2O1/CeO2 to water is significantly weaker than that of conventional catalysts (the binding energy of the Pd3Au1 catalyst is −1.19 eV, but it is −0.39 eV for our material), so it has excellent water resistance. Finally, the N(sp3)–H activation of NH3 requires the assistance of surface reactive oxygen species, but we found that asymmetric Ru1N2O1 can directly activate the N(sp3)–H bond without the involvement of surface reactive oxygen species. This study provides a novel principle for the rational design of the proximal coordination of active sites to achieve its optimal catalytic activity in single-atom catalysis.
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