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.