The fabrication of Mn single atoms/clusters on Al₂O₃ for enhanced catalytic NO oxidation

The exploitation of transitional metal catalysts for high-efficient conversion of NO to NO₂ still persists as an imperative issue due to the high cost of currently used Pt–based catalysts. Herein, we report a TEA-modification strategy to anchor Mn single atoms/clusters on Al₂O₃ (Mn/Al₂O₃-T) for NO oxidation. Activity tests show that Mn/Al₂O₃-T (T₈₃ = 275 °C) displays a superior NO-to-NO₂ capacity compared with the unmodified Mn nanoparticle on Al₂O₃ (Mn/Al₂O₃-B, T₆₆ = 300 °C) and Pt/Al₂O₃ (T₄₃ = 350 °C) counterparts. Comprehensive characterization and DFT calculations discover that the effective adjustment of TEA can promote the generation of coordination unsaturated Mn sites with elongated Mn-O bonds, which can improve the mobility of surface lattice oxygen and facilitate the activation of molecular oxygen. Additionally, reducing Mn size from nanoparticles to single atoms/clusters favors the formation of labile nitrate species and facile desorption of NO₂, thereby regenerating active sites and accelerating overall NO oxidation reaction.