Surface coordination structure of support governs ag-catalyzed formaldehyde oxidation by regulating formate adsorption and CH activation

Supports play a pivotal role in noble metal-supported catalysts by regulating the dispersion, electronic structure, and interfacial interactions of active species, as well as influencing the adsorption and activation of reactants. Herein, we demonstrated that the coordination structure of oxide supports critically dictates the catalytic performance of Ag-based catalysts in formaldehyde (HCHO) oxidation. Although Ag/Al 2 O 3 and Ag/TiO 2 possessed comparable Ag particle sizes, oxidation states, and redox properties, their activities differed substantially: Ag/Al 2 O 3 achieved complete HCHO conversion at 80 °C, while Ag/TiO 2 required 170 °C under identical conditions. In situ DRIFTS results revealed that HCHO was transformed into formate intermediates on both supports, but Al 2 O 3 stabilized two distinct formate configurations, whereas TiO 2 favored a single adsorption mode. More importantly, formates on Ag/Al 2 O 3 decomposed at much lower temperatures than those on Ag/TiO 2 , suggesting enhanced intermediate reactivity. Density functional theory (DFT) calculations confirmed that the diverse coordination environments of surface Al atoms enable multiple formate adsorption modes with lower C H bond dissociation barriers compared to Ti sites. These results establish that the support coordination structure governs intermediate configurations and their transformation kinetics, offering mechanistic insights into the superior oxidation activity of Ag/Al 2 O 3 and providing guidance for the rational design of efficient Ag-based catalysts for HCHO purification.