Different Activation Mechanisms of Oxygen and Water during Formaldehyde Oxidation on Pt/Anatase Catalysts: The Effect of Pt Geometric Configurations

Supported noble metal catalysts are highly promising candidates for room-temperature formaldehyde (HCHO) removal. The geometric configuration and the electronic environment of the noble metal component in these catalysts directly govern catalytic performance. Elucidating the effects of the structural and electronic properties of supported noble metal catalysts on HCHO oxidation, particularly the catalytic mechanism of oxygen and H 2 O, which are the two critical reactants in the reaction atmosphere during the HCHO oxidation, remains unclear. Morever, active hydroxyl groups generated from the oxygen and/or H 2 O are crucial for the decomposition of formate species, which is the rate-determining step of the reaction. Herein, two Pt/TiO 2 catalysts with distinct Pt configurations were fabricated: one dominated by Pt nanoparticles (Pt NP -TiO 2 ) and the other by highly exposed Pt species (Pt HE -TiO 2 ). Using multiple characterization techniques, the structure–activity relationships between Pt configurations and HCHO oxidation mechanisms were systematically investigated. Specifically, Pt NP -TiO 2 possesses a predominant Pt-Pt coordination configuration, which endows the catalyst with better intrinsic oxygen activation capability. Therefore, water acts as a co-reactant involved in a water-oxygen synergistic mechanism (2Pt NP * + O 2 → 2Pt NP -O*; Pt NP -O* + H 2 O → Pt NP -OH*). In contrast, Pt HE -TiO 2 features a Pt-O coordination environment that impairs its intrinsic oxygen activation performance. Water here serves as an essential auxiliary agent to facilitate oxygen activation via the water-assisted oxygen activation pathway (Pt HE * + O 2 → Pt HE -O 2 *; Pt HE -O 2 * + H 2 O → Pt HE -OOH* + Pt HE -OH*). This work clarifies the intrinsic role of Pt active sites under different coordination environments and provides theoretical support for the precise design of high-performance room-temperature HCHO oxidation catalysts.