Design and synthesis of Pt/TiO2 catalyst with abundant surface hydroxyl for formaldehyde oxidation
Zhaoyu Zhong, Muhua Chen, Xuelin Huang, Ping Wang
Abstract
Catalytic oxidation of formaldehyde (HCHO) is a highly effective method for indoor HCHO removal. However, many aspects of the catalytic mechanism remain unclear, making the optimization of catalysts largely empirical. Herein, we report a coupled experimental and computational study of Pt/TiO 2 catalysts, with special focus on the functional roles of surface oxygen vacancies and hydroxyl groups in the catalytic oxidation of HCHO . DFT calculations combined with control experiments revealed that the formation of surface oxygen vacancies on TiO 2 and their capability in facilitating H 2 O dissociation are strongly dependent on the exposed facets. Correlating these facet-dependent properties with the determined activity further indicated that the catalytic performance is directly related to the abundance of surface hydroxyl groups , rather than surface oxygen vacancies as commonly assumed. Guided by these insights, we employed a combination of facet-engineering and alkali metal modification strategies to design a potassium-modified Pt/TiO 2 catalyst with predominantly exposed {100} facets (denoted as Pt/TiO 2 {100}-K). The Pt/TiO 2 {100}-K catalyst showed an impressively high mass-specific reaction rate of 105.7 μmol g Pt −1 s −1 , along with fairly good stability and moisture tolerance. Further investigations using in situ DRIFTS coupled with on-line GC provided additional insight into the reaction mechanism of HCHO oxidation over the Pt/TiO 2 {100}-K catalyst.