Manipulating the H2O2 Reactivity on Pristine Anatase TiO2 with Various Surface Features and Implications in Oxidation Reactions

Abstract

Anatase TiO₂ is commonly used as a catalyst/support in reactions involving H₂O₂, yet the understanding of interactions between common TiO₂ surfaces and H₂O₂ remains limited. Herein, we synthesized well-defined TiO₂ crystallites with (101), (001), and fluorine-modified (001) [F-(001)] surfaces to examine how surface features, including the arrangement of five-coordinated Ti (Ti_5c) sites and the presence of fluorine, influence H₂O₂ activation. Our findings reveal that these surface features significantly affect the physiochemical properties of adsorbed H₂O₂. Specifically, fluorine on the F-(001) surface introduces an additional hydrogen bond to the Ti_5c-peroxo species, altering the electronic structure of H₂O₂ compared to those with the (101) and (001) surfaces. Using cyclohexene as a probe substrate, we successfully distinguished the reactivities of the Ti_5c-peroxo species. The activity of those on the F-(001) surface was significantly higher than the activity of those on the (001) surface, while the (101) surface showed negligible oxidation activity. These insights can guide the design of TiO₂-based catalysts for H₂O₂-related reactions.