Site Sensitivity of Interfacial Charge Transfer and Photocatalytic Efficiency in Photocatalysis: Methanol Oxidation on Anatase TiO2 Nanocrystals

Photocatalytic oxidation of methanol on various anatase TiO2 nanocrystals was studied by in situ and time-resolved characterizations and DFT calculations. Surface site and resulting surface adsorbates affect the surface band bending/bulk-to-surface charge migration processes and interfacial electronic structure/interfacial charge transfer processes. TiO2 nanocrystals predominantly enclosed by the {001} facets expose a high density of reactive fourfold-coordinated Ti sites (Ti-4c) at which CH3OH molecules dissociate to form the CH3O adsorbate (CH3O(a)(Ti4c)). CH3O(a)(Ti4c) localized density of states are almost at the valence band maximum of TiO2 surface, facilitating the interfacial hole transfer process; CH3O(a)(Ti4c) with a high coverage promotes upward surface band bending, facilitating bulk-to-surface hole migration. CH3O(a)(Ti4c) exhibits the highest photocatalytic oxidation rate constant. TiO2 nanocrystals enclosed by the {001} facets are most active in photocatalytic methanol oxidation.

Automated summary

The study found that Ti sites exposed on {001} facets of anatase TiO2 nanocrystals have a significant impact on the photocatalytic oxidation of methanol, with CH3O(a)(Ti4c) showing high efficiency in photocatalytic oxidation rates.