Anatase TiO₂(001)-(1 × 4) Surface Is Intrinsically More Photocatalytically Active than the Rutile TiO₂(110)-(1 × 1) Surface

Aligning the intrinsic photocatalytic activities of various types of TiO 2 facets is of great importance and interest in TiO 2 photocatalysis. Herein, we report a comparative study of the intrinsic photocatalytic activities of anatase TiO 2 (001)-(1 × 4) and rutile TiO 2 (110)-(1 × 1) surfaces probed by photostimulated desorption of O 2 with combined thermal desorption spectroscopy, photostimulated desorption spectroscopy, and density functional theory calculations. Photostimulated desorption behavior of O 2 depends on both TiO 2 surface structures and O 2 adsorption configurations. O 2 species adsorbed on the anatase TiO 2 (001)-(1 × 4) surface exhibit a higher intrinsic photostimulated desorption reactivity than those on the rutile TiO 2 (110)-(1 × 1) surface, which can be associated with their electronic structures and subsequent hole transfer processes from TiO 2 . These results provide, for the first time, direct and unambiguous experimental evidence for the higher intrinsic photocatalytic activity of the anatase TiO 2 (001) facet than those of other TiO 2 facets and highlight the key role of structures of both TiO 2 surfaces and adsorbed species in TiO 2 photocatalysis.