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

Aligning the intrinsic photocatalytic activities of various types of TiO2 facets is of great importance and interest in TiO2 photocatalysis. Herein, we report a comparative study of the intrinsic photocatalytic activities of anatase TiO2(001)-(1 x 4) and rutile TiO2(110)-(1 x 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 TiO2 surface structures and O-2 adsorption configurations. O-2 species adsorbed on the anatase TiO2(001)-(1 x 4) surface exhibit a higher intrinsic photostimulated desorption reactivity than those on the rutile TiO2(110)-(1 x 1) surface, which can be associated with their electronic structures and subsequent hole transfer processes from TiO2. These results provide, for the first time, direct and unambiguous experimental evidence for the higher intrinsic photocatalytic activity of the anatase TiO2(001) facet than those of other TiO2 facets and highlight the key role of structures of both TiO2 surfaces and adsorbed species in TiO2 photocatalysis.