Behavior of Photogenerated Electron–Hole Pair for Water Splitting on TiO2(110)

As a typical photocatalyst, TiO 2 has been intensively studied for water splitting. However, the mechanism, especially how photogenerated holes participate in, behind the reaction remains highly debated. It is fundamental to identify the capability of groups at the TiO 2 /water interface to attract photogenerated holes. In this work, we applied the first-principles many-body Green’s function theory to investigate the behaviors of free photogenerated holes and coupled electron–hole pairs at three kinds of TiO 2 /water interfaces. Our calculations show that interaction between TiO 2 and water elevates their respective valence band edges significantly. The groups derived from water, including Ti–OH, OH –, and H 2 O, cannot be oxidized by holes from photons at the optical absorption edge of TiO 2 . With higher-energy UV light, holes may be trapped by Ti–OH and OH – . However, these holes might eventually decay onto three-coordinated lattice O atoms both with and without the presence of photoelectrons if they cannot participate in the oxygen evolution reaction in time. Species related to water may only act as reactants in the photooxidation reaction. There must be some other configurations on TiO 2 (110), which are unknown yet and may emerge with the excited-state dynamics process, that provide active sites for holes to promote the photooxidation reaction.