Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 55: Metal Oxide Surfaces III: Adsorption and Reactivity

O 55.11: Vortrag

Mittwoch, 3. April 2019, 17:30–17:45, H5

Probing Photoexcited Charge Dynamics of Single Oxygen Vacancies on TiO2(110) at Atomic Scale — •chaoyu guo, xiangzhi meng, qin wang, and ying jiang — Peking University, Peking, China

A Titanium dioxide (TiO2) is well known as one of the most widely studied materials in photocatalysis and solar energy conversion. Photoexcited charge dynamics of near-surface defects such as oxygen vacancies plays a critical role in the photocatalytic process of TiO2, but the atomic-scale mechanism is yet to be elucidated. With laser-combined scanning tunneling microscopy, tracking carrier dynamics with high spatial and temporal resolution simultaneously is possible. Here we succeeded to probe the photoexcitation and transient relaxation process of individual oxygen vacancies on rutile TiO2(110) surface. Upon visible-laser illumination, the in-gap states derived from surface oxygen vacancies exhibit prominent downward energy shift accompanied with a suppression of valence tail states, which were attributed to photoexcited electronic transition between the defect levels and conduction band. We found that the photogenerated electrons and holes exhibit rather different carrier dynamics due to the atomic-scale environment variation. Those results shed new lights onto the visible photoresponse of reduced-TiO2 materials and reveal the influence of atomic defects on the electron-hole recombination dynamics in real space.