Regensburg 2019 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 13: Solid-Liquid Interfaces I: Electrocatalysis and Photoelectrochemistry
O 13.9: Vortrag
Montag, 1. April 2019, 17:00–17:15, H16
Interfacial water reorientation after UV irradiation of TiO2 — •Shumei Sun1, Saman Hosseinpour1, Simon Schlegel1, Mischa Bonn1, and Ellen Backus1,2 — 1Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany — 2Department of Physical Chemistry, University of Vienna
Clean energy like hydrogen can be generated on TiO2 by photocatalytic water splitting with UV light, which was discovered more than 40 years ago. Since then, tremendous research efforts on TiO2 have been driven by the potential benefits for renewable energy. However, the mechanism behind photocatalysis is still unclear. Sum frequency vibrational spectroscopy as a surface sensitive technique allows us to probe the interface of TiO2/water. Here we use a femtosecond UV pulse as pump to excite TiO2. Subsequently, sum frequency vibrational spectroscopy is used as probe to monitor the response of water molecules to UV excitation of TiO2. Preliminary results show that electron and holes generated in the TiO2 by UV excitation recombine on a few hundred picoseconds timescale. Moreover, the interfacial structure seems to change on a sub-ps timescale, showing differences depending on the pH of the solution. Our results show that UV pump-SFG probe is a powerful tool to unravel the mechanism of a photon induced surface reaction.