Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 45: Poster: Solid-Liquid Interfaces - Structure, Spectroscopy, Reactions and Electrochemistry

O 45.10: Poster

Dienstag, 13. März 2018, 18:15–20:30, Poster A

Towards understanding the mechanism of water splitting on TiO2 — Saman Hosseinpour, Simon J. Schlegel, Mischa Bonn, and •Ellen H.G. Backus — Max Planck Institute for Polymer Research, Mainz, Germany

Finding a clean and renewable energy source to replace fossil fuels has attracted much attention, the past few decades, as a requirement for the sustainable development of societies. Direct hydrogen generation on TiO2 by photocatalytic dissociation of water using sunlight was already proposed more than 40 years ago. However, despite extensive work in this area, the fundamentals of the process remain ill-understood, mainly due to the lack of a proper tool to specifically explore the interface between water and TiO2. Sum frequency generation spectroscopy (SFG), is an inherently surface sensitive tool, allowing the study of the water-TiO2 interface. As a first step in understanding the water-splitting reaction, we studied the binding of water to the substrate. From the intensity and frequency of the SFG signal we extract information about the binding of water to the TiO2. Moreover, we show time-resolved SFG data after excitation of the TiO2 with a femtosecond UV pump pulse which mimics the sun light. Preliminary data show that both the surface and the interfacial water molecules undergo changes on ultrafast timescales upon excitation. These UV-pump SFG-probe data illustrate the first steps towards following the photo-induced dissociation of water at the TiO2 interface in real-time.