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O: Fachverband Oberflächenphysik

O 81: Oxide and Insulator Surfaces III

O 81.8: Vortrag

Donnerstag, 3. April 2014, 17:45–18:00, PHY C 213

Development of a new Phase on TiO₂ (101) Anatase with Reduced Bandgap — •Christian Dette¹, Christopher S. Kley¹, Miguel A. Perez², Paul Punke¹, Christopher Patrick², Feliciano Giustino², Soon J. Jung¹, and Klaus Kern^1,3 — ¹MPI for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany — ²University of Oxford, 16 Parks Road, Oxford OX1 3PH, United Kingdom — ³EPF Lausanne, IPMC, 1015 Lausanne, Switzerland

Nanosized TiO₂ photocatalytic water-splitting technology has great potential for low-cost, environmentally friendly solar-hydrogen production to support the future hydrogen economy. Presently, the solar-to-hydrogen energy conversion efficiency is too low for the technology to be economically sound. The main barriers are the poor activation of TiO₂ by visible light. Hence, our research is focused on the reduction of the band gap to increase the photocatalytic activity in the visible.

We have created a reduced band gap phase (phase II) on the standard surface (phase I) of a natural grown TiO₂ (101) Anatase crystal by a combination of standard cleaning processes. The creation processes are fully reversible. We have taken detailed topography and spectroscopy data at various positions of each phase by using scanning tunnelling microscopy (STM) and spectroscopy (STS). We found a similarity in the electronic configuration between phase II and the [-111] oriented edge of phase I, since both show a reduced ban gap due to a band gap state near the valence band maximum. We will present a structural model of phase II consistent with the experimental data and first-principle density functional theory based calculations.