Water-Induced Reversal of the TiO2(011)-(2 × 1) Surface Reconstruction: Observed with in Situ Surface X-ray Diffraction

Hadeel Hussain; Mahmoud H M Ahmed; Xavier Torrelles; David C Grinter; Gregory Cabailh; Oier Bikondoa; Christopher Nicklin; Ulrich Aschauer; Robert Lindsay; Geoff Thornton

doi:10.1021/acs.jpcc.9b04383

Water-Induced Reversal of the TiO₂(011)-(2 × 1) Surface Reconstruction: Observed with in Situ Surface X-ray Diffraction

J Phys Chem C Nanomater Interfaces. 2019 Jun 6;123(22):13545-13550. doi: 10.1021/acs.jpcc.9b04383. Epub 2019 May 13.

Authors

Hadeel Hussain^{1

2}, Mahmoud H M Ahmed^{1

2}, Xavier Torrelles³, David C Grinter⁴, Gregory Cabailh⁵, Oier Bikondoa^{6

7}, Christopher Nicklin⁸, Ulrich Aschauer⁹, Robert Lindsay^{1

2}, Geoff Thornton⁴

Affiliations

¹ Corrosion and Protection Centre, School of Materials, The University of Manchester, Sackville Street, M13 9PL Manchester, U.K.
² Photon Science Institute, The University of Manchester, M13 9PL Manchester, U.K.
³ Institut de Ciència de Materials de Barcelona (CSIC), Campus UAB, 08193 Bellaterra, Spain.
⁴ London Centre for Nanotechnology and Department of Chemistry, University College London, 20 Gordon Street, WC1H OAJ London, U.K.
⁵ Sorbonne Université, UMR CNRS 7588, Institut des NanoSciences de Paris, 4 place Jussieu, 75252 Paris Cedex 05, France.
⁶ XMaS, The UK-CRG Beamline. ESRF, The European Synchrotron, 71, Avenue des Martyrs, CS40220, F-38043 Grenoble cedex 09, France.
⁷ Department of Physics, University of Warwick, Gibbet Hill Road, CV4 7AL Coventry, U.K.
⁸ Diamond Light Source Limited, Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, U.K.
⁹ Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland.

Abstract

The (011) termination of rutile TiO₂ is reported to be particularly effective for photocatalysis. Here, the structure of the interface formed between this substrate and water is revealed using surface X-ray diffraction. While the TiO₂(011) surface exhibits a (2 × 1) reconstruction in ultra-high vacuum (UHV), this is lifted in the presence of a multilayer of water at room temperature. This change is driven by the formation of Ti-OH at the interface, which has a bond distance of 1.93 ± 0.02 Å. The experimental solution is in good agreement with density functional theory and first-principles molecular dynamics calculations. These results point to the important differences that can arise between the structure of oxide surfaces in UHV and technical environments and will ultimately lead to an atomistic understanding of the photocatalytic process of water splitting on TiO₂ surfaces.