A Quantitative Structural Investigation of the 0.1 wt % Nb-SrTiO3(001)/H2O Interface

H Hussain; X Torrelles; P Rajput; M Nicotra; G Thornton; J Zegenhagen

doi:10.1021/jp5034118

A Quantitative Structural Investigation of the 0.1 wt % Nb-SrTiO₃(001)/H₂O Interface

J Phys Chem C Nanomater Interfaces. 2014 May 22;118(20):10980-10988. doi: 10.1021/jp5034118. Epub 2014 Apr 23.

Authors

H Hussain¹, X Torrelles², P Rajput³, M Nicotra⁴, G Thornton⁴, J Zegenhagen³

Affiliations

¹ London Centre for Nanotechnology and Department of Chemistry, University College London , 20 Gordon Street, London WC1H OAJ, United Kingdom ; ESRF , 6 rue Jules Horowitz, F-38000 Grenoble cedex, France.
² Institut de Ciència de Materials de Barcelona (CSIC) , Campus UAB, 08193 Bellaterra, Spain.
³ ESRF , 6 rue Jules Horowitz, F-38000 Grenoble cedex, France.
⁴ London Centre for Nanotechnology and Department of Chemistry, University College London , 20 Gordon Street, London WC1H OAJ, United Kingdom.

Abstract

Surface X-ray diffraction has been employed to elucidate the structure of the interface between a well-characterized (001) surface of 0.1 wt % Nb-SrTiO₃ and liquid H₂O. Results are reported for the clean surface, the surface in contact with a drop of liquid water, and the surface after the water droplet has been removed with a flow of nitrogen. The investigation revealed that the clean surface, prepared via annealing in 1 × 10^-2 mbar O₂ partial pressure, is unreconstructed and rough on a short length scale. The surface is covered with large terraces, the topmost layer of which is either TiO₂ or SrO with an area ratio of about 7/3. For the surface in contact with water, our results reveal that associative H₂O adsorption is favored for the TiO₂-terminated terrace whereas adsorption is dissociative for the SrO-terminated terrace, which validates recent first-principles calculations. After removal of the water droplet, the surface largely resembles the water-covered surface but now with a disordered overlayer of water present on the surface.