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Direct visualization of defect-mediated dissociation of water on TiO2(110)

Nature Materials volume 5, pages 189–192 (2006)Cite this article

Abstract

The chemistry of metal oxide surfaces has long been thought to be dominated by reactions involving defects1,2. These are minority sites such as oxygen vacancies. Thus far, it has proved difficult to obtain direct experimental evidence to support this idea, although some progress has been made3,4,5. Here, we use the scanning tunnelling microscope (STM) to image the reaction of water molecules with bridging-oxygen vacancies on a model oxide surface, rutile TiO2(110). In a form of single-molecule chemistry, individual oxygen vacancies are observed being transformed into OH species as a water molecule dissociates in the vacancy. We use the STM tip to selectively desorb individual H atoms, whilst leaving the vacancies intact. This allows us to distinguish between vacancies and OH, which have a similar appearance in STM. In a very clear way, these results validate the view that defects can play a key role in oxide surface reactions.

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Figure 1: Schematic depictions of reactions on TiO2(110).
Figure 2: Sequential 150×150 Å2 STM images of as-prepared TiO2(110).
Figure 3: Sequential (285 Å×250 Å) STM images of TiO2(110) recorded at 1.5 V, 0.2 nA.
Figure 4: Reaction of O2 with O vacancies on TiO2(110).

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Acknowledgements

This work was funded by EPSRC (UK), an EU 5th framework grant (OXIDESURFACES), CREST of JST (Japan) and a Royal Society (UK)–JSPS (Japan) grant for collaboration. C.L.P. is grateful to JSPS (Japan) for the award of a Research Fellowship.

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Author notes

  1. Oier Bikondoa and Chi L. Pang: These authors contributed equally to this work

Authors and Affiliations

  1. School of Chemistry, University of Manchester, Manchester, M13 9PL, UK

    Oier Bikondoa & Christopher A. Muryn

  2. Department of Chemistry, Faculty of Science, Kobe University, Kobe, 657-8501, Japan

    Chi L. Pang & Hiroshi Onishi

  3. Pusat Asasi Sains, Universiti Malaya, 50603, Kuala Lumpur, Malaysia

    Roslinda Ithnin

  4. London Centre for Nanotechnology and Chemistry Department, University College London, 20 Gordon Street, London, WC1H 0AJ, UK

    Geoff Thornton

Authors
  1. Oier Bikondoa
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  4. Christopher A. Muryn
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  5. Hiroshi Onishi
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  6. Geoff Thornton
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Correspondence to Geoff Thornton.

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Bikondoa, O., Pang, C., Ithnin, R. et al. Direct visualization of defect-mediated dissociation of water on TiO2(110) . Nature Mater 5, 189–192 (2006). https://doi.org/10.1038/nmat1592

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