Effect of niobium segregation on the surface properties of titanium dioxide

Leigh R. Sheppard, Armand J. Atanacio, Tadeusz Bak, Janusz Nowotny, Kathryn E. Prince, Lionel Vayssieres

    Research output: Chapter in Book / Conference PaperConference Paper

    Abstract

    The present paper considers the effect of segregation on the performance of photo-electrode materials for photo-electrochemical water splitting. This phenomenon, which alters the surface composition of a material during processing at elevated temperatures, has the capacity to dominate interfacial charge transfer between the photo-electrode and the electrolyte. As the present understanding of segregation in metal oxides is limited, this paper aims at addressing the need to collect empirical data which can be used for the development of novel materials. In the present investigation, Nb surface segregation was investigated at 1273 K under high and low oxygen activity using secondary ion mass spectrometry (SIMS). A calibration procedure was used to enable quantifiable data and Nb was observed to segregate strongly, especially at high oxygen activity. While this was attributed to the defect disorder, it remained unclear whether gas/solid equilibrium was achieved, and consequently whether the observed behaviour represents equilibrium segregation. Irrespectively, the observed behaviour clearly illustrates how the surface composition of a metal oxide can be altered through the control of segregation. This must be considered in the pursuit of high performance photo-electrode materials for water splitting under sunlight.
    Original languageEnglish
    Title of host publicationSolar Hydrogen and Nanotechnology: Proceedings of SPIE, the International Society for Optical Engineering: 14-17 August 2006, San Diego, California, USA
    PublisherSPIE
    Number of pages1
    ISBN (Print)0819464198
    Publication statusPublished - 2006
    EventInternational Society for Optical Engineering. Conference -
    Duration: 1 Jan 2006 → …

    Conference

    ConferenceInternational Society for Optical Engineering. Conference
    Period1/01/06 → …

    Keywords

    • titanium dioxide
    • niobium
    • segregation
    • water splitting
    • solar energy
    • photoelectrochemistry

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