Time-resolved DRIFTS, MS, and resistance study of SnO2 materials: The role of surface hydroxyl groups in formation of donor states

Roman G. Pavelko, Helen Daly, Michael Hübner, Christopher Hardacre, Eduard Llobet

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Time-resolved DRIFTS, MS, and resistance measurements were used to study the interaction of undoped and Pd-doped SnO2 with H2 in air and argon at 300 °C. Using first-order kinetics, we compare the time constants for the resistance drop and its partial recovery with those of the surface hydroxyl evolution and water formation in the gas phase upon exposure to hydrogen. In the case of the undoped oxide, resistance and bridging hydroxyls (BOHs) evolve similarly, manifesting a fast main drop followed by recovery at a similar rate. The rate of water formation for this material was found to be much slower than that of the main drop in both the resistance and BOHs. In contrast, the resistance change for SnO2-Pd appeared to be similar to that of water formation, and no correlation was found between the evolution of resistance and surface OHs. Isotopic exchange on both materials revealed that water formation occurs via fast and slow hydrogen transfer to surface oxygen species. While the former originates from just-adsorbed hydrogen, the latter appears to proceed from the preadsorbed OHs. Both surfaces exhibit close interaction between chemisorbed oxygen and existing bridging OH groups, indicating that the latter is an intermediate in the hydrogen oxidation and generation of donor states on the surface.

    Original languageEnglish
    Pages (from-to)4158-4167
    Number of pages10
    JournalJournal of Physical Chemistry C
    Volume117
    Issue number8
    DOIs
    Publication statusPublished - 2013

    Fingerprint

    Dive into the research topics of 'Time-resolved DRIFTS, MS, and resistance study of SnO2 materials: The role of surface hydroxyl groups in formation of donor states'. Together they form a unique fingerprint.

    Cite this