Water adsorption, dissociation and oxidation on SrTiO <inf>3</inf> and ferroelectric surfaces revealed by ambient pressure X-ray photoelectron spectroscopy

Neus Domingo, Elzbieta Pach, Kumara Cordero-Edwards, Virginia Pérez-Dieste, Carlos Escudero, Albert Verdaguer

    Research output: Contribution to journalArticleResearch

    16 Citations (Scopus)

    Abstract

    © 2019 the Owner Societies. Water dissociation on oxides is of great interest because its fundamental aspects are still not well understood and it has implications in many processes, from ferroelectric polarization screening phenomena to surface catalysis and surface chemistry on oxides. In situ water dissociation and redox processes on metal oxide perovskites which easily expose TiO 2 -terminated surfaces, such as SrTiO 3 , BaTiO 3 or Pb(Zr,Ti)O 3 , are studied by ambient pressure XPS, as a function of water vapour pressure. From the analysis of the O1s spectrum, we determine the presence of different types of oxygen based species, from hydroxyl groups, either bound to Ti 4+ and metal sites or lattice oxygen, to different peroxide compounds, and propose a model for the adsorbate layer composition, valid for environmental conditions. From the XPS analysis, we describe the existing surface redox reactions for metal oxide perovskites, occurring at different water vapour pressures. Among them, peroxide species resulting from surface oxidative reactions are correlated with the presence of Ti 4+ ions, which are observed to specifically promote surface oxidation and water dissociation as compared to other metals. Finally, surface peroxidation is enhanced by X-ray beam irradiation, leading to a higher coverage of peroxide species after beam overexposure and by ferroelectric polarization, demonstrating the enhancement of the reactivity of the surfaces of ferroelectric materials due to the effect of internal electric fields.
    Original languageEnglish
    Pages (from-to)4920-4930
    JournalPhysical Chemistry Chemical Physics
    Volume21
    DOIs
    Publication statusPublished - 1 Jan 2019

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