Water adsorption, dissociation and oxidation on SrTiO3 and ferroelectric surfaces revealed by ambient pressure X-ray photoelectron spectroscopy
Domingo Marimon, Neus (Institut Català de Nanociència i Nanotecnologia)
Pach, Elzbieta (Institut Català de Nanociència i Nanotecnologia)
Cordero Edwards, Rohini Kumara (Institut Català de Nanociència i Nanotecnologia)
Pérez-Dieste, Virginia (ALBA Laboratori de Llum de Sincrotró)
Escudero, Carlos (ALBA Laboratori de Llum de Sincrotró)
Verdaguer Prats, Albert (Institut de Ciència de Materials de Barcelona)

Data:	2019
Resum:	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-terminated surfaces, such as SrTiO, BaTiO or Pb(Zr,Ti)O, 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 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 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.
Ajuts:	Ministerio de Economía y Competitividad MAT2016-77852-C2-1-R Ministerio de Economía y Competitividad FIS2015-73932-JIN Ministerio de Economía y Competitividad SEV-2015-0496 Ministerio de Economía y Competitividad SEV-2013-0295 Agència de Gestió d'Ajuts Universitaris i de Recerca 2017/SGR-668 Agència de Gestió d'Ajuts Universitaris i de Recerca 2017/SGR-579
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Matèria:	Ambient pressure xps ; Ambient-pressure x-ray photoelectron spectroscopies ; Environmental conditions ; Ferroelectric polarization ; Ferroelectric surfaces ; Internal electric fields ; TiO2-terminated surfaces ; Water vapour pressure
Publicat a:	Physical chemistry chemical physics, Vol. 21, issue 9 (March 2019) , p. 4920-4930, ISSN 1463-9076

DOI: 10.1039/c8cp07632d
PMID: 30758026

Postprint 33 p, 1.2 MB

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