title: Water adsorption on TiO2 surfaces probed by soft X-ray spectroscopies: bulk materials vs. isolated nanoparticles.
abstract: We describe an experimental method to probe the adsorption of water at the surface of isolated, substrate-free TiO2 nanoparticles (NPs) based on soft X-ray spectroscopy in the gas phase using synchrotron radiation. To understand the interfacial properties between water and TiO2 surface, a water shell was adsorbed at the surface of TiO2 NPs. We used two different ways to control the hydration level of the NPs: in the first scheme, initially solvated NPs were dried and in the second one, dry NPs generated thanks to a commercial aerosol generator were exposed to water vapor. XPS was used to identify the signature of the water layer shell on the surface of the free TiO2 NPs and made it possible to follow the evolution of their hydration state. The results obtained allow the establishment of a qualitative determination of isolated NPs' surface states, as well as to unravel water adsorption mechanisms. This method appears to be a unique approach to investigate the interface between an isolated nano-object and a solvent over-layer, paving the way towards new investigation methods in heterogeneous catalysis on nanomaterials.
authors.affiliation: Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cedex, France.
authors.forename: Safia
authors.initials: S
authors.lastname: Benkoula
authors.affiliation: CEA/IRAMIS/NIMBE/Laboratoire Edifices Nanométriques, CEA Saclay, 91191 Gif-sur-Yvette, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Sublemontier
authors.affiliation: Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cedex, France.
authors.forename: Minna
authors.initials: M
authors.lastname: Patanen
authors.affiliation: Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cedex, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Nicolas
authors.affiliation: Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cedex, France.
authors.forename: Fausto
authors.initials: F
authors.lastname: Sirotti
authors.affiliation: Sorbonne Université UPMC, Univ Paris 6, UMR 7614, Laboratoire de Chimie Physique Matière et Rayonnement, 11 rue Pierre et Marie Curie, 75005 Paris, France.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Naitabdi
authors.affiliation: Laboratoire national de métrologie et d'essais, département "métrologie des gaz et des aérosols", 1 rue Gaston Boissier, 75724 Paris Cedex 15.
authors.forename: François
authors.initials: F
authors.lastname: Gaie-Levrel
authors.affiliation: Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cedex, France.
authors.forename: Egill
authors.initials: E
authors.lastname: Antonsson
authors.affiliation: Institut Lavoisier de Versailles, Université Versailles-St Quentin, UMR CNRS 8180, 78035 Versailles, France.
authors.forename: Damien
authors.initials: D
authors.lastname: Aureau
authors.affiliation: Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSN-RES, SCA, LPMA, 91192 Gif-Sur-Yvette, France.
authors.forename: François-Xavier
authors.initials: FX
authors.lastname: Ouf
authors.affiliation: Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Wada
authors.affiliation: Institut Lavoisier de Versailles, Université Versailles-St Quentin, UMR CNRS 8180, 78035 Versailles, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Etcheberry
authors.affiliation: IMRAM, Tohoku University, Sendai 980-8577, Japan.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Ueda
authors.affiliation: Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cedex, France.|Extreme Light Infrastructure - Nuclear Physics (ELI-NP), "Horia Hulubei" National Institute for Physics and Nuclear Engineering, 30 Reactorului Street, RO-077125 Măgurele, Jud. Ilfov, Romania.
authors.forename: Catalin
authors.initials: C
authors.lastname: Miron