title: FeOx-TiO2 Film with Different Microstructures Leading to Femtosecond Transients with Different Properties: Biological Implications under Visible Light.
abstract: This study presents the first report addressing the effect of FeOx-TiO2 films microstructure on the transients detected by fast spectroscopy related to the long-range bacterial inactivation performance. The different fast kinetic femtosecond transient spectroscopy is reported for each FeOx+TiO2 microstructure. The lifetime of the short transient-species and the oxidative intermediate radicals generated under light were identified. Co-sputtered FeOx-TiO2 on polyethylene films presenting random distribution for both oxides were compared with sequentially sputtered FeOx/TiO2 films made up only by FeOx in the topmost layers. The ratio FeOx:TiO2 was optimized to attain the highest photo-conversion. By X-ray fluorescence, the Fe:Ti ration was found to be ~1.4 in the film bulk and by XPS-etching a ratio of 4:1 was found on the photocatalyst top-most layers. For co-sputtered FeOx-TiO2-PE films, the FeOx-TiO2 heterojunction led to electron injection from the FeOx to lower-lying TiO2 trapping states. The film optical properties, particle size, roughness, hydrophobic-hydrophilic shift and temporal evolution of the transient redox states were characterized in detail. Films with different microstructure led to different antibacterial activity. This suggests that the FeOx-TiO2-PE microstructure and not the position of the potential energy level of the semiconductors FeOx and TiO2 control the charge transfer under light irradiation.
authors.affiliation: Ecole Polytechnique Fédérale de Lausanne, EPFL-SB-ISIC-GPAO, Station 6, CH-1015 Lausanne, Switzerland.
authors.forename: Sami
authors.initials: S
authors.lastname: Rtimi
authors.affiliation: Ecole Polytechnique Fédérale de Lausanne, EPFL-SB-ISIC-GPAO, Station 6, CH-1015 Lausanne, Switzerland.
authors.forename: Cesar
authors.initials: C
authors.lastname: Pulgarin
authors.affiliation: N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, str. Kosygina 4, 119991 Moscow, Russia.|Moscow State University, Department of Chemistry, Leninskiye Gory 1-3, 119991, Moscow, Russian Federation, Russia.
authors.forename: Victor A
authors.initials: VA
authors.lastname: Nadtochenko
authors.affiliation: N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, str. Kosygina 4, 119991 Moscow, Russia.
authors.forename: Fedor E
authors.initials: FE
authors.lastname: Gostev
authors.affiliation: N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, str. Kosygina 4, 119991 Moscow, Russia.
authors.forename: Ivan V
authors.initials: IV
authors.lastname: Shelaev
authors.affiliation: Ecole Polytechnique Fédérale de Lausanne, EPFL-SB-ISIC-GPAO, Station 6, CH-1015 Lausanne, Switzerland.
authors.forename: John
authors.initials: J
authors.lastname: Kiwi