title: Coupling of narrow and wide band-gap semiconductors on uniform films active in bacterial disinfection under low intensity visible light: implications of the interfacial charge transfer (IFCT).
abstract: This study reports the design, preparation, testing and surface characterization of uniform films deposited by sputtering Ag and Ta on non-heat resistant polyester to evaluate the Escherichia coli inactivation by TaON, TaN/Ag, Ag and TaON/Ag polyester. Co-sputtering for 120 s Ta and Ag in the presence of N₂ and O₂ led to the faster E. coli inactivation by a TaON/Ag sample within ∼40 min under visible light irradiation. The deconvolution of TaON/Ag peaks obtained by X-ray photoelectron spectroscopy (XPS) allowed the assignment of the Ta₂O₅ and Ag-species. The shifts observed for the XPS peaks have been assigned to AgO to Ag₂O and Ag(0), and are a function of the applied sputtering times. The mechanism of interfacial charge transfer (IFCT) from the Ag₂O conduction band (cb) to the lower laying Ta₂O₅ (cb) is discussed suggesting a reaction mechanism. The optical absorption of the TaON and TaON/Ag samples found by diffuse reflectance spectroscopy (DRS) correlated well with the kinetics of E. coli inactivation. The TaON/Ag sample microstructure was characterized by contact angle (CA) and by atomic force microscopy (AFM). Self-cleaning of the TaON/Ag polyester after each disinfection cycle enabled repetitive E. coli inactivation.
authors.affiliation: Ecole Polytechnique Fédérale de Lausanne, EPFL-SB-ISIC-GPAO, Station 6, CH-1015 Lausanne, Switzerland. sami.rtimi@epfl.ch
authors.forename: S
authors.initials: S
authors.lastname: Rtimi
authors.forename: R
authors.initials: R
authors.lastname: Sanjines
authors.forename: C
authors.initials: C
authors.lastname: Pulgarin
authors.forename: A
authors.initials: A
authors.lastname: Houas
authors.forename: J-C
authors.initials: JC
authors.lastname: Lavanchy
authors.forename: J
authors.initials: J
authors.lastname: Kiwi
mesh_terms: D000042:Absorption; D004203:Disinfection / Q000379:methods*; D004563:Electrochemistry; D004926:Escherichia coli / Q000378:metabolism / Q000528:radiation effects; D007700:Kinetics; D008027:Light; D050296:Microbial Viability; D018625:Microscopy, Atomic Force; D046529:Microscopy, Electron, Transmission; D055095:Optics and Photonics; D056951:Photoelectron Spectroscopy; D011091:Polyesters / Q000737:chemistry; D012666:Semiconductors; D012834:Silver / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature; D013816:Thermodynamics; D013997:Time Factors; D014965:X-Rays
chemical_list: D011091:Polyesters; D012834:Silver
keywords: E. coli inactivation; Sputtering/co-sputtering; TaON/Ag; Visible light