title: Low-frequency ultrasound induces oxygen vacancies formation and visible light absorption in TiO2 P-25 nanoparticles.
abstract: Low-frequency ultrasound (LFUS) irradiation induces morphological, optical and surface changes in the commercial nano-TiO(2)-based photocatalyst, Evonik-Degussa P-25. Low-temperature electron spin resonance (ESR) measurements performed on this material provided the first experimental evidence for the formation of oxygen vacancies (V(o)), which were also found responsible for the visible-light absorption. The V(o) surface defects might result from high-speed inter-particle collisions and shock waves generated by LFUS sonication impacting the TiO(2) particles. This is in contrast to a number of well-established technologies, where the formation of oxygen vacancies on the TiO(2) surface often requires harsh technological conditions and complicated procedures, such as annealing at high temperatures, radio-frequency-induced plasma or ion sputtering. Thus, this study reports for the first time the preparation of visible-light responsive TiO(2)-based photocatalysts by using a simple LFUS-based approach to induce oxygen vacancies at the nano-TiO(2) surface. These findings might open new avenues for synthesis of novel nano-TiO(2)-based photocatalysts capable of destroying water or airborne pollutants and microorganisms under visible light illumination.
authors.affiliation: SB-ISIC-GGEC, Station 6, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: Paula A
authors.initials: PA
authors.lastname: Osorio-Vargas
authors.forename: Cesar
authors.initials: C
authors.lastname: Pulgarin
authors.forename: Andrzej
authors.initials: A
authors.lastname: Sienkiewicz
authors.forename: Luis R
authors.initials: LR
authors.lastname: Pizzio
authors.forename: Mirta N
authors.initials: MN
authors.lastname: Blanco
authors.forename: Ricardo A
authors.initials: RA
authors.lastname: Torres-Palma
authors.forename: Christian
authors.initials: C
authors.lastname: Pétrier
authors.forename: Julián A
authors.initials: JA
authors.lastname: Rengifo-Herrera
mesh_terms: D000042:Absorption; D019220:High-Energy Shock Waves; D008027:Light; D008422:Materials Testing; D049329:Nanostructures / Q000737:chemistry* / Q000528:radiation effects*; D010100:Oxygen / Q000737:chemistry* / Q000528:radiation effects; D010316:Particle Size; D052638:Particulate Matter / Q000737:chemistry / Q000528:radiation effects; D013010:Sonication / Q000379:methods*; D014025:Titanium / Q000737:chemistry* / Q000528:radiation effects*
chemical_list: D052638:Particulate Matter; C009495:titanium dioxide; D014025:Titanium; D010100:Oxygen