Low-frequency ultrasound induces oxygen vacancies formation and visible light absorption in TiO2 P-25 nanoparticles |
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Authors: | Osorio-Vargas Paula A Pulgarin Cesar Sienkiewicz Andrzej Pizzio Luis R Blanco Mirta N Torres-Palma Ricardo A Pétrier Christian Rengifo-Herrera Julián A |
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Institution: | a SB-ISIC-GGEC, Station 6, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland b SB-IPMC-LPMC, Station 3, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland c Centro de Investigación y Desarrollo en Ciencias Aplicadas “Dr. J.J. Ronco”, CINDECA, Departamento de Química, Facultad de Ciencias Exactas, UNLP-CCT, La Plata, CONICET, Calle 47 No. 257, 1900 La Plata, Buenos Aires, Argentina d Instituto de Química, Facultad de Ciencias Naturales y Exactas, Universidad de Antioquia, A.A. 1226, Medellín, Colombia e Laboratoire de Rhéologie et Procédés, Université Joseph Fourier, BP 53, 38041 Grenoble, France |
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Abstract: | Low-frequency ultrasound (LFUS) irradiation induces morphological, optical and surface changes in the commercial nano-TiO2-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 (Vo), which were also found responsible for the visible-light absorption. The Vo surface defects might result from high-speed inter-particle collisions and shock waves generated by LFUS sonication impacting the TiO2 particles. This is in contrast to a number of well-established technologies, where the formation of oxygen vacancies on the TiO2 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 TiO2-based photocatalysts by using a simple LFUS-based approach to induce oxygen vacancies at the nano-TiO2 surface. These findings might open new avenues for synthesis of novel nano-TiO2-based photocatalysts capable of destroying water or airborne pollutants and microorganisms under visible light illumination. |
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Keywords: | Visible-light responsive TiO2 Low-frequency ultrasound Oxygen vacancies |
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