Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Photodegradation of Pollutants in Air: Enhanced Properties of Nano-TiO2 Prepared by Ultrasound | Nanoscale Res Lett 2009 4 97-105 DOI s11671-008-9208-3 NANO EXPRESS Photodegradation of Pollutants in Air Enhanced Properties of Nano-TiO2 Prepared by Ultrasound Giuseppe Cappelletti Silvia Ardizzone Claudia L. Bianchi Stefano Gialanella Alberto Naldoni Carlo Pirola Vittorio Ragaini Received 29 July 2008 Accepted 11 November 2008 Published online 25 November 2008 to the authors 2008 Abstract Nanocrystalline TiO2 samples were prepared by promoting the growth of a sol-gel precursor in the presence of water under continuous CW or pulsed PW ultrasound. All the samples turned out to be made of both anatase and brookite polymorphs. Pulsed US treatments determine an increase in the sample surface area and a decrease of the crystallite size that is also accompanied by a more ordered crystalline structure and the samples appear to be more regular and can be considered to contain a relatively low concentration of lattice defects. These features result in a lower recombination rate between electrons and holes and therefore in a good photocatalytic performance toward the degradation of NOx in air. The continuous mode induces instead the formation of surface defects two components are present in XPS Ti 2p3 2 region and consequently yields the best photocatalyst. The analysis of all the characterization data seems to suggest that the relevant parameter imposing the final features of the oxides is the ultrasound total energy per volume Etot V and not the acoustic intensity or the pulsed con-tinuous mode. G. Cappelletti El . Bianchi A. Naldoni C. Pirola V. Ragaini Department of Physical Chemistry and Electrochemistry University of Milan Via Golgi 19 20133 Milan Italy e-mail G. Cappelletti S. Ardizzone C. L. Bianchi A. Naldoni C. Pirola V. Ragaini Consorzio INStM Via Giusti 9 50121 Florence Italy S. Gialanella Department of Materials Engineering and Industrial Technologies University of Trento Via Mesiano 77 38050 Trento Italy .
