Evolution of Textural, Structural and Morphological Properties of Ag/TiO 2 Nanocomposites Tailored by Temperature
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1174-V06-25
Evolution of Textural, Structural and Morphological Properties of Ag/TiO2 Nanocomposites Tailored by Temperature Marcelo M. Viana and Nelcy D. S. Mohallem Laboratory of Nanostructured Materials, Chemistry Department, UFMG, 31270-901 Belo Horizonte, Brazil ABSTRACT TiO2 is a promising material for use in environmental purification due to its strong oxidizing power, photoinduced hydrophilicity, non-toxicity and long-term photostability. Nanocomposites formed by silver dispersed in titania matrix have their application quality improved since silver particles can act in the electronic structure of the titania. In this work, titanium isopropoxide and silver nitrate solution was used as starting of Ag/TiO2 nanocomposites. After irradiation and gelification at room temperature, this material was dried and calcined at various temperatures up to 1100 ºC. The nanocomposites were characterized to investigate the structural evolution of the nanoparticles and the dependence of crystallite size with the calcination temperature. INTRODUCTION TiO2 nanometric systems present great scientific and technological application in photocatalysis [1-4], sterilization, superhydrophilicity [5], superconductivity [7], gas sensors [6], among others. On the other hand, the silver has being used as a bactericidal material since the antiquity and in the current days nanoparticulate silver is used to impregnate commercial products, adding value to the final product [8]. Ag/TiO2 nanocomposite has its potentiality of application raised when compared with the components in its simple form, because silver particles act as electron traps aiding electron– hole separation, promoting the photocatalyze in the visible region [9]. Ag/TiO2 nanostructured have been confectioned for diverse methods of synthesis as hydrothermal process, used in the production of nanotubes and nanosheets [10], spray pyrolysis producing spherical nanoparticles [11], beyond methods that generate core-shell nanostructure in nanoparticles [12], nanowire [13] and nanofibers [14]. This nanocomposite has bactericide properties [15], can be transformed of super hydrophobic in super hydrophilic material [5], can be used in the solar energy conversion [3], has anticorrosive [16] and photochromic [17] properties. In this work, Ag/TiO2 nanocomposites were prepared by sol-gel process. After irradiation and gelification at room temperature, these materials were dried and calcined at various temperatures. The evolution of the nanoparticles with the calcinations temperature was studied. EXPERIMENT A solution with titanium isopropoxide (IV) (Ti(OCH(CH3)2)4) 97% (Aldrich) diluted in isopropyl alcohol 99.5% (Merck) mixed with acetic acid was magnetically stirred for 1 hour. A solution of silver nitrate diluted in acetonitrile was added to the starting solution, with Ag:Ti ratio of 1:6. This solution was conditioned in a chamber and submitted
to stirring and irradiation by ultraviolet UV-C (254 nm) for 12 hours, using two fluorescent light bulbs of mercury (Girardi RSE20B) of 15 W each
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