Photocatalytic activity of SiO2-TiO2 Nanoparticles Prepared by Hydrothermal Process

초록

[SiO2]x[TiO2]1-x(x=0.1, 0.2, 0.3, 0.4) powders were prepared with various ethanol content by hydrothermal process at 2500C. Titanium isopropoxide (TTIP) and tetraethylorthosilicate (TEOS) were used as precursors of Ti and Si, respectively. Isopropanol and ethanol were employed as solvents, and nitric acid is used as a catalyst for sol-gel reaction. In this work, the phase formation, particle size, reactive surface area and morphologies of TiO2 were investigated varying the SiO2 composition and the ethanol content. In order to study the effect of ethanol on the particle sizes of TiO2, the exess amount of ethanol(ethanol: H2O; alkoxide=120: 100: 1, mole ratio) were introduced, and the reaction products were compared with that of the conventional hydrothermal synthesis occurring at aqueous solution(ethanol: H2O; alkoxide=1: 150: 1, mole ratio). The microstructure and photocatalytic activity of the prepared SiO2-TiO2 nanoparticles were characterized by XRD, SEM, Raman, BET and UV-Visible Spectroscopic techniques. It was confirmed that the major phase for all the samples was anatase. As the increase of silica contented from 0.1 to 0.4 molar ratio, the particle size of SiO2 decreased from 12.4 to 7.4 nm. Also, it was observed that the larger the surface area of composite powders were generally increased with the increase of SiO2 addition. We believe that the higher BET surface area of composite powder are due to the presence of SiO2 in the TiO2 grain boundary which inhibits crystallite growth of TiO2. The particle size of 0.3SiO2-0.7TiO2 powders prepared under reverse micelle circumstance was about 7.7 nm, while that of particles size prepared with conventional hydrothermal process was 11.5 nm. The photocatalytic activity of this composite powders(0.3SiO2-0.7TiO2) under excess ethanol was 1.5 times higher than that of pure TiO2 in decomposition 1,4-dichlorobenzene.