Monodispersed TiO2 Microspheres and TiO2 Nanoparticles by Sol-Gel Process for Photocatalytic Applications

• Main Authors: shiau-ting tzeng, 曾筱婷
• Other Authors: Rong Fuh Louh
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/36643356528542539039

碩士 === 逢甲大學 === 材料科學所 === 98 === Two major tasks are involved in this study by achieving (a) uniformly sized, monodispersed titanium oxide (TiO2) microspheres by sol-gel method and (b) the photocatalysis effect of our sol-gel synthesized TiO2 nanoparticles, as compared to the commercial TiO2 nanoparticles by Degussa GmbH (Model P25) in Germany, in photodecomposition of methyl blue dye under testing environment of UV illumination. In our sol-gel process, titanium(IV) isopropoxide (TTIP) was used as precursor, which was dissolved in ethylene glycol (EG) to obtain lower hydrolysis rate in order to prevent rapid agglomeration or precipitation of TiO2 fine particles out of the hydrolysis of titanium alkoxide. A fairly small amount of water (0.3~1.0 vol%) was added in acetone solvent, which was reacted with the EG solution with TTIP concentration (1~4 mM) to form submicron sized TiO2 microspheres in 180~200 nm range through the poly-condensation reaction. Such titania microspheres with uniform size and high sphericity, which can be used to form photonic crystal structure by rapid confined self-assembly process, were manifested by SEM and light-scattering particle size analyzer. Acetone solvent with small water content (0.75~2.25 vol%) was reacted with the EG solution with fixed TTIP concentration (1 mM) to produce TiO2 nanoparticles with desirable crystalline phase and better photocatalytic outcome by controlling reduced poly-condensation rates and various calcination temperature (400~ 700oC). In addition, the nucleation rate of primary particles can be controlled by using different filling speed of precursor (0.5~2.0 ml/min) into the acetone solution in the reaction tank. Under the XRD examination, the crystalline structure of our TiO2 nanoparticle specimen in a range of 40~80 nm is of anatase phase related to good photocatalytic performance. Photodecomposition efficiency of methyl blue dye was 63% by using the TiO2 particles, which were prepared with water content of 1.75 vol% and was calcined at 500oC. The higher calcination temperature (600oC) helped to reach a better photodecomposition efficiency (70%) for titania nanoparticles. Interestingly the maximal photodecomposition efficiency of our TiO2 nanoparticles out of optimized process parameter by selecting a slower filling speed of precursor (0.5 ml/min) was 82%, which far exceeds the efficiency (60%) out of commercial P25 powders.