Synthesis of Hollow TiO2 Spheres and Applications to Photocatalysis and Dye-Sensitized Solar Cells

• Main Authors: Po-Sung Chao, 趙伯崧
• Other Authors: 曾文甲
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/86465761658773546703

碩士 === 國立中興大學 === 材料科學與工程學系所 === 99 === This research uses template-implantation method for synthesis of TiO2 hollow microspheres. The TiO2 hollow microspheres were prepared by using heptane as a reactive solvent, TiCl4 as a TiO2 precursor, and organic microspheres as a template. Ti4+ ions were found to implant into the underlying surface of organic template to form a core-shell structure, leading to formation of hollow microspheres after calcination to remove the organic microspheres. The reaction temperature, calcination temperature, and TiCl4 content have been changed to observe surface microstructure, crystalline phase and specific surface area of the microspheres by TEM, FE-SEM, XRD, DLS and BET. In addition, use of the TiO2 hollow microspheres in photocatalysis and dye-sensitized solar cell was compared with that of commercial TiO2 nanopowder (Degussa P25). From FE-SEM and TEM observation, particle size of the TiO2 hollow microspheres is about 700 micrometre. From XRD results, crystal phase transforms from rutile phase at temperatures above 650oC. When calcination temperature was increased from 450 oC to 750 oC, crystallite size grows from 82nm to 137nm,rutile percentage increased from 7 to 100%, and specific surface area reduced from 43 to 21m2/g. When reaction temperature was increased from 55 oC to 90 oC, rutile size is no change while the rutile fraction increased from 15 to 80% and the specific surface area reduced from 36 to 8m2/g. In the methylene blue photocatalysis experiment, due to the reduction in specific surface area and the increased rutile percent, photocatalysis rate constant is reduced from 0.058min-1 to 0.02min-1. The TiO2 hollow microspheres have the same specific surface area and crystal phase with that of the P25 yields the same photocatalytic efficiency. In dye-sensitized solar cell test, hollow sphere photo electrode has 0.001g unit area, and P25 photo electrode has 0.003g unit area, therefore adsorbed dye amount is different. Hollow sphere photo electrode’s photo-electric efficiency is low compared with that of P25. If photo-electric efficiency take photo-electric efficiency per a unit of weight, hollow sphere photo electrode has hight photo-electric efficiency per a unit of weight.