Synthesis Of TiO₂ Nanoparticles With Different Crystal Phases And Deposition Of Gold

As a broad forbidden-band semiconductor, titania (TiO2) has significant applications in solar energy conversion, photocatalysis and photoelectronic devices. Therefore, the preparation methodology, catalysis mechanism and physicochemical properties of TiO2 have attracted a lot attention by many researchers. Without any template, TiO2 nanoparticles with different crystal phases and morphologies have been synthesized by improving the preparation methods and optimizing the preparation conditions. The effects of crystal phase and surface modification on the photocatalytic activities of TiO2 nanoparticles are tested and analyzed.By controlling the concentration of acid peptizator, highly dispersed rutile TiO2 (R-TiO2) shuttle-like nanorods, TiO2 nanoparticles with different ratios of rutile phase and anatase phase (R/A-TiO2), and anatase TiO2 (A-TiO2) nanoparticles are prepared through a low-temperature sol-gel phase transfer technique. Meanwhile, Au nanoparticles are in situ deposited on TiO2 nanoparticles by an optical radiation of Au3+ solution. Effect of Au-TiO2 nanoparticles on the degradation rate of Methylene blue is tested to investigate the influences of crystal phase and morphology of TiO2 nanoparticles on the photocatalytic activities of Au-TiO2 nanocomposites. It is found that the photocatalytic activity of TiO2 can be obviously enhanced by surface decoration of Au nanoparticles. The photocatalytic activity of the prepared materials can be ranked as: Au-R/A-TiO2(with more anatase phase)> A-Au-TiO2> Au-R/A-TiO2 (with more rutile phase)> R-Au-TiO2. With 0.08 mol% Au decorated, the photocatalytic efficiency of Au-R/A-TiO2 (with more rutile phase) can be as high as 97.8%, which is an obvious improvement as compared with that of R/A-TiO2 (with more rutile phase) (70.77%).(001)-rich TiO2 with high photocatalytic activity are also prepared by a solvothermal method, using butyl phthalate, isoproponal and HF as raw materials. The effects of raw material amount, temperature and reaction time on the preparation and photocatalytic activity of (001)-rich TiO2 are studied. Research indicates that in a 30-ml hydrothermal reactor charged with butyl phthalate concentration of 0.15 g/ml and 0.6 ml of 40% HF, (001)-rich TiO2 can be obtained at 180 oC for 24 h. Notably, this (001)-rich TiO2 displays a high photocatalytic activity. Deposited with Au nanoparticles, the photocatalytic efficiency of TiO2 has improved from 38.68% to 65.82% with UV radiafion for 90 min.