Au掺杂方式对锐钛矿TiO2光催化性能的影响

结合超临界乙醇干燥技术, 采用沉积-沉淀(DP)和共沉淀(CP)法分别制备了具有单一锐钛矿晶相的Au/TiO2和Au(0.2%, 原子分数)-TiO2光催化剂, 通过XRD、BET、TEM、XPS和Raman手段表征样品中Au的掺杂形态, 以光催化降解甲基橙为模型反应考察了样品的光催化活性. 结果表明, DP法制备的Au/TiO2在110 ℃干燥处理后, 表面存在的Au3+能有效地促进锐钛矿TiO2光催化性能, 其一级反应速率常数比纯锐钛矿TiO2提高了3.2倍, 比商用光催化剂Degussa-P25提高了4.1倍, 而当Au3+被还原为Au0后光催化活性下降. 用CP法制备的Au-TiO2并没有较大地提高锐钛矿TiO2光催化性能, 在焙烧温度达到800 ℃时, Au向表面迁移聚集, 造成锐钛矿TiO2晶格氧空位和缺陷位增加, 使光催化活性下降.

Effect of Gold Doping on the Photocatalytic Activity of the Anatase TiO2

Combined with supercritical ethanol drying, anatase Au/TiO2 and Au-TiO2 with 0.2%(atom fraction) Au content were synthesized by the deposition-precipitation (DP) and the coprecipitation (CP) respectively, and characterized with XRD, BET, Raman, XPS, and TEM. The activity was investigated using the photocatalytical degradation of methyl orange as probe. The results showed that the Au/TiO2 dried at 110 ℃ had a very high photocatalytic activity, the first-order reaction rate constans were 3.2 and 4.1 times higher than those of pure TiO2 and commercial Degussa-P25 photocatalyst respectively. The activity of Au/TiO2 decreased after thermal treatment or reduction in hydrogen due to the reduction of Au3+. A suitable amount of Au3+ on the surface of TiO2 as a trap for photogenerated electron can be beneficial to improving the efficiency of the photocatalytic oxidation process. The Au-TiO2 did not improve the photocatalytic activity of TiO2. The sample with higher crystallization degree after thermal treatment had the higher activity. But when the sample was treated in 800 ℃, the Au would be reduced and moved from the bulk to the surface of TiO2, which resulted in the increase of lattice oxygen vacancy and the decrease of activity.