TiO2晶型对Au/TiO2上光催化分解臭氧的影响

以不同晶型TiO2为载体,采用沉积-沉淀法制备了Au/TiO2光催化剂,并用紫外-可见漫反射光谱、X射线光电子能谱(XPS)和表面光电压谱(SPS)等手段进行了催化剂表征,详细考察了Ti O2晶型对Au/TiO2光催化分解臭氧活性的影响.结果表明,光催化分解臭氧的活性顺序为Au/P25>Au/Anatase>Au/Rutile,这与不同的单一Ti O2对光催化臭氧分解的活性顺序是一致的.但在TiO2上沉积金后,其对光催化臭氧的分解活性有了显著的提高.由催化剂的Au4fXPS分析发现,不同晶型Ti O2上的电荷向金簇迁移的能力有明显差异,加之载体本身对光催化臭氧分解活性不同,两者协同作用导致负载金催化剂光催化分解臭氧活性的不同.SPS信号强度与催化剂光催化活性有很好的对应关系,SPS信号越强,光生电子和空穴分离效率越高,光催化活性越好.

Effect of Crystal Form of TiO2 on Photocatalytic Decomposition of Gaseous Ozone over Au/TiO2

The Au/TiO2 photocatalysts were prepared by the deposition-precipitation method. Three different crystal forms of TiO2 were used as supports. The influence of crystal form of TiO2 on photocatalytic decomposition of gaseous ozone over Au/TiO2 was studied. The photocatalysts were characterized by ultraviolet-visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy (XPS), and surface photovoltage spectroscopy (SPS). The results showed that the photocatalytic activity of the catalysts was in the order Au/P25>Au/Anatase>Au/Rutile, in agreement with the order of the photocatalytic activity of pure TiO2. The photocatalytic activity of the catalysts increased obviously by loading Au. The results of Au 4f XPS showed that the ability of transferring electron from TiO2 to Au clusters was obviously different in three kinds of TiO2. The synergistic effect was responsible for the different activity of Au/TiO2. The SPS signals were consistent with photocatalytic activity: the stronger the SPS signal, the faster the separation rate of photoinduced electron-hole pairs, the higher the photocatalytic activity.