Investigations Of Modification And Interfical Photoinduced Charge Separation Of Nanosized TiO₂

In this work, the nanosized TiO₂ was modified by transition metal doping, surfactant surface capping and dye sensitization methods, the as-prepared samples were characterized by modern testing methods, such as surface photovoltage spectrum (SPS) and photoluminescence (PL), and the influence mechanisms of modification were principally investigated.Nanosized TiO₂ doped with Zn was prepared by a sol-hydrothermal process. The influences of different calcination temperature and Zn content on the TiO₂ crystal structure and surface structure were studied and the effect of Zn-doping on photoinduced charge separation and photocatalytic activity were principally investigated. The results show that Zn can slightly promote the TiO₂ phase transiton from anatase to rutile, the appropriate calcinations temperature and Zn-doping content can improve the photoindcued charge separation and surface state of TiO₂, which are responsible for the enhancement of TiO₂ photocatalytic performance. Zn-doping can also increase photocatalytic activity of TiO₂ film. In additon, the added sodium dodecylbenzenesulfonate (DBS) in preparation process of film can enlarge film surface.The nanosized TiO₂ capped with DBS and cethyltrimethylammonium bromide (CTAB) were prepared, respectively. The proper modification conditions were explored, and capping mechanisms were discussed in detail. The influences of modification on photoinduced charge transfer and photocatalytic performance were investigated, in principle. The results show that DBS and CTAB groups can cap TiO₂ surface under conditions of appropriate pH value and surfactant amounts. The capping mechansims of DBS and CTAB are very different, the former is close related to electrostatic attraction, and the latter is not only related to electrostatic attraction, but to hydrogen bond. The appropriate amounts of two surfactant groups are in the range of 1 % 3 % compared to TiO₂ mass, and the optimal amount is about 2 %, indicating that there is a certain number of surface active site on a TiO₂ particle. In addition, the buffer system can influence the capping effect.The photocatalytic activity of TiO₂ increases after its surface is capped by DBS...