Synthesis And Visible-light Photocatalytic Properties Of TiO₂Nanocomposites

Titanium dioxide(TiO2) is a kind of n-type metal-oxide semiconductor, receiving a wide study and great attractive application potential in the fields of photocatalytic reaction, sensors, photochemical synthesis, electrochromic, solar cells and photoinduced super-hydrophilicity. In the realm of photocatalysis, TiO2is widely applied to degrade a variety of organic pollutants and soil remediation for its biochemical inert, non-toxic, chemical stability and low cost, etc. However, pure TiO2usually can not meet practical needs. Therefore, the development of TiO2composites with other semiconductor or doping functional would be the mainstream in the research of TiO2. Meanwhile, it is also important to prepare nano-TiO2with special morphologies and large surface areas. In this paper, the research of TiO2composites is mainly concentrated in photocatalytic degradation organic pollution. It consists of material selection, preparation, characterization and theoretical analysis of the result in the experiments. The main contents are summarized as follows:1. The core-shell structured Fe2O3@TiO2nanocomposites were prepared via a heteroepitaxial growth route using the Fe2O3spindle as a hard template and TiF4as the precursor. The ratio of a-Fe2O3:TiO2in the nanocomposites can be tuned by etching the a-Fe2O3core via controlling the concentration of HC1and etching time. It is revealed that the optical response and photocatalytic performance of the core-shell a-Fe2O3@TiO2nanocomposites can be tuned by adjusting the molar ratio of2. The core-shell nanocomposite with an optimal molar ratio of7%for exhibits the best photocatalytic performance under visible light irradiation. It is shown that the Fe2O3/TiO2heteroj unction structure is responsible for the efficient visible-light photocatalytic activity.2. CuS-TiO2p-n junction nanocomposites were synthesized at room temperature, using TiO2hollow nanospheres as the basal body and thiolactic acid as coupling agent. The concentration of CuS can be tuned by the addition of Cu(NO3), leading to the enhancement of photoresponse. The morphology, microstructure and photocatalytic properties of the materials were tested by XRD, SEM, HRTEM and UV-vis. The experimental results showed that the coupled CuS could contribute to the enhancement of visible light response and visible light photocatalytic activity of the CuS-TiO2catalysts. The CuS-TiO2nanoparticles have better photocatalytic reactivity, the optimum content is2%, which would degrade about60%of the dye molecules.3. TiO2nanocrystals were prepared by a two-phase hydrothermal method, using tetrabutyl titanate and ferric oleate as the precursors. The nanomaterials were analyzed by XRD, HRTEM, UV-vis, FR-IR and PL, the result showed that Fe3+could be doped into TiO2nanocrystals by the hydrothermal method. The absorption edge of doped TiO2nanocrystals was extended to the visiblelight region. With the doping level increasing, the absorption intensity gradually increases.