Surface Modification Of T-Znow And Its Photocatalytic Property

Due to their ability to decompose organic pollutants, semiconducting photocatalysts are widely used in some areas, such as disinfection, sewage treatment and air purification. Among all the semiconducting photocatalysts, ZnO is the one of the most widely used materials. However, its photocatalytic ability is limited by its relatively large band gap of 3.2 eV. In order to improve the photocatalytic ability of ZnO, noble metal deposition and semiconductor coupling are used. And this thesis consists of three following aspects:1. Under the condition of ultraviolet (UV) irradiation, Ag+ can be reduced into Ag0 by using polyethylene glycol (PEG) as solvent, protective agent and reduction agent. It is found the obtained Ag0 would be deposited on the tetrapod-like ZnO whisker (T-ZnOw) as nanoparticles. Moreover, the amount and shape of these nanoparticles change with different Ag/Zn molar ratios (MRs) and PEG concentrations, leading to different photocatalytic properties of the Ag/T-ZnOw nanocomposites. Specifically, the amount of Ag nanoparticles increases with increasing Ag/Zn MR, while increasing PEG content would reduce the mean particle size of Ag and the band gap of the nanocomposite. The photocatalytic property of the nanocomposite increases with increasing Ag/Zn MR when the Ag/Zn<14.4%, while it decreases when the Ag/Zn=14.4%. Similarly, The photocatalytic property of the nanocomposite increases with increasing PEG content when the PEG≤0.08 mol/L, while it decreases when the PEG>0.08 mol/L.2. CuO nanoleaflets or nanoneddles are successfully deposited on the surface of T-ZnOw by using AgN03 as raw material and PEG as solvent, template and protective agent under the condition of UV irradiation and low-temperature water bath. The influences of different Cu/Zn MRs and PEG concentrations on the morphology and amount of CuO nanoparticles are investigated and corresponding influence on the photocatalytic property of the nanocomposites are also characterized. It is found that when the PEG concentration is fixed at 0.01 mol/L, the CuO exist as nanoleaflet and its amount increases with increasing Cu/Zn MR. When the Cu/Zn≤9.6%, the photocatalytic property of the nanocomposite increasing with increasing Cu/Zn MR, while it decreases when Cu/Zn>9.6%. When the Cu/Zn MR are fixed at 2.4%, the amount of CuO would increase with increasing PEG content, while the size of CuO nanoparticles will be reduced. When the PEG concentration is larger than 0.04 mol/L, the CuO exists as nanoneddles. The photocatalytic properties of the nanocomposites increase with increasing PEG concentration when the content of PEG is smaller or equal to 0.06 mol/L and further increasing PEG concentration decreases the photocatalytic property of the nanocomposite.3. CU2O nanocubes are successfully deposited on the surface of T-ZnOw by using AgNO3 as raw material, ethylene glycol (EG) as solvent and polyvinyl chloride (PVP) as protective agent under the condition 180℃. The influence of Cu/Zn MR and PVP concentration on the morphology and amount of CU2O nanocubes are investigated and corresponding influence on the photocatalytic properties of the nanocomposites are also investigated. It is found that when the weight of PVP is fixed at 0.06 g, the CU2O exist as nanocube and its amount increases with increasing Cu/Zn MR, while its size decrease with increasing Cu/Zn MR. When the Cu/Zn≤7.2%, the photocatalytic property of the nanocomposite increase with increasing Cu/Zn MR. However, further increasing Cu/Zn MR leads to decreased photocatalytic property. When the weight of PVP≤0.08 g, the amount of Cu2O nanocubes increases with increasing weight of PVP. When the weight of PVP>0.08, the nanocomposite exhibits relatively inferior photocatalytic property. What's more, Cu2O exist as nanospheres, indicating the effect of PVP on the shape of the nanoparticles.In this thesis, all the nanocomposites are synthesized by a one step method. So, it has the advantage easy and cheap, and thus can be applied in mass production. The obtained nanocomposites are very effective in decomposing methylene orange and can be widely used in sewage treatment and air purification.