Preparation Of Copper-based Oxide/T-ZNOW Nanocomposites And Its Photocatalytic Property

Zinc Oxide (ZnO), n-type semiconductor, is widely used in air purification, sewage treatment, sterilization antibacterial and other fields, because of its excellent activity to decompose the pollutants. However, under irradiation condition, the photogenerated electrons and holes in a single tetrapod-like ZnO whisker (T-ZnOw) can easily recombination in a short time, and the wide band gap (3.37eV) limited its photocatalytic ability. In order to improve the photocatalytic activity of T-ZnOw, semiconductor compound method is used to modify whiskers surface. And this thesis contains the following aspects:1. With a simple chemical method, Cu2+can be reduced into cuprous oxide (CU2O) by using copper nitrate as a source of copper, poly vinyl chloride (PVP, Mw=3000) as surfactant, glucose (C6H12O6), hydrazine hydrate (N2H4?H2O) and ethylene glycol (EG) as the reducing agents. It is found that the surface of tetrepod-like ZnO whisker (T-ZnOw) is covered by lots of CU2O nanoparticles. The morphology of CU2O nanoparticles is changed with the changing of reducing agents, which lead to different photocatalytic activities of Cu2O/T-ZnOw nanocomposites. Moreover, the amount and shape of CU2O nanoparticles change with different Cu/Zn molar ratios (Cu/Zn MRs). The amount of CU2O nanoparticles increase with the increasing of Cu/Zn MR, and the photocatalytic property of the nanocomposite increases with increasing Cu/Zn MR when the Cu/Zn MR≤7.2%, while it become decreases when the Cu/Zn MR>7.2%. Similarly, the band gap of nanocomposties decreases with increasing Cu/Zn MR when the Cu/Zn MR<7.2%, while it increases when the Cu/Zn MR>7.2%. In addition, the composite photocatalyst also remained high photocatalytic activity after four recycles of photodegradation experiment, although the surface of the cubic CU2O particles is partially oxidized.2. The copper oxide (CuO) nanoparticles are successfully deposited on T-ZnOw surface by using copper nitrate as raw material, Polyethylene glycol (PEG, Mw=4000) as template and surfactant and sodium hydroxide as precipitating agent with low temperature chemical deposition method. The influences of different reaction temperature and Cu/Zn molar ratios (Cu/Zn MRs) on the amount and morphology of CuO nanoparticles are investigated and corresponding to the influence on the photocatalytic activities of the nanocomposites are also disscussed. It is found that when the reaction temperature is fixed at70℃, the amount of CuO nanoparticles increases with the increasing of Cu/Zn MR. And the photocatalytic activities of T-ZnOw for MB and MO solution is obviously increased by composited with CuO nanoparticles. The photocatalytic property of the nanocomposite increasing with the increase of Cu/Zn MR. When the Cu/Zn MR is fixed at2.4%, the morphology and amount of CuO nanoparticles is changed with the increase of reaction temperature. If the reaction temperature is higher than70℃or lower than60℃, it is not suitable for the fabrication of CuO nanoparticles, and the most suitable temperature of CuO nanoparticles is60-70℃, and all the CuO/T-ZnOw composites have an excellent photocatalytic activity both for the degradation of MB and MO solution.3. With low-temperature water bath, we used an environmental-friendly chemical method only use water as oxygen supplier and solvent without any OH" reagents to synthesis scaly-like CuO/T-ZnOw nanocomposite which is deposited on T-ZnOw surface in an orderly fashion. The impact of PEG400concentration and reaction time on the morphology and amount of CuO nanoparticles are investigated and analysis in detail, the influence of PEG400and reaction time on the photocatalytic property of the nanocomposites and the formation mechanism of scaly-like CuO nanoparticles is also characterized in this thesis. It is found that when the reaction time is fixed at180min, the amount of scaly-like CuO nanoparticles would increase and arranged more orderly with the increasing of PEG content, and the PEG400concentration of0.90mol/L is the most suitable condition for CuO crystal growth. When PEG400concentration<0.60mol/L, the photocatalytic property of nanocomposite increase with the increasing of PEG400concentration, while it decreases when further increasing the concentration of PEG400. Increasing the PEG400content would influence the emission peaks intensity of samples in PL spectra, which is similarly to the influence of composites photocatalytic activity. When the PEG400concentration is fixed at0.60mol/L, the morphology of scaly-like CuO nanoparticles deposited on T-ZnOw surface more intensively, and we analysis the formation mechanism of scaly-like CuO nanoparticles. In addition, the photocatalytic property of CuO/T-ZnOw nanocomposites increases with the increasing of reaction time.In this thesis, all the nanocomposites are synthesized by a relatively simple chemical synthesis method, which are operability and controllability, and thus can be applied in mass production. The obtained nanocomposites show effectively photodegradation for decomposing both methylene blue and methylene orange, and are expected to be applied in the organic pollutants treatment and air purification.