Preparation And Photoluminescence, Photocatalytic Activities Of ZnO-based Composite Materials

In recent years, the development of industry has caused increasingly serious problem of environmental pollution, especially industrial wastewater pollution, which has seriously affected people’s health and life quality, ZnO semiconductor material is an ideal catalyst for photodegradation of industrial wastewater, but the low quantum yield, narrow spectral response range severely limits its application and development. This paper combined silver, palladium and gold nanoparticles with small-sized semiconductor ZnO to form Ag-ZnO, Pd-ZnO and Au-ZnO composite materials. By using noble metal nanoparticles as an electron transfer medium, while stabilizing properties of ZnO nano-shells, especially small size effect, UV response, etc., we collaborate noble metal nanoparticles and ZnO semiconductor to achieve the separation of electron-hole pairs, thereby improving the catalytic properties of ZnO. By changing the reaction conditions we prepared a series of high stability, high catalytic activity-based composite materials, achieved its catalytic performance to the degradation of organic pollutants under sunlight; we explored the metal doping amount, the dispersion of particles, calcination temperature and other factors impact on the sample luminescence properties and photocatalytic properties, selected the most active catalyst; we also discussed the catalytic mechanism of photocatalytic reaction, laying an theoretical and experimental basis for the design of such catalysts. The main findings are as follows:1. ZnO nanoparticles were prepared by solvothermal method, the samples have been characterized by XRD, TEM, PL and UV-vis spectrum. The results showed that our sample had good purity and crystallinity, two distinct peaks in the PL light emission wavelength between 380 nm and 450-650 nm have detected, besides, the sample had a certain catalytic effect to the degradation of Rhodamine B under visible light.2. Ag-ZnO nanocomposite was prepared by solvothermal method, the structure and nature of the obtained sample has been explored. The results show that Ag-ZnO has good crystallinity and dispersion degree, compared with pure zinc oxide, the nanocomposite showed decreased PL emission peak and enhanced catalytic degradation to Rhodamine B.3. Pd-ZnO composite was prepared by solvothermal method, the structure and nature of the obtained sample has been explored. The results showed that the samples is hexagonal pore structure, Pd nanoparticles was uniformly dispersed in the zinc oxide surface, the composite revealed higher purity and good crystal properties, besides, compared with pure zinc oxide, its luminescent properties and catalytic properties have changed.4. Honeycomb and porous columnar Au-ZnO composites had prepared by hydrothermal synthesis, they have good purity and crystalline properties, compared with pure zinc oxide, both of the samples showed reduced PL peaks and enhanced catalytic activity of rhodamine B, besides, owing to the higher gold content and surface area of honeycomb samples, it had the highest catalytic activity to RhB degradation.5. The photocatalytic mechanisms of the three composites were explored respectively, besides, the possible mechanism schematic were given, laying an theoretical foundation for these researches.