Fabrication And Characterization Of ZnO-Base Photocatalytical Materials

In the21st century, the globle environmental pollution and energy crisis is becoming more and more serious, and they have been serious affected the survival and development to human being. Photocatalytic oxidation technology is considered to be one of the most effective ways to solve this difficult problem. Photocatalytic technology has become an international hot spot in the field of catalysis due to low consumption easy operation, no secondary pollution, etc. ZnO, as a kind of low efficient non-toxic easy preparation of photocatalyst, has received extensive attention in the world. In this thesis, we focus on how to improve photocatalytic efficiency and effectively utilize solar energy as well as the use of some of the bad environment for ZnO materials, then we fabricated ZnO-base binary, ternary composite photocatalyst and some InGaN nano materials.Finally, the morphology, crystal structure, surface physical chemistry properties and photocatalytic behavior were characterized, the causes of enhance photocatalytic efficiency were discussed. Some new and interesting results are as following:1. The silver nanoparticles, nanocubes and nanowires were synthesized via microwave condensing reflux method. The different morphologies of silver nano-products were obtained through changing the concentration of Na2S, heating power, reaction time, and surfactant concentration. The results show that the silver nanoproducts have gone through a spherical-cube-linear evolution in the morphology with gradually increasing Na2S concentration from0to1to1.5mM. In addition, the effect of S2" on the morphology and the formation mechanism of silver nanoproducts are further discussed in this study.2. Mono-dispersed ZnO microspheres were synthesized through ultrasonic irradiation using zinc acetate, and triethanolamine. The results indicate that the the products was changed from Zn5(OH)8Ac2·2H2O to ZnO nanoparticles, simultaneously, ZnO nanoparticles assemble into spherical structure under ultrasonic irradiation with the increase of reactin time. UV-vis absorption measurement of as-prepared products at different stages shows that the absorption peaks became sharper and blue-shifted from422to364nm with the change of composition and morphology. Photoluminescence (PL) measurement show that the intensity of the UV emission increased with the increase of reaction time. Photocatalytic tests show that photocatalytic activity will decrease with increasing for size of ZnO particles, which may be related to the size and crystallinity of ZnO particles.3. Novel worm-like Ag/ZnO core-shell heterostructural composites were fabricated using a two-step chemical method. As-prepared silver nanowires were soaked in a solution of zinc acetate and triethanolamine to form worm-like Ag/ZnO core-shell composites under ultrasonic irradiation. The results show that the core-shell composites are composed of single crystal Ag nanowires served as the core, on which dense ZnO particles grow as the shell. The PL intensity of Ag/ZnO heterostructural composites varies and appears the minimum intensity for the sample prepared with Ag of2.8at.%. Moreover, photocatalytic tests show that the Ag/ZnO composites exhibit higher photocatalytic activity compared to pure ZnO particles.4. One-dimensional In2O3/ZnO/Ag heteroarchitectures with high visible-light photocatalytic activity have been successfully obtained by a simple combination of solvothermal process and annealing. The results revealed that the Ag nanowires were encapsulated by In2O3and ZnO nanostructures. By compared with Ag, ZnO/Ag, In2O3/Ag and In2O3/ZnO, the obtained In2O3/ZnO/Ag heteroarchitectures showed strongest the visible-light photocatalytic activity to degrade rhodamine B (RB). With the increase of Ag nanowires, the PL intensity of In2O3/ZnO/Ag heteroarchitectures first decrease and then increase, however, for In2O3/ZnO/Ag heteroarchitectures with higher Ag content (3.8wt%), an even better performance in MB photodegradation was attained.5. Different morphologies of InxGa1-xN nanomaterials were prepared upon Si substrates by APCVD. The results shown that all samples were wurtzite structure, however, the morphology changed from flower to pagoda with the effect of Au catalyst; with the inceeaseing of In content, the intensity of PL for InxGa1-xN nano-crystals increases and blue light zone appears. The pagoda InxGa1-xN show best photocatalytic efficency to degrade acid orange, and has highest efficiency for pH at3.