| With the development of morden industry and increasing consumption of the non-renewable resources about coal and oil, the globe environment and energy problems become more seriously. Many pollutants such as nitric oxide, sulfur oxide and organic waste were discharged into the air, soil and water which cause great damge to the environment. Solar energy as a green and renewable energy attracts more people’s concern. It is a big challage to improve the efficiency of the soalr energy. Semiconductor photocatalytic technology has been believed a environment friendly, low cost and high-efficiency technology. It has been applied in degeradion of toxic pollutants and energy translation. ZnGa2O4photocatalysts consisting p-block metal ions with d10configuration not only have been wildely used in the field of light-sensitive material, but also have been proved a great photocatalytic performance in degradation of benzene and MO and reduction of CO2. Conventional synethetic methods of ZnGa2O4materials include solid state method, hydrothermal route and CVD etc, which have many shortcomings such as long preparation time, irregular morphology, poor dispersion and seriously aggregated. Microwave hydrothermal synthesis is a green technology which has short synthesis period and accurate parameter control of temperature and pressure. The repeatability of experiment and production yield of prduct can be greatly improved through the method. Herein, uniform and highly dispersed nanoparticles with outstanding photocatalytic perfermance were synthesized by microwave hydrothermal homogeneous precipitation and ion exchange ways. Furthermore, utilizing γ-Ga2O3nanoflower as template ZnGa2O4nanoflower was successly synthesized. The photocatalytic activity is evaluated by the photocatalytic degradation of methyl orange and the splitting of water into hydrogen. Three aspects investigations were carried out in this dessertaton:(1) Monodisperse ZnGa2O4nanoparticles were obtained using microwave hydrothermal-homogeneous precipitation method with CTAB assisted at140℃. Synthetic temperature, surfactant, and calcination temperature have been studied on the formation of ZnGa2O4. Morphology of the obtained ZnGa2O4nanomaterials was characterized by scanning electron microscopy. Photoluminescence spectra (PL) of the samples were given to explain the recombination of photo-induced electrons and holes. Energy dispersive spectrometer was used to determine the elemental composition of the sample. Powder X-ray diffraction data were collected to analyze the cryst allographic phase of the samples. UV-vis diffuse reflectance spectra were recorded and transformed to the absorption spectra. It is concluded that the surfactant, calcinations tand synthesis temperature would have a great impact on the monopoly and efficiency of the electrons and holes.(2) Using microwave hydrothermal-ion exchange method, the ZnGa2O4nanomaterials synthesised with different ratio of Zn and Ga, different types of precursor and different synthetic temperature were studied. Water splitting were carried out over ZnGa2O4photocatalyst synthesised with GaOOH at180℃accompanying with the investigation on the effect of different types of sacrifice agent. A new way for making uniform and highly dispersed nanoparticles with outstanding photocatalytic perfoemace ZnGa2O4particles were-exploited. ZnGa2O4photocatalyst synthesised with GaOOH at180℃show a highly photocatalytic activity in degradation of methyl orange and splitting of water into H2. Especially, in the splitting of water into hydrogen after8h, the amount of H2generated is5times as the catalyst obtained by solid state method and1.5times as P25.(3) Uniform y-Ga2O3nanoflower with more petal were obtained through the reaction of Ga(NO3)3and ethanediamine with the suitable ratio of H2O. Comparing with conventional hydrothermal route, the y-Ga2O3product were more uniform, and less ethanediamine were needed. Utilizing γ-Ga2O3nanoflower at appropriate pH as template, ZnGa2O4nanoflower was successly synthesized. |
PDF Full Text Request