Study On Preparation Of Cadmium Germanate Micro-nano Material And Its Photocatalytic Properties

In recent years, environmental pollution has becoming increasingly serious, which calls for urgent solution in the world. Photocatalytic oxidation takes solar energy as light source and the ambient oxygen as oxygen source to degrade environmental pollutants with the help of photocatalysts. Photocatalytic oxidation gets great attention for its low energy consumption and environmental-friendly. TiO2material is the most mature photocatalyst, and TiO2-based study has been carried out in depth for decades. Nowadays, the development of new materials used as photocatalysts is becoming an alternative approach in the field of photocatalytic oxidation. Researchers paid much attention to ternary oxides for their unique properties and potential applications. A series of studies have shown that ternary oxides are usually more complex in geometry and band structure, demonstrating different optical, electrical and thermal properties compared with conventional semiconductor materials. Cd2Ge2O6is a new type of ternary oxide, and the related research remains rare. Thus, we take Cd2Ge2O6as reseach object. Spindle-like Cd2Ge2O6assemblies were synthesized by a hydrothermal route, followed by series of characterization. Photocatalytic properties of the as prepared Cd2Ge2O6was evaluated via the decomposition of gaseous toluene, gaseous benzene and4-chlorophenol solution respectively. In this dissertation, our investigations were carried out as follows:(1) Spindle-like Cd2Ge2O6micro-nano material was prepared through a hydrothermal way. It was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and some other techniques to study the morphology and composition of the Cd2Ge2O6sample. Pore structure and surface area were tested through nitrogen adsorption and desorption method. Optical property was also examined by UV-vis diffuse reflectance spectroscopy (DRS).(2) In the DRS spectra, the Cd2Ge2O6sample showed obvious response to ultraviolet light. Therefore, UV lamp was applied to simulation of light source to evaluate its photocatalytic properties. With the help of in-situ infrared spectra technology, the photocatalytic behaviors in degradations of gaseous toluene and gaseous benzene were investigated. In the photocatalytic degradation of toluene, benzaldehyde was found to be intermediate, and CO2and CO were the final products. The degradation efficiency was as high as88.3%after10h. Final products turned to be H2O, CO2and CO in the photocatalytic degradation of benzene, with a degradation efficiency of62.1%after10h. We evaluated the stability of the catalyst through the comparison of IR spectra of fresh and used Cd2Ge2O6.(3) The photodegradation of4-chlorophenol was also performed to further evaluate the photocatalytic property of the Cd2Ge2O6sample. Results showed that degradation efficiency reached75%after5h photoreaction. An additional experiment was also performed through the fluorescence method to examine the ability of light-excited Cd2Ge2O6inducing the formation of hydroxyl radicals, which is the key reactive species. Results showed a high ability of light-excited Cd2Ge2O6inducing the formation of hydroxyl radicals, indicating the strong oxidizing capacity of photo-excited holes.