Novel Visible-light-driven Ag, AgBr Supported Catalysts:Preparation And Properties

With the increasingly serious for global environmental pollution and energy crisis, environmental protection and sustainable development as a significant task have attracted much attention. Semiconductor photocatalysis technique is an efficient, low-cost and environmentally friendly method for the treatment of environment pollutants. But there are some shortcomings for most of the traditional photocatalyst, such as, low utilization of solar energy, the easy recombination of photoelectrons and holes and so on. Therefore, the development of novel visible-light-driven (VLD) photocatalysts is of great significance. In this thesis, Ag/AgBr/MoO3、 Ag/MoO3and Ag2MoO4/AgBr were successfully synthesized respectively. The photocatalytic activity of the samples was evaluated.The details are summarized as follows:1. Synthesis, characterization and excellent photocatalytic activity of Ag/AgBr/MoO3composite photocatalystAg/AgBr/MoO3composite photocatalyst with different Ag/AgBr dose were successfully synthesized via simple hydrothermal and precipitation method. The obtained products were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and UV-vis diffuse reflectance spectroscopy (DRS) in detail. The photocatalytic activity of the samples was evaluated by monitoring the degradation of rhodamine B (RhB) solution under visible-light irradiation. The results showed that Ag/AgBr/MoO3composite exhibited significantly enhanced photocatalytic activity, which was superior to that of pure MoO3and AgBr. We also investigated the factors affecting the photocatalytic properities. The enhanced photocatalytic activity could be attributed to the combined results of the relative large surface area, porosity structure and the efficient separation of photoinduced electron-hole pairs. Moreover, the composite was basically stable after recycle three times. The possible reaction mechanism was also discussed.2. preparation and catalytic properties of Ag/MoO3nanobeltMoO3nanobelt has been synthesized by a facile hydrothermal method, and followed by in-situ optical reduction of Ag+to produce Ag/MoO3nanocomposites. The as-synthesized Ag/MoO3composites were investigated by XRD, SEM, HRTEM, FT-IR and UV-vis DRS. SEM images showed that the as-synthesized Ag/MoO3composites were composed of orthorhombic a-MoO3nanobelts with good dispersion of cubic Ag nanoparticles on the surfaces. The catalytic activities of the Ag/MoO3composites were evaluated by using a model reaction based on the reduction process of4-nitrophenol (4-NP) into4-aminophenol (4-AP) in the presence of NaBH4as the reductant. The results indicated that all the belt-like nanocomposites exhibited excellent catalytic activities because the highly dispersed AgNPs were exposed on the surface of MoO3-NB, allowing effective contact with the reactants and catalytic. The Ag/MoO3-5.0%exhibited high catalytic activity. Furthermore, the adsorption of methylene blue (MB) and the photodegradation of rhodamine-B (RhB) were also investigated.3. Preparation and catalytic properties of Ag2MoO4/AgBrAg2MoO4/AgBr composites have been synthesized by a simple ion exchange-hydrothermal method. The obtained samples were characterized by XRD, SEM, FT-IR and UV-vis DRS. The photocatalytic activity of the Ag2MoO4/AgBr composites was evaluated by monitoring the degradation of RhB solution under solar-light irradiation. The antimicrobial property was also investigated. The results showed that Ag2MoO4/AgBr exhibited significantly enhanced photocatalytic activity and antimicrobial property compared to pure Ag2MoO4.