Synthesis Of Ag₃PO₄-based Composites For Photocatalytic Degradation Of Organic Dyes

Recently, semiconductors act as photocatalysts for photocatalytic degradation of organic pollutant under visible light irradiation have attracted significant attention because of it’s a promising, environmental friendly, low cost, and high effective technology. Photocatalysts sensitive visible-light are urgently anticipated for oxidation of organic pollutant. The ability of this advanced oxidation technology have been widely utilized to remove organic pollutants.Silver orthophosphate (Ag3PO4) with band gap of 2.43eV have been explored as a novel photocatalyst exhibits extremely high photooxidative capabilities for the oxidation of water and the photodegradation of organic dyes under visible light illumination. Therefore, Ag3PO4 have a promising future in photocatalytic applications. The redox reaction potential of generated electron, rapid recombination of photoinduced generated electron-hole pairs, and the surface status of Ag3PO4 are considered as main factors that affect on its photocatalytic performances.In this thesis, the research target is to understand the surface structure properties, and the electronic effect on the photocatalysis are to improve the generation and separation of electron-hole pairs toward developing a high efficiency of the bare Ag3PO4 and Ag3PO4-based photocatalysts for environmental purifications. To achieve this target, two novel composites photocatalysts based on Ag3PO4 were successfully synthesized and investigated. This dissertation is divided into three chapters.Chapter 1, an overview of the synthesis of semiconductor photocatalyst and photocatalysis for environmental purification were first introduced. The synthesis and utilization of the bare Ag3PO4were discussed in details to provide useful information for developing efficiency of Ag3PO4 photocatalyst composite. In addition, the synthesis of the various structures of Ag3PO4 and strategies to achieve high efficiency of photocatalytic activities were also reported.Chapter 2, we report a novel fabrication photocatalyst of reduced graphene oxide magnetic nanoparticle RGO-Fe3O4 hybrid functionalized with Ag3PO4 for performance of photocatalytic reaction under visible light irradiation. The RGO-Fe3O4-Ag3PO4 composite was prepared and synthesized by a facile and effective electrostatic self-assembly method, the morphology and structures of products were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), UV-visible diffuse reflectance spectroscopy, fourier transform infrared (FTIR), photoluminescence (PL), electrochemical impedance spectroscopy (EIS). The presence of elements in the as synthesized nanoparticles were confirmed by the X-ray photoelectron spectroscopy analysis (XPS). The photocatalytic activity of RGO-Fe3O4-Ag3PO4 was evaluated by degradation of Rhodamine B dye under visible light irradiation to be nearly by 100% after short irradiation time with excellent recyclability and high efficiency of separation of electron-hole pairs during the photocatalytic reaction process.Chapter 3, a novel of visible light irradiation induced photodegradation of methyl orange dye over Fe3O4-Ag3PO4@AgI photocatalyst has been observed. The nanoparticles have been synthesized by a facile and effective in-situ ion exchange method and characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and UV-visible diffuse reflectance spectroscopy. The results shows that the magnetic nanoparticles and Agl molecules were immobilized on the surface of Ag3PO4 without the loss of photofunctionality and magnetic properties. The Fe3O4-Ag3PO4@AgI shows highest activity more than the Ag3PO4@AI and Ag3PO4. The photocatalytic activity of Fe3O4-Ag3PO4@AgI was evaluated by degradation of the organic dye nearly 100%after short irradiation time with a good recyclability.