The Preparation Of Silver Halide Visible Light Catalyst And Its Catalytic Performance

With the development of the global industrialization, severer environmental pollution has been encountered. Photocatalytic technology, as a typical representative of green chemistry, attracts increasingly interest. There are many methods for disposing pollutant, among which the multiphase photocatalysis has been widely used. Photocatalyst has prospect of application in solving the problem of energy shortage, environment pollution and global warming. However, the traditional photocatalyst TiO2requires ultraviolet (UV) light (λ<400nm), which provides sufficient energy for the electron excitation across its band gap (i.e.,3.2eV for anatase TiO2). Only about4%of the solar spectrum can be utilized by pureTiO2. Thus, it is highly desirable to develop photocatalysts that can yield high reactivity under visible light. The visible light photocatalyst has become the research hot spot.Ag-AgX is a novel kind of plasmonic photocatalyst, which combines the property of noble metal nanoparticles surface plasmon resonanc (SPR), metal-semiconductor contact and semiconductor photocatalyst. The SPR can be modulated by tuning the size, shape and support of the noble metal nanoparticles. The SPR can enhance photocatalyst’s visible light absorption, leading to high photocatalytic efficiency.In the present work, we try to improve the fabrication methods and conditions so as to get series of visible-light-driven photocatalysts with various structures and morphology. The morphology and microstructure characteristics of as-prepared photocatalyst were characterized by means of the thermal gravimetric and transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflectance spectra (DRS) and X-ray powder diffraction (XRD).The main results of the present work were summarized as follows:1. A simple method for preparing Ag/AgCl supported on cotton fabric photocatalysts is described for the first time. AgCl particles were firstly deposited on the surface of the cotton fabric. Then the Ag+ions were reduced to Ag0species under UV light irradiation. The sample exhibits high photocatalytic activity and stability for the photodegradation of aqueous RhB and2-chlorophenol in the whole visible light region. Additionally, it is much convenient in the separation and recovery of the catalyst from the aqueous solution. As a kind of promising candidate for easy-to-recover photocatalyst, it is worth of industrial application research.2. The plasmonic photocatalyst Ag/AgCl core-shell sphere was successfully synthesized by a facile and effective method via an oxidation reaction between Ag sphere and FeCl3solution. Addition of citric acid leads to the formation of perfect microspheres (1μm in diameter) that are assembled by numerous closely packed Ag nanowires. The ratio of Fe:Ag was found to influence the morphology and the photocatalytic activity of as-obtained product, and an optimal value was determined. When the molar of Fe:Ag was1:1, the as-prepared photocatalyst showed the most pronounced photocatalytic activity and stability. The Ag/AgX (X=Br, I) core-shell spheres were prepared by a similar method.3. The plasmonic Ag-AgCl/ZnO hollow sphere, prepared by the deposition-precipitation-photoreduction method, exhibited a high photocatalytic activity for the degradation of RhB under visible light irradiation. Different morphology supports affect the as-prepared composites. The AgCl/ZnO-R shows the most pronounced photocatalytic activity. Among the Ag-AgCl/ZnO with different photoreduction duration,10-Ag-AgCl/ZnO shows the highest photocatalytic activity. We believe that the radio of Ag and AgCl was a significant factor influencing the photodegradation rate.