| Water pollution problems are more and more prominent, which have threated greatly people’s health. In order to seek a more efficient, green and low energy consumption of environmental pollution treatment technology, photocatalysis oxidation technology has been more and more aroused people’s attention. Recently, people have begun to pay close attention to new-typed visble light semiconductor photocatalyst, which has higher photocatalytic performance than traditional photocatalyst.This paper mainly studied the structure, photocatalytic performance and catalytic degradation mechanism of new-typed visble light semiconductor photocatalyst of Ag@AgCl/Bi2WO6. The crystal structure, morphology, chemical composition, optical absorption properties, surface adsorption and combined price state structure of composite catalysts were analyzed carefully by different characterization methods. The optimum reaction conditions in the process of photocatalytic reaction were determined through the photocatalytic experiments. In addition, the Ag@AgCl/Bi2WO6 photocatalytic reaction mechanism was put forward according to the valence band structure of Ag@AgCl/Bi2WO6 and results of free radicals trapping experiment. The main contents and conclusions were listed as follows:1. Ag@AgCl/Bi2WO6 catalysts were successfully prepared by the hydrothermal method and the two-step synthetic method. The physical and chemical properties of catalysts were determined by different characterization methods, the results showed that Ag@AgCl/Bi2WO6 have high purity and crystallinity, better crystal shape; from SEM figures, it is clearly seen that cube-like Ag@AgCl deposited on the surface of the flower-like Bi2WO6; the composited Ag@AgCl and Bi2WO6 broadened visible light response range of Bi2WO6, the composite catalysts have obvious red shift compared with the pure Bi2WO6; it is found that the N2 adsorption-desorption isothermal conforms to Ⅳ-type isotherm through the determination of the adsorption characteristics of Ag@AgCl/Bi2WO6 by BET method, and specific surface area of the composites turned smaller after composited, this is mainly due to the Ag@AgCl is deposited on the surface of Bi2WO6. As shown in the XPS spectra of Ag@AgCl/Bi2WO6 catalysts, which composed of Bi, W, O, Cl, Ag elements, among them, the chemical valence of Bi elements in Ag@AgCl/Bi2WO6 is +3 valence, and main chemical valence of W elements is +6 valence, which is corresponding W6+ oxidation state. O elements exist two forms of lattice oxyen ions and the surface hydroxyl oxyen, and Ag elements exist elemental metal Ag and Ag+ two chemical valence state forms.2. Environmental estrogen bisphenol A served as target contaminant, and photocatalytic degradation experiment was operated under the simulated sunlight. Results showed that Ag@AgCl/Bi2WO6 photocatalytic performance is generally better than pure Bi2WO6 photocatalytic performance. Among them, the AB-0.2 photocatalytic effect was best; the photocatalytic optimal reaction condition was that the initial concentration of bisphenol A was 3 mg/L, catalyst dosing quantity was 0.03 g, pH=11, after irradiation for 1 h under visible light, the degradation ratio of bisphenol A with Ag@AgCl/Bi2WO6 composites was 92.53%; the photocatalytic degradation process for bisphenol A with different catalysts conformed to the first order reaction kinetics model through the comparative analysis.3. The degradation mechanism of Ag@AgCl/Bi2WO6 was investigated through free radicals trapping experiment. It is found that -O2- free radicals and hole was the main active substances, which played a leading role in the process of photocatalytic reaction; according to the valence band structure of the Ag@AgCl/Bi2WO6 and free radicals trapping experiment, the Z photocatalytic reaction mechanism of Ag@AgCl/Bi2WO6 was proposed. Ag@AgCl/Bi2WO6 had the better photocatalytic performance under visible light, which mainly attributed to its appropriate valence band structure and the influence of the deposition of Ag nanoparticles on the surface of catalysts. |
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