Preparation Of Ag₂SO₃/AgBr Based Composites As Visible Light Photocatalysts And Their Application In Degradation Of Organic Dyes

The degradation of organic dye pollution in water is of importance in human health. Photocatalytic degradation of organic pollutant is an efficient and environmentally friendly method. Silver salts based visible light active photcatalysts have been extensively studied and applied in photodegradation of organic dyes waste.In the present work, based on our previous Ag₂SO₃/AgBr composite,two novel visible light photocatalysts, CuO/Ag₂SO₃/AgBr and GO/Ag₂SO₃/AgBr, have been prepared. Both of the composited materials showed enhanced photocatalytic activity and stability in comparison with Ag₂SO₃/AgBr composite. A variety of characterization methods were employed to investigate the structure, morphology, optical absorption properties and photocatalytic performance of these composited materials.The relationship between the microstructure and the light catalytic properties of these materials has been revealed. The main content of this paper is summarized as follows:First, CuO nanosheets were prepared by hydrothermal method. Then,Na2SO3 solution was gradually dropped into a CuO and AgNO3 mixed solution, forming CuO/Ag₂SO₃ composite precipitation. Finally, KBr solution was added into the mixed solution drop by drop and theCuO/Ag₂SO₃/AgBr composite was obtained by ion exchange reaction.The prepared CuO/Ag₂SO₃/AgBr composite exhibits high-efficiency ability to photodegradate three typical organic dyes（methyl orange,methylene blue and rhodamine B）. Here CuO may act as a cocatalyst to inhibit the recombination of electron–hole pairs of composite.Besides, CuO/Ag₂SO₃/AgBr composite can degrade three typical organic dyes through catalytic wet air oxidation（CWAO） under dark,even for methyl orange（MO） with high initial concentration. Here O2 plays an important role in oxidation and formation of super oxygen free radical during the reaction process. A possible reason may be the formation of H2O2 in the presence of CuO and oxygen effectively degradate organic dyes under dark.At last, uniform Ag₂SO₃/Ag Br nanoparticles enwrapped in high-surface-area GO sheets were prepared. Ag₂SO₃/GO was first fabricated by electrostatically-driven assembly of positively charged Ag⁺on the negatively charged GO sheets and followed by in situ deposition of Ag₂SO₃. Then GO/Ag₂SO₃/AgBr composite was formed by ion-exchange reaction. This composite showed higher efficient degradation of three typical organic dyes in water under visible light irradiation in comparison with Ag₂SO₃/AgBr. The remarkable enhanced photoactivity can be ascribed to the ability of GO to prompt charge transfer and suppress the recombination of electron-hole pairs.