Preparation And Characterization Of Silver Based Photocatalytic Materials

Photocatalysis as a“green”technique has attracted more attention and become one of the most important techniques of environmental remediation due to its potential application in decomposition of organic pollutants.Among various semiconductor materials,TiO₂ has been regarded as an efficient photocatalyst for its high activity,great stability,nontoxicity and low cost.However,the practical application of TiO₂ is seriously limited by its wide band gap of 3.2 eV,which can only absorb mainly ultraviolet（UV）light（4%of solar energy）.Therefore,many efforts have been dedicated to preparing more visible light driven（VLD）photocatalysts for efficient use of solar energy.To further improve the photocatalytic efficiency of silver-based photocatalytic materials,the present investigations are focusedonsynthesizingtheAg/Ag₃PO₄/g-C₃N₄,Ag/AgCl/TiO₂and macro/mesoporous TiO₂/Ag₃PO₄ composites via different methods,such as calcination,hydrothermal treatment,coprecipitation and photo-reduction method,et al.The main results can be summarized as follows:1.The Ag/Ag₃PO₄/g-C₃N₄ sheet-like nanocomposites has been synthesized via an in-situ deposition method and show highly photocatalytic performance for degradation of Rhodamine B aqueous solutiom.It is found that Ag/Ag₃PO₄ was deposited on the surface of g-C₃N₄ nanosheets,and the visible light absorption of Ag/Ag₃PO₄/g-C₃N₄ nanocomposites has been significantly enhanced in comparation with Ag/Ag₃PO₄ and g-C₃N₄.The as-prepared Ag/Ag₃PO₄/g-C₃N₄ photocatalyst exhibits an obviously higher photocatalytic activity for degradation of Rhodamine B than Ag/Ag₃PO₄ and g-C₃N₄ samples.2.The Ag/AgCl/TiO₂ photocatalysts have been synthesized via precipitation and photoreduction methods.The photocatalytic performance of Ag/AgCl/TiO₂nanocomposites has been improved significantly,which is higher than that of the TiO₂ and AgCl/TiO₂ by a factor of 5.1 and 3.1 times,respectively.In addition,the trapping experiments indicate that the superoxide and hole are the major active radicals in the process of photocatalytic degradation of Rhodamine B.3.The TiO₂/Ag₃PO₄ photocatalysts have been prepared by a facile hydrothermal method by using macroporous/mesoporous titanium dioxide,silver nitrate and disodium hydrogen phosphate as precursors.The samples are analyzed by field emission scanning electronic microscopy,UV–vis spectrophotometer and nitrogen adsorption apparatus.The photocatalytic activity is evaluated by degrading Rhodamine B（1.0×10^-55 mol/L）aqueous solutin.It is found that TiO₂/Ag₃PO₄photocatalyst shows higher photocatalytic activity than pure TiO₂ and Ag₃PO₄.And the photocatalytic mechanisms are further discussed.