Study On The Preparation And Photocatalytic Performance Of Silver Sulfide Composite Photocatalyst

The rapid development of the world economy and technology has inevitably caused serious environmental pollution problems and energy shortages.Among them,the widespread use of antibiotics and the indiscriminate discharge of dye wastewater from the textile industry,combined with its poor biodegradability and high toxicity to aquatic organisms and humans,have posed a serious threat to human society and the natural environment.Solar-powered photocatalytic oxidation-based technology is considered to be the most promising method for efficient wastewater treatment because it is clean,non-toxic,energy-efficient,and highly effective,thus allowing efficient catalytic degradation of difficult-to-decompose organic pollutants in the aqueous environment.In this paper,Ag2S is used to improve the photocatalytic performance of the composite system by having a high absorption coefficient and a wide range of light absorption,and the relevant studies are as follows.(1)Ag2S/Ag2CO3 heterojunctions were designed to improve the problems such as fast rate and poor stability of Ag2CO3 semiconductor carrier complexation.characterization results such as XRD,XPS,SEM and TEM showed that Ag2S nanoparticles were successfully formed on the surface of Ag2CO3 material and Ag2S/Ag2CO3 heterojunctions with core-shell structure were successfully prepared.The photocatalytic experiments confirmed that the Ag2S/Ag2CO3 composites have more excellent photocatalytic activity than the pure phase materials and can degrade 97%of RhB within 25 min,while the pure phase materials are less than 10%.The results of the catalytic mechanism study showed that the main catalytically active species of the Ag2S/Ag2CO3 heterojunction were ·O2-and h+.The improved performance of the composite photocatalyst is attributed to the construction of the heterojunction which accelerates the migration of photogenerated carriers and avoids the compounding of electron-hole pairs.(2)Ag2S/Ag2CrO4 heterojunctions were successfully constructed by anionexchange preparation technique by choosing Ag2CrO4 as the precursor.It was found that the ordered arrangement of Ag2S nanoparticles on the surface of Ag2CrO4 could broaden the light absorption range of the composite photocatalyst.The degradation experiments on RhB showed that the degradation rates of the best ratio composites were 2.3 and 48 times higher than those of Ag2CrO4 and Ag2S,respectively.In addition,the cycling efficiency and pre-and post-cycle XRD patterns confirmed the high catalytic stability of the composite photocatalysts.(3)In order to further prepare the composites with better performance,Ag2S/Ag3VO4 heterojunction composite photocatalysts were successfully prepared by combining in situ ion exchange and hydrothermal methods and by regulating the synthesis process conditions.The results of photocatalytic experiments show that the 40%-Ag2S/Ag3VO4 composite photocatalyst has enhanced photocatalytic activity and the catalytic rate is 4.5 times higher than that of the pure phase Ag3VO4.The greatly improved performance of Ag2S/Ag3VO4 composite photocatalyst is mainly attributed to the following two aspects:on the one hand,Ag2S provides strong light absorption for the composite system with its wide light absorption range,and on the other hand,the heterojunction of Ag2S/Ag3VO4 heterojunction provides strong light absorption for the composite system.On the other hand,the formation of heterojunction largely promotes the transfer of internal photogenerated electrons,which enables the efficient degradation of organic pollutants by photogenerated holes.Therefore,the Ag2S/Ag3VO4 composite system is a promising catalytic material.Figure[30]table[6]references[108]...