Preparation And Photocatalytic Performance Of Ag₂S/WO₃ Composite Materials

In recent years,photocatalytic technology using semiconductor oxides has developed rapidly and attracted much attention of researchers.Semiconductor photocatalytic degradation of organic pollutants has the advantages of clean,non-toxic,high energy efficiency,no secondary pollution and simple process.So far,the photocatalyst with broad band gap semiconductor as the main research object has limited light response range,and can absorb only about 5%of solar energy.The light response range is relatively narrow,and most of the sunlight can not be utilized.Narrow bandgap semiconductors,such as W03,have attracted much attention and have been widely developed and studied.As an indirect bandgap semiconductor(Eg?2.5-2.8 eV),WO3 can absorb 12%of the sunlight and respond to nearly 500 nm of visible light The wide band gap and narrow band gap of WO3 make it have good photoelectric response under visible light conditions.However,the absorption range of sunlight is still limited,and 50%of the infrared light can not be used.In addition,the research on the full-spectrum photocatalyst supported on WO3 is very few.In this paper,the full-spectrum Z-band photocatalyst was fabricated using WO3 as the load.The specific work is as follows:Firstly,WO3 and Ag2S were successfully prepared,and the degradation of methylene blue(MB)by WO3 and Ag2S was studied.Secondly,Ag2S/WO3 composites were successfully prepared by two-step method.The degradation of MB by Ag2S/WO3 composite was studied and compared with that by WO3 composite.The results showed that the degradation rate of MB by Ag2S/WO3 composite was higher than that of WO3 under the same photocatalytic degradation conditions.The photocatalytic mechanism of the two catalysts was analyzed from the point of view of energy band structure.The results showed that the high photocatalytic efficiency of Ag2S/WO3 composite was attributed to the formation of Z-band heterojunctions and the photocatalytic activity using full spectrum.Lastly,Ag2S/Ag/WO3 composites were further prepared by two-step method.The degradation of MB by Ag2S/Ag/WO3 composites was also studied.The degradation of MB was compared with that of WO3 and Ag2S/WO3 composites.The results showed that under the same conditions,the degradation rate of MB by Ag2S/Ag/WO3 composite was the highest.The photocatalytic mechanism of different catalysts was analyzed from the point of view of band structure.The results showed that the high photocatalytic efficiency of Ag2S/Ag/WO3 composites was attributed to the formation of Z-band heterojunctions with conductive media and the photocatalytic activity using full spectrum.