Ag-AgBr/SiO_2优化制备及其光催化活性研究

Optimizing Preparation of Ag-AgBr/SiO_2 and Study on Photocatalytic Activity

以SiO_2为载体,采用沉积沉淀法制备了Ag-AgBr/SiO_2光催化剂,通过优化煅烧温度和煅烧时间得到光催化活性最佳的Ag-AgBr/SiO_2的制备条件:以光催化降解罗丹明B为探针反应,当煅烧温度为773K、煅烧时间为3h时所得Ag-AgBr/SiO_2光催化活性最佳。通过X射线光电子能谱验证了Ag-AgBr/SiO_2表面的Ag物种以0价和+1价存在,并比较了Ag-AgBr、Ag/SiO_2和Ag-AgBr/SiO_2等催化剂的光催化活性,研究发现Ag-AgBr和SiO_2的协同作用能促进催化剂活性的提高和稳定性的增加。为更好地提高光催化活性,还研究了不同截体以及相同载体不同比表面积对光催化活性的影响,表面积更大的SiO_2能显著提高光催化活性。

With SiO_2 as a carrier,the Ag-AgBr/SiO_2 photocatalyst is prepared by deposition-precipitation method.In order to obtain the optimum conditions for the photocatalytic activity of Ag-AgBr/SiO_2,the calcination temperature and time are optimized.The photocatalytic degradation of Rhodamine B(RhB)is selected as model reaction,it is demonstrated that the photocatalytic performance of Ag-AgBr/SiO_2 is the best at the calcination temperature of 773 Kand the calcination time of 3 hours.In addition,the surface Ag species existed as Ag(0)and Ag(I)in Ag-AgBr/SiO_2 is confirmed by the analysis of X-ray photoelectron spectroscopy(XPS).The photocatalytic activity of Ag-AgBr,Ag/SiO_2 and Ag-AgBr/SiO_2 are compared,synergetic effects between Ag-AgBr and SiO_2 possessing the ability promote the enhancement of catalyst activity and the extension of stability is observed.The effects of different supports on photocatalytic performance are investigated to significantly improve photocatalytic activity.Besides,the effects of different specific surface area of the same carrier on the photocatalytic activity are also studied,the results show that larger surface areas of SiO_2 can obviously improve the photocatalytic activity.