RESUMO
In the present paper, ordered mesoporous silica (KIT-6) as support, nanosized TiO2 into KIT-6 was synthesized by titanium tetraisopropoxide hydrolysis. Then silver was loaded by deposition-precipitation method. Ag-TiO2/KIT-6 composite nanosized photocatalyst was firstly synthesized and a series of correlated catalysts were synthesized by the same preparation method. Methyl orange is presently adopted as a representative organic pollutant to evaluate the photocatalytic performance of the as-synthesized catalysts. The order of photocatalytic activity of the as-synthesized samples was found as Ag-TiO2/KIT-6 > Ag/TiO2 > TiO2/KIT-6 > TiO2 > Ag/KIT-6. Detailed characterizations were conducted by techniques including XRD, N2 physical adsorption, XPS, UV-Vis DRS and TEM. It was found that the Ag-TiO2 /KIT-6 sample shows the highest photocatalytic activity, which should be attributed to the Ag-TiO2 heterojunction structure and higher BET surface area of the Ag-TiO2/KIT-6 sample. Ag-TiO2 heterojunction improves the separation of photogenerated electron-hole pairs, thus enhancing the photocatalytic activity; Ag-TiO2/KIT-6 sample possesses high BET surface area, which facilitates adsorption and transportation of dye molecules, also leading to higher photocatalytic activity.