Preparation And Properties Of Ag Doped SiO₂-TiO₂Aerogels Via Ambient Pressure Drying

As a kind of high efficient photocatalyst, SiO2-TiO2aerogel has a significant value in fields of environmental governance and energy production and so on because of its large specific surface area, strong nanonetwork structure, high adsorption and photocatalytic activity. However, using supercritical drying to prepare aerogel shows many shortcomings and anatase could be obtained by high temperature calcinations which would decrease the surface area of aerogel. Besides, doping Ag can improve the photocatalytic performance of aerogel. So that it is very important to use ambient pressure drying to prepare Ag doped SiO2-TiO2aerogel with high surface area and good anatase without calcinations.In the paper, Ag doped SiO2-TiO2aerogels with high surface area of484.9cm2/g and good anatase without calcinations was prepared via ambient pressure drying. For the preparation process, ionic liquid as co-solvent and silver nitrate as the doping agent and acetic acid and urea as catalyst were used. Xerogel was aged by ionic liquid aqueous solution and then ionic liquid was removed by ethanol and cyclohexane.Ionic liquid [C4mim]Br has effect on the formation of the network structure of SiO2-TiO2aerogels. A balanced amount of [C4mim]Br as co-solvent and proper concentration of [C4mim]Br aqueous solution as aging liquid are conducive to the formation of anatase microcrystalline in SiO2-TiO2aerogels. Special solubility and dispersing effect of IL to sol-gel precursors were estimated to cause the results above. In the experiment, n (IL)/n (SiO2+TiO2)=1and1mol/L aging liquid concentration are the best conditions, respectively.Doping Ag of proper amount can improve the photocatalytic performance of SiO2-TiO2aerogels to a certain extent. But the excess amount of Ag doped could decrease photocatalytic performance of SiO2-TiO2aerogel. The best amount of Ag is n(Ag)/n(SiO2+TiO2)=1%.SiO2-TiO2aerogels with high surface area and good anatase could be prepared using ionic liquid [C4mim]Br or [C12mim]Br as co-solvent via ambient pressure drying. And SiO2-TiO2aerogel using ionic liquid [C4mim]Br as co-solvent has higher surface area and better anatase microcrystalline.