Copper-doped TiO₂/SiO₂Composite Aerogel Synthesized By Ambient Pressure And Its Photocatalytic Activity

The common method to prepare SiO2/TiO2composite aerogels is supercritical drying,with requiring further heat treatment, to obtain crystallized materials. However, supercriticaldrying is so expensive, complex to operate. At the same time, the calcination step can resultin particle agglomeration, grain growth, decrease in specific surface area and breakage of theinitial nanostructures,which will have an adverse influence on the photocatalytic activity ofthe material. Therefore, it is highly desirable to synthesize SiO2/TiO2composite aerogels withgood anatase nanocrystal at an ambient pressure without any further heat treatment.According to the literature, doped transition metal can intrduce defects into TiO2lattice,extend the light response range and promotes photocatalytic activity under visible light.Transition metals can be used to futher modify SiO2/TiO2composite aerogels with strongability to absorb visible light and enhanced photocatalytic performance under visible light.The main research content of this experiment are as follows:(1) SiO2/TiO2composite aerogels with mesoporous network structure, high surface areaand good anatase nanocrystal were prepared at low temperature by a simple sol-gel methodwith an ambient pressure drying process, using ionic liquids as a template and aging solution.The structure properties of the sample were characterized by XRD, SEM,TEM and N2adsorption–desorption. The reactive brilliant blue KN-R was chosen as the model to evaluatethe photocatalytic activity of all samples under UV light. The SiO2/TiO2composite aerogelsprepared with the molar of Si/Ti equals to0.1at60℃for5d exhibite high photocatalyticactivity with large specific surface area of330.773m2/g, an average pore diameter of7.5nmand good anatase nanocrystal after dried at60℃.(2) Copper doped SiO2/TiO2composite aerogels with high photocatalytic activity undervisible light were prepared at low temperature by a simple sol-gel method with an ambientpressure drying process, using ionic liquids as a template and aging solution withCu(NO3)2·3H2O as copper source. The structure properties of the sample were characterizedby XRD, UV-VIS, SEM, TEM, EDS and N2adsorption–desorption. The reactive brilliant blue KN-R was used to examine the photocatalytic activity of all samples under direct solarirriadation. The dopant of Cu with low content can not affect the phase composition, apparentmorphology and microstructure of SiO2/TiO2composite aerogels. With the increasing of Cucontent, the absorption intensity of the sample increased in the range of400–800nm.Experimental results of photocatalytic degradation of reactive brilliant blue KN-R underdirect solar irriadation show that proper doping content of Cu can further enhance thephotocatalytic performance of SiO2/TiO2composite aerogels under visible light. With theincreasing of Cu/Ti molar ratio, the photocatalytic activity of the sample increased andreached a maximum value when the molar ratio of Cu/Ti was0.005:1. However, the activityobviously decreases with further increasing Cu concentration.