The Research Of Modification And Loading Of Nanometer Titanium Dioxide Photocatalyst

The aim of the research is to solve the arising problems of nanometer titanium dioxide photocatalyst in its practical application. The work has emphasized upon the modification and loading of the photocatalyst. Photocatalyst has been modified by a process to form composite semiconductors and to dope with metal ion. It has been loaded via sol-gel process and dip-coating method.In the research, a uniform and transparent nanometer thin film photocatalyst of titanium dioxide and modified titanium dioxide has been prepared via sol-gel process and loaded firmly on the surface of glass.The various measures have been adopted and the effecting factors have been systematically observed and the mechanism of action has been fully analysed. The results are showed as follows:Under the excitation of UV lamp radiation, SiO2-TiO2 composite thin film has shown photocatalytic activity improvement in comparison with the titanium dioxide one. However, under florescence high-pressure mercury lamp the photocatalytic activity of SiO2-TiO2 composite thin film is lower than that of titanium dioxide one. In consequent, owing to the decrease of anatase crystal grains, which has caused the increase of quantization effect and the ability of reactant adsorption, it has induced a blue shift in the absorption spectra.Under both aforesaid radiations, the photocatalytic activity of SnO2-TiO2 composite thin film was obviously higher than that of titanium dioxide one. By visible light in particular, the photodegradation rate of SnO2-TiO2 composite thin film was 34% higher than that of titanium dioxide one. The mechanism of favourable action of stannic oxide was due to anatase and rutile model, (Sn,Ti)O2, solid solution has caused a heterogeneity structure of composite semiconductors, which has given rise to the effective separation of photoproduced carriers and improved their life time. The intermediate energy level which has been generated by structure defect has decreased the electron transition energy and caused the red shift of the absorption spectra and therefore would extend the absorption range and enhance the absorption intensity of visible light.Fe3+ ion-doped SiO2-TiO2 and SnO2-TiO2 composite thin films improved the photocatalytic activity as it would capture photoproduced carriers in a simple energy level and prolong the lifetime of the carriers. Especially, the effect of Fe3+ ion-doped SnO2-TiO2 composite thin film was remarkable.The research has combinatively used various modification methods and has successfully prepared Fe3+-SnO2-TiO2 composite thin films photocatalyst. By which, under the condition of visible light, the photodegradation rate of methyl orange could reach 89.65%, which is 45% higher than that of titanium dioxide one.Researches about Fe3+-SnO2-TiO2 composite thin films has not been found reported so far. The research could be a new way in promoting the practical application of photocatalyst based on titanium dioxide.