Research On Photoelectric And Photocatalytic Performances Of Mesoporous TiO₂

As a renewable energy source,solar energy has the advantages of pollution-free and huge reserves,making it most likely to become a substitute for fossil energy,and will account for a larger proportion in the energy structure.Research on solar energy utilization technology can be br oadly classified into three categories: the first is solar thermal energy utilization technology;the second is solar photovoltaic power generation that converts light energy into electricity utilizing the photovoltaic effect of semiconductors and other ma terials;the third is based on the photochemical principles to treat semiconductor as catalyst for photocatalysis.As a semiconductor material with good stability and high chemical activity,TiO₂ is widely used in the fields of photoelectric conversion an d photocatalytic degradation.Dye Sensitized Solar Cell?DSSC?has attracted wide attention due to its advantages of low cost and high conversion efficiency.As the DSSC photoanode material,TiO₂ affects the dye adsorption,light absorption and electron transport directly,and thus affects the photoelectric efficiency.In the process of photodegration of organics,TiO₂ influences the amount of organic adsorption and adsorption rate,and then affects the degration rate of organics.In this work we first prepared DSSC photoanode materials with different structures,which are mesoporus TiO₂ with a porous structure,yolk-shell TiO₂ with a hollow structure and spindle TiO₂ with a large aspect ratio.Then we used the particles above to manufacture the photoanode b y method of doctor blade printing and further finished the fabrication of DSSC.First we verified the special properties of TiO₂ with different structures indirectly by testing the basic performances of the DSSCs.Then we tested the I-V characteristic of DSSCs and the results showed that the DSSC with mesoporous TiO₂ had the highest photoelectric conversion efficiency.And then we used DSSC assembled with mesoporous TiO₂ to further explore the effects of different factors on DSSC photoelectric conversion efficiency,it is found that the efficiency went up with the increase of the thickness of the photoanode film;the increase in the specific surface area led to an increase in the amount of dye adsorption and thus to an increase in efficiency;before reaching a specific temperature the efficiency increased as the temperature rose up,and after that it began to fall.Then,mesoporous TiO₂ was used for the research on photodegration peformances.First,the performances of mesoporous TiO₂ and commercial P25 particles in degrading Methyl Orange,Methylene Blue and Rhodamine B were compared and it was found that mesoporous TiO₂ showed great advantages in the photodegration of Rhodamine B.Then the effects of reaction temperature,concentration of catalyst and calcination temperature of TiO₂ on the degradation rate were investigated,and it was found that the increase of temperature promoted the reaction on the one hand,but at the same time it reduce d the adsorption rate,thus the degradation rate show ed a tendency of falling first and then rising.As the concentration of catalyst increases,the amount of dye adsorption first rised up and then reached the saturation value,which conduce that the degration efficiency stay stablised after rising up.The calcination of the catalyst made the the grain size grow larger,and the p H value of the solution dispersed with calcinated TiO₂ particles increases.Both of the aspects were not conducive to the dye adsorption and degradation reaction,resulting in a decrease in the degradation rate as the calcinatng temperature increases.