The Band Gap Structure And Photocatalytic Properties Of Elements Doped Perovskites Materials

Nowadays,semiconductor photocatalytic technology is of particular interest because of photocatalytic water splitting to H₂ and photocatalytic degradation of organic pollutant.Perovskite compounds have attracted considerable attention due to its stable structure,no repollution and nontoxicity.However,most of perovskite photocatalyst can only absorb ultraviolet light,which limits its application and the use of solar energy,so broaden the region of light absorption of perovskite photocatalyst is a key problem to be solved for the photocatalytic effciency.In this thesis,the SrTiO₃ and SrZrO₃ nanoparticles were successfully synthesized by the sol-gel method.Different elements were doped into SrTiO₃and SrZrO₃,and the optical absorption of SrTiO₃ and SrZrO₃ has been broadened successfully.The main contents of this thesis are as follows:1.SrTiO₃ nanoparticles were successfully synthesized by the sol-gel method.The SrTiO₃ sample with single element doping was also synthesized with sol-gel method.The influence of different elements on the spectral absorption range and impurity level was studied.The absorption spectra of the products were investigated.We obtained the photocatalytic degradation of methylene blue?MB?for the different samples under visible light and discussed the factors that affect the photocatalytic efficiency and the internal mechanism.The band gap of ion doped SrTiO₃ is about 2.0 eV,the absorption region extend from UV to visible light and it can be used to degrade MB solution under visible light.2.The co-doped SrTiO₃ samples were synthesized.Some vacancies and defects were formed in order to keep the charge balance in the mono-doped SrTiO₃.These defects and vacancies as recombination sites can enhance the recombination of photogenerated electrons and holes,which results in decreasing the photocatalytic activities.The element codoping can keep the charge balance to reduce the vacancies and defects,which leads to the increase of the photocatalytic activities.La/Ni co-doped SrTiO₃ photocatalyst showed a higher degradation rate of MB solution.3.Transition elements doped SrZrO₃ nanoparticles were prepared and the influences of different dopants on the absorption spectra of the products were investigated.In addition,the degradation mechanism of MB solution for the photocatalyst under the irradiation of UV light and visible light was discussed.Mo or Cr doped in SrZrO₃ extended its photoresponse region and improved the degradation rate of MB solution due to the influence of impurity energy levels.4.The pseudo-first-order kinetic analysis of photocatalytic degradation for MB solution with perovskite compounds was studied.We also studied the cycle performance of the perovskite compounds.The degradation rate of the MB solution was more than 85%of the original rate after reused of the doped SrTiO3 and the doped SrZrO3 three times.This means that the doped SrTiO₃ and the doped SrZrO₃ had good reuse stability and high photocatalytic activity.