| In recent years, photocatalytic technique which use the sunlight as an energy source is harmless to the environment and has achieved great advancement. The traditional photocatalysts have a large band gap and can not utilize solar energy. So the exploration of the catalysts with visible light response is very necessary. And g-C3N4 itself has response to the visible light, thus it has been widely used in many aspects. By changing the electron-deficient of Polyimide(PI) and then gives a strong photooxidation. g-C3N4(s)/PI composites can not only enhance the absorption of light, but also improve the removal rate. The following two aspects were studied in this paper:(1) PI photocatalysts were synthesized through a conventional calcuation method which used melamine and pyromellitic dianhydride(PMDA) as materials. By incorporating PMDA monomer into netwok of g-C3N4,the electronic structure of PI has been changed, the VB position can be largely decrease and thus, gives a strong photooxidation capability. In comparison with g-C3N4, PI shows the better absorption in visible region and better photocatalysis activity. The results of RhB degradation under visible light showes PI(1:1) is the best and the removal rate is 1.9 times compared with that of the g-C3N4 and the stability is very good.(2) The g-C3N4(s)/PI composites were prepared by g-C3N4(s) and PI, XRD and DRS has resulted that g-C3N4(s)/PI has been successfully fabricated. TEM shows it is layered, and the diameter is less than 100 nm. PL shows that the rate of separation efficiency of electronicholes is very high. DRS shows it has good absorption in visible light. The specific surface is 13.8 m2/g. The result of RhB degradation under visible light showes that the removal rate of g-C3N4(s)/PI is 3.15 times compares with that of the PI. Furthermore, the g-C3N4(s)/PI composites shows good stability in photocatalytic process. |
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