Study On Preparation And Visible-light Photocatalytic Performances Of Cyclized Polyacrylonitrile/TiO₂ Nanocomposites

TiO₂ nanomaterials were prepared by a conventional sol-gel method with tetrabutyl titanate as Ti source.The polyacrylonitrile solution with dimethyl sulfoxide as solvent was added into TiO2 sols to form polyacrylonitrile/TiO2 gels,then the prepared polyacrylonitrile/TiO₂?PAN/TiO₂?gels were heat-treated to prepare cyclized polyacrylonitrile/TiO₂?CPAN/TiO₂?nanocomposites.The CPAN/TiO₂ nanocomposites were characterized by X-ray diffraction?XRD?,transmission electron microscopy?TEM?,UV-vis diffuse reflection spectroscopy?UV–Vis DRS?,photoluminescence spectroscopy?PL?,X–ray photoelectron spectroscopy?XPS?and Raman spectroscopy?Raman?.The results show that the crystal structure of TiO₂ nanoparticles modified by CPAN donot change,it's still the type of anatase.The particle size smaller while the specific surface area significantly increased.The absorbance of CPAN/TiO₂ nanocomposites is much higher than that of TiO₂ in visible light region.And the absorbance gradually enhanced with the composite proportion of CPAN/TiO2.In addition,the absorbance of CPAN/TiO2nanocomposites in visible light region increases at first and then decreases with the increasement of calcination temperature and reaction time.CPAN/TiO₂ nanocomposites display the highest absorbance when the calcination temperature is 270?and the time of calcination is 1.0 h.The upstanding electron transport properties of the conjugate structures of CPAN is favorable to the increment in the concentration of the photogenerated carriers and free radical produced by the CPAN/TiO₂ nanocomposites in the photocatalytic system,and to the decrement of the recombination probability between the photogenerated electrons and holes.The photocatalytic activities of CPAN/TiO₂ nanocomposites were evaluated by degradation of methyl orange aqueous solution.The effects of the preparation conditions such as mass ratio of PAN and TiO₂,the calcination temperature and the reaction time on the photocatalytic ablility of CPAN/TiO₂ nanocomposites under visible light were discussed.The results show that the apparent rate constant of photodegradation recation catalyzed by CPAN/TiO2 nanocomposites is 33 times of neat TiO2 nanoparticles under visible light irradiation,and the optimum preparation condition is found that the mass ratio of PAN and TiO₂ is 1:300,the calcination temperature is 270?,and the calcination time is1.0 h,Studied CPAN/TiO₂ nanoparticles in the cycle of degradation of methyl orange experiments,results show that,with the increasement of time of cyclic degradation,CPAN/TiO₂ nanocomposite particles of light catalytic activity is not much change,it showed good stability and has very good application value in the future.Also discussed the mechanism of CPAN/TiO₂ nanocomposite particles visible light catalytic.