Study On Visible-light Photocatalytic Activities Of Composite Materials Of Conjugated Polyene Derivatived From PVC And Ag₃PO₄

Ag₃PO₄ particles were synthesized with silver nitrate and sodium hydrogen phosphate as the main raw material by different methods,such as single injection of silver complexation ion,double injection of silver nitrate solution and disodium hydrogen phosphate solution,single injection of silver nitrate solution,and single injection of disodium hydrogen phosphate solution.The results of scanning electron microscopy?SEM?analysis show that Ag₃PO₄ particles prepared by single injection of silver nitrate solution possess spherical morphology with an average diameter of about 300 nm.X-ray diffraction?XRD?patterns give further support to cubic structure of the as-synthesized samples.The photocatalytic performances of the Ag₃PO₄ were investigated by decomposing methyl orange?MO?.Results show that photocatalytic activity of Ag₃PO₄ prepared by single injection of silver nitrate solution is significantly better than any other preparation method above mentioned.Ag/Ag₃PO₄ composite particles-were synthesized by photoreduction method,vanillin reduction method,and sodium citrate reduction method.The composite particles were characterized by transmission electron microscopy?TEM?,UV-vis diffusion reflectance spectroscopy?DRS?,and photoluminescence?PL?.Results show that the average diameter of Ag/Ag₃PO₄ composite particles approximately 300 nm,of silver particles deposited on the surface about 10 nm.The high absorbance of Ag/Ag₃PO₄ in the region of 400-500 nm is attributed to the plasmon resonance of silver nanoparticles deposited on the Ag₃PO₄ particles.Photocatalytic degradation of methyl orange results show that Ag/Ag₃PO₄ prepared by sodium citrate reduction possesses the highest photocatalytic activity.The visible light photocatalytic activity initially increases,and then decreases with the increment in the molar ratio of Ag and Ag₃PO₄,and the optimum molar ratio is 1:5.The effects of EDTA?photogenerated holes scavenger?and DMSO?photogenerated electrons scavenger?on the photodegradation rate of MO under visible light irradiation reveal that the photogenerated holes is the active species for the degradation of MO.The composite materials of conjugated polyene derivatived from PVC/Ag₃PO₄?CP-PVC/Ag₃PO₄?were prepared by Ag₃PO₄ dipped in THF solution of PVC and heat treatment.It can be seen from SEM picture that the average diameter of composite materials is about 300 nm,and CP-PVC moleculars are distributed on the surface of Ag₃PO₄.The XRD patterns give support to cubic structure of composite materials.The modification of CP-PVC does not alter the crystalline structure of Ag₃PO₄.The UV-vis diiffusion reflectance spectra of CP-PVC/Ag₃PO₄ composite materials exhibit distinct stronger absorbance in the visible light range of 400-800 nm compared with pure Ag₃PO₄.The visible-light absorbance of composite materials increases correspondingly with the increase of content of CP-PVC,the increase of heat treatment temperature,and the decrease of heat treatment time.The PL emission intensities of composite materials are weakened than that of pure Ag₃PO₄,indicating that the compound of CP-PVC can inhibit the recombination of charge carriers and thus result in PL quenching.The PL emission intensity of composite materials decreases correspondingly with the increase of content of CP-PVC.The results of photocatalytic degradation of methyl orange indicate that the photocatalytic efficiency initially increase and then decrease with the increase of the content of CP-PVC,the increase of heat treatment temperature,and the prolonging of heat treatment time.It can be found that the optimum prepared conditions are as follow:the mass ratio of CP-PVC and Ag₃PO₄ is 1:3000,heat treatment time is 2h,and heat treatment temperature is 130?.The apparent rate constant for degradation of methyl orange catalyzed by CP-PVC/Ag₃PO₄ is 4.2 times of pure Ag₃PO₄.