Preparation Of PAN/Ag/ZnO Microporous Membrane And Study On Visible Light Photocatalytic Performance

In this paper,polyacrylonitrile(PAN)was used as a raw material to prepare polyacrylonitrile/silver/zinc oxide(PAN/Ag/ZnO)microporous membrane with photocatalytic properties by electrospinning,electroless silver plating and hydrothermal reaction.The photocatalytic performance of PAN/Ag/ZnO microporous films on rhodamine B(RhB)solution under visible light was systematically studied.Through the use of different analysis and testing methods,the ZnO with different morphologies was analyzed in detail,and the effect of ZnO with different morphologies on the photocatalytic performance of microporous membranes were was investigated.In addition,samples without electroless silver plating were also prepared.Then samples with and without silver layer were compared from the aspects of morphology and photocatalytic performance.Firstly,PAN nanofiber microporous membrane was prepared by home-made electrospinning setup.According to our previous researches,for electrospinning PAN/DMF solution,when the spinning solution concentration was 10wt%,the holding voltage at both ends was 12kV,the distance between the spinneret and the receiving roller is 13cm,and the spinning velocity was 0.6ml/h,PAN fibers deposited on the collector randomly and presented desirable morphology without beads in the membrane.The PAN nanofiber membrane was sensitized and activated,and then the nanofiber was electrolessly plated with a silver ammonia solution to prepare PAN/Ag nanofiber microporous membrane.Scanning electron microscopy images showed that silver adhered closely to the fibers in a granular and massive form and covered nanofibers.X-ray energy spectroscopy(EDS)confirmed that silver exists as a simple substance.The PAN/Ag microporous membrane was repeatedly placed in a zinc acetate/anhydrous ethanol mixed solution and dried.X-ray energy spectroscopy(EDS)and surface sweeping element mapping(Mapping)showed that a large number of ZnO growth points were uniformly implanted on the surface of silver-plated nanofibers.The PAN/Ag microporous membrane with ZnO growth point was placed in a zinc nitrate/urotropine/aqueous ammonia solution,and various morphological nano-zinc oxides were grown at the growth point by adjusting the concentration of the solution.Scanning electron microscopy(SEM)and transmission electron microscopy(TEM)analysis showed that the grown nano-zinc oxides were rod-shaped,flower-like,flaky and honeycomb-like,all corresponding to the zinc oxide(100)surface.X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS)further confirmed the presence of zinc oxide of hexagonal wurtzite.The photocatalytic performance of microporous membranes grown with nano-sized zinc oxide with different morphology was tested under visible light.It was found that the microporous membranes grown with rod-shaped zinc oxide had the best performance under visible light.After 6 hours of visible light irradiation,only The degradation efficiency of the PAN/Ag/ZnO film containing only 2mg ZnO nanorods to RhB solution reached 98%,and the performance of the samples did not significantly decrease after 5 repeated experiments.Compared with the non-silvered samples,the photocatalytic efficiency of the silver-plated samples was greatly improved.