Preparation And Photocatalytic Properties Of Zno Nanofibers And Its Composite Nanofibers

In this paper, PVP/Zn(CH₃COO)₂, PVP/Zn(CH₃COO)₂/Fe(NO₃)₃ and PVP/Zn(CH₃COO)₂/ Cu(NO₃)₂ composite nanofibers were prepared by electrospinning using polyvinglpyrrolidone (PVP), zinc acetate dehydrate(Zn(CH₃COO)₂·₂H₂O), Iron(â…¢) nitrate nonahydrate(Fe(NO₃)₃·9H₂ -O) and Copper(â…¡) nitrate trihydrate(Cu(NO₃)₂·₃H₂O) as starting materials. ZnO, ZnO/Fe₃O₄ and ZnO/CuO nanofibers were obtained by high temperature sintering of above composite nanofibers. And preliminary study was carried out on their photocatalytic properties.(1) PVP/Zn(CH₃COO)₂ composite nanofibers had been prepared by electrospinning, and electrospinning parameter was investigated. It was found that the average diameter of fibers incr -eased with increasing the content of PVP and Zn(CH₃COO)₂. Voltage, flow rate and solidifying distance had a certain effect on fiber membrane morphology. And only when in a certain range, good spinning effect and uniform fibers can be obtained. ZnO nanofibers were obtained by high temperature sintering of above composite nanofibers. Field-emission scanning electron microsco -pe(FE-SEM), thermal gravimetric analysis(TG), energy dispersive spectroscopy(EDS),fourier transform infrared spectroscopy(FTIR) and X-ray diffraction(XRD) were used to characterize fibers before and after sintering. The results showed that the morphology and the crystallinity of the fibers were largely influenced by the sintering temperature. When compared to PVP/Zn(CH₃ -COO)₂ composite nanofibers, ZnO nanofibers became markedly fine and the surface of fibers became coarse with the sintering temperature increasing. However, the nanofibers occured breakage when the sintering temperature was too high. X-ray diffraction patterns showed us the crystallinity became better with the increasing of the sintering temperature. Taking methylene blue and methyl orange for dye pollutant model, photocatalytic properties of ZnO nanofibers had been studied. The results showed when the sintering temperature is at 700°C, ZnO nanofibers for two dye pollutant all had a good photocatalytic properties and a good reuse performance.(2) PVP/Zn(CH₃COO)₂/Fe(NO₃)₃ composite nanofibers were prepared by electrospinning, and magnetic ZnO/Fe₃O₄ composite nanofibers were obtained by high temperature sintering of above composite nanofibers. All kinds of fibers were characterized by TG, EDS, FTIR, XRD, FE-SEM, and so on .The results the surface of the fibers sintered became rough and the average diameter of fibers decreased more than half when compared to PVP/Zn(CH₃COO)₂/Fe(NO₃)₃ composite nanofibers. And with the sintering temperature increasing, the average diameter of fibers firstly decresed and then increased slightly. With the sintering temperature increasing, the intensity of diffraction peak became stronger, and the diffraction peak became more sharp, it indicated the crystallization of the remaining sample after sintering was getting better. The photocatalytic properties of nanofibers sintered under different conditions had been studied, such as when sintering at different temperature and different zinc acetate and copper nitrate complex mass ratio. When the composite fibers of zinc acetate and copper nitrate complex mass ratio being ₂0:1 was sintered at 700°C, we found the photocatalytic efficiencies of the remaining sample at this point were proved to be the highest by monitoring the photodegradation of methylene blue. It was equal to photocatalytic efficiencies of ZnO nanofibers. Been used once as a catalyst to reuse, it was found ZnO/Fe₃O₄ nanofibers had a good photocatalytic properties. Therefore, ZnO/Fe₃O₄ nanofibers had good photocatalytic properties and also had a good reuse performance.(3) PVP/Zn(CH₃COO)₂/Cu(NO₃)₂ composite nanofibers were prepared by electrospinning, and ZnO/CuO composite nanofibers were obtained by high temperature sintering of above composite nanofibers. All kinds of fibers were characterized by TG, EDS, FTIR, XRD, FE-SEM, and so on. The photocatalytic properties of ZnO/CuO composite nanofibers had been studied. When the composite fibers of zinc acetate and copper nitrate complex mass ratio being ₂0:1 was sintered at 700°C, it was found the photocatalytic efficiencies of the remaining sample at this point were proved to be the highest by monitoring the photodegradation of methylene blue. However, when compared with pure ZnO nanofibers, its photocatalytic effciencies decreased a bit.