Research On The Preparation And Photocatalytic Properties Of Composite TiO₂ Nanofibers By Centrifugal Spinning

In this thesis,TiO₂ nanofibers were prepared by centrifugal spinning combined with subsequent heat treatment process.By obtaining fibrous TiO₂,the recycling of TiO₂ was improved,and the reduction of photocatalytic efficiency due to the decrease of specific surface area was minimized.Firstly,the TiO₂ nanofibers with different diameters and morphologies were obtained by changing the mixing time of the solution,the ratio of raw materials,the centrifugal spinning parameters such as the rotation speed,and thus the preparation processing was optimized.On this basis,by adding silane coupling,carbon nitride?C₃N₄?and graphene oxide?GO?to modify the fiber,TiO₂ composite nanofibers with higher photocatalytic performance were obtained.Scanning electron microscopy,X-ray diffraction,Fourier infrared spectroscopy,diffuse reflectance spectroscopy and fluorescence spectroscopy were used to investigate the surface morphology,phase composition and molecular structure of TiO₂ composite nanofibers.The photocatalytic performance of the composite fiber was evaluated by the degradation experiments of rhodamine B.The results showed that N-Si-doped TiO₂ nanofibers,graphite-phase g-C₃N₄-TiO₂ composite nanofibers,and reduced-graphene-oxide RGO-TiO₂composite nanofibers have been successfully prepared.The diameter of the nanofiber increases with the decrease of the solution concentration and the decrease of the rotation speed.TiO₂ composite nanofibers exhibit good photocatalytic properties.Through the diffuse-reflectance spectrum and the fluorescence spectrum,the photoresponse range and intensity of the composite nanofiber were enhanced after the addition of the additive,as well the recombination rate of the photoelectron holes decreased,and therefore the photocatalytic performance was improved.Through the degradation experiments of Rhodamine B,it was proved that the photocatalytic performance of the doped fiber under UV light and visible light was improved,and the photocatalytic performance was the best when the amount of silane coupling agent was 2.5 wt%under ultraviolet light.As for the visible light conditions,the photocatalytic performance of the composite nanofiber was the best when the amount of silane coupling agent was 3.75 wt%.When the amount of C₃N₄ is 3.75wt%and 5wt%,the photocatalytic performance reaches the best under ultraviolet light and visible light conditions,respectively.Moreover,the photocatalytic properties of the composite nanofibers with additive of 5 wt%and 2.5 wt%GO possess the highest value in case of the UV condition and visible light condition,respectively.