PAN/BiOI Composite Nanofibers:Preparation And Photocatalytic Properties

Semiconductor photocatalytic technology is a hot topic in materials science due to its potential applications in solving the global problems such as environmental pollution and energy shortage.The series materials of BiOX(X=Cl,Br,I)have become the rising star in the field of photocatalytic research because of their special layered crystal structures and suitable energy band structures.Among the series of BiOX,Bi OI has been widely concerned due to its excellent visible light catalytic properties and better visible light utilizations.BiOI nanostructures have high specific surface areas and good photocatalytic activities.However,these nanostructures suspended in the liquid are very easy to reunite the lower catalytic activity.Moreover,it is difficult to separate these catalysts from liquid and recycling,which also reduces their practical usability.In order to solve these problems,we design to immobilize Bi OI nano structures on the surface of good carrier with high specific surface area and macrostructure to improve the dispersion and recycling performance of catalysts.Electrospun polyacrylonitrile(PAN)nanofibers may be excellent carriers for BiOI nanostructures due to their high specific surface area,three-dimensional macroporous structural characteristics,good flexibility and chemical stability.In this dissertation,flexible PAN/BiOI nanofiber composites with both high specific surface area and macroporous structures were prepared by using electrospinning technique and solvothermal synthesis method.These nanofibers composite were characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray diffraction(XRD).Systematic studies were performed on the reaction time,precursor concentration,the contents of carrier and the preparation methods of carrier,and their effects on the fiber morphology and structure influence.For the carrier of PAN/Bi(NO3)3 nanofibers,the growth process of BiOI nanostructures were discussed.And the photocatalytic properties of PAN/BiOI nanofiber composites were also measured.The results show that:(1)the introduction of PAN nanofiber template can significantly improve the dispersion of BiOI nanostructures;reducing the reaction time and reaction concentration would result lower and uneven loading of BiOI nanostructures on the carrier surface,while BiOI would agglomerate at high precursor concentration and longer reaction time;(2)compared to the pure PAN and PAN/KI nanofibers,the distribution of BiOI is more uniform for the carriers of PAN/Bi(NO3)3nanofibers;the mixture of ethylene glycol and water has no effect on the formation of BiOI,but will affect the flexibility of the nanofiber composite;(3)the interaction between bismuth ions and PAN is influenced by the preparation route of the PAN/Bi(NO3)3 nanofibers,whichalso affects the position and the growth process of BiOI nanostructures;BiOI nanostructures are grown on the surface and inside of PAN nanofibers for weak and strong interactions,respectively;(4)the PAN/BiOI nanofiber composites exhibit good photocatalytic properties,and can effectively degrade methyl orange dye under visible light illumination.