Preparation And Property Of One-Dimensional Nanocomposites Based On Natural Cotton Nanofibers

Because of the unique physical and chemical properties of nanomaterials, such asQuantum size effect, surface effect, small size effect, they have shown widelyapplication value in area such asphotocatalysis, photoelectricity, sensors, coating etc.The emergence of electrospinning technique provides a new world for obtainingnanomaterials energy-efficiently. At present, a lot of researches have extended to thefield of electrospinning. Cellulose, as an abundant renewable resource in nature, hasthe advantages of degradation, high biological activity and machinable. Its highlyprocessed products have been broadly applied in the industrialraw materials,biological medicine, environment, energysources, etc. The one-dimensionalnanomaterials obtained by electrospinning tehnique have many advantages such aslarge specific surface area, large length to diameter ratio, structural morphologydiversity, light quality, easy functionalization, which can provide a good carrierforinorganic nanometer functional materials, improve the stability of thenano-materials, prevent their reunion, control their size distribution. All theseadvantages make them to be a competing candidate in many important applications,suchas optical, electrical, magnetic, catalytic, even can product new singular function.This kind of composite materials “Mutually reinforcing”, sufficiently remedyinglimitation of single materials, canbring about a new situation of material design.In this thesis，we mainly discussed three parts of work of one-dimensionalnanocomposite preparation and performance research.1、Preparation and Property of Natural Cotton Cellulose/ZnO NanocompositesCotton cellulose nanofibers were obtained by Electrospinning process, theoptimized electrospining conditions as following1.15wt%cotton was added to8.5wt%LiCl/DMAc solution then magnetic stirring for4h at80°C. Typical spinning parameters were as follows: applied voltage was18kV; the collectordistance was15cm; humidity level was under40%; flowrate of the syringe pump was0.8ml/h; andthe electrospinning duration was12h at room temperature. Based on natural cottonfiber properties and electrospining process research, the improvements on theelectrospinning apparatus about preventing electrostatic interference and fiber reunionwere carried out, which were more suitable for the electrospinning. Becauseofone-dimensional nanomaterials obtained by electrospinning tehnique have manyadvantages such as large specific surface area, polyhydroxy, easily to modified,combining with hydrothermal methods, we successfully prepared ZnO nanorod arrayon the cotton fiber surface. The morphology and structure of composite nanofibers atdifferent experiment parameters were investigated. We also focused on the UVabsorption and photoluminescent properties of composite nanofibers at differenthydrothermal growth time.2、Preparation and Property of Natural Cotton Cellulose/ZnO/ZnS NanocompositesThe CC/ZnO nanorod array composite nanofibers were used as substrates forcreating CC/ZnO/ZnS core/shell composite nanofibers by hydrothermal method. Themorphology, structure, and properties of the composite nanofiber were analyzed bySEM, TEM, XRD, EDS, UV. The size of ZnS nanoparticles and the thickness of ZnSdeposited on the ZnO nanorods can control the concentration of thioacetamide duringhydrothermal reaction. The optimized structure have a maximum H2evolution with arate of445μmol·g-1·h-1. The ZnO/ZnS core/shell nanorod structure with n-pheterjunction plays an very important role in enhancing the photo absorption andincreasing surface areas, lifetime and yield of photogenerated charge carriers, whichare key factors contributing to a higher H2evolution rate.3、Preparation and Property of Natural Cotton Cellulose/TiO2NanocompositesThe electrospun CC nanofibers were used as substrates for preparing functionalcoating on the nanofiber surfaces by RF sputtering. The morphology and structure ofcomposite nanofibers at different sputtering power, different sputtering time,differernt sputtering pressure were investigated. The influence of ultravioletabsorption performance at different sputtering power was also studied. The cotton cellulose/TiO2composite nanofibers were characterized by the SEM, TEM, IR, EDS,and UV-vis. Results showed that the cotton cellulose surfure could been coated denseTiO2function thin film through RF sputtering. Furthermore, the UV test showed thatultraviolet absorption gradually increased along with the increase of sputtering power.