Fabrication Of Electrospun Nanofiber-based Catalytic Materials And The Study Of Their Properties

Electrospinning technology is a simple and verstile method for fabricationnanofibers, which has attracted more and more attention in recent years. Because ofits excellent, chemical, physical properties and its high surface area, high porosity,process control, electrospun nanofibers can be used as base material in many areassuch as catalysts, sensors, biological and pharmaceutical fields. Especially in the fieldof catalysis, the high specific surface area of electrospun nanofibers makes them goodcandidates as supports for nanocatalysts. In the field of noble metal catalysis area, Pd,Au, Pt are very expensive thus it is necessary to improve their catalytic activity andrecycle performance. Not only in the term of the specific surface area electrospinningnanofiber has big advantage but also the recovery of electrospinning nanofibers is alsovery good. It’s easy to control and separate the catalyst from the reaction system. Theelectrospinning nanofiber has extensive application in the field of photocatalyticoxidation, electro catalysis, enzyme catalysis, and chemical catalysis etc.Nanocomposites are materials that composed of two or more component, at leastone of them is in the nano-scale. Nanocomposites can achieve the function which thesingle one can not achieve and meet the demand of the modern society. Nowadays,there are many methods for fabricating nanocomposite material, these methods aremainly through multistep process, so how to prepare nanocomposite material simplyis still a challenge to solve.In this thesis, by using electrospinning nanofibers as the base material, and through one-step preparation we fabricated a variety of composite catalytic nanofibermaterials, expecting to get prominent catalytic properties and good-recyclingcomposites nanomaterial. The experimental results are as follows:1. CoFe2O4/Polypyrrole (PPy)/Pd ternary composite nanofibers are fabricatedthrough a one-step redox reaction between pyrrole and Na2PdCl4in the presence ofelectrospun CoFe2O4nanofibers in ethylene glycol (EG). PPy is formed on the surfaceof electrospun CoFe2O4nanofibers. The Pd nanoparticles with diameters of about2–6nm are dispersed in the PPy matrix. The CoFe2O4/Polypyrrole (PPy)/Pd ternarycomposite nanofibers exhibit good catalytic activity toward the reduction ofp-nitrophenol. The rate constant kappis about13.2×10-3s-1. The as preparedCoFe2O4/Polypyrrole (PPy)/Pd ternary composite nanofibers have good magneticproperty and easy to recycle. The average conversion rate of circulation is99.2%，89.7%and65.1%, respectively.2. We use PAN nanofiber as the base material and prepared Pd/PPy/PANcomposite nanofiber membrane successfully. The generation of Pd nanoparticles withaverage diameter of about5nm is accompanied by the formation of PPy on thesurface of electrospun PAN nanofiber membrane. XRD demonstrates the formationand the good crystallinity of the supported Pd NPs. The as-prepared Pd/PPy/PANnanofiber membrane exhibited good catalytic performance towards hydrogengeneration from the hydrolysis of ammonia borane (AB). By changing the reactiontemperature, we get the apparent activation energy (Ea). The result shows that the Eawas calculated to be about33.5kJ/mol, which is much lower than the report before. Itshows no decrease in catalytic reactivity in five successive runs. The membraneremains good morphology and palladium nanoparticles aggregation slightly.3. We use PAN nanofiber as the base material to prepare Fe2V4O13/PANcomposite nanofiber membrane. Nanoflake Fe2V4O13was grown on the surface ofPAN nanofiber. And we test the catalytic performance of degradation of methyleneblue dye in the presence of H2O2. The result shows that the rate of the degradation ofmethylene blue dye is93.5%, and75.7%after the fourth time. The nanofibermembrane remains good morphology after fourth time. This indicated the Fe2V4O13/PAN membrane we fabricated possesses good fenton-like property andrecycling property.