Structural Design,preparation And Application Of Electrospinning Nanofibers Materials

In recent years,electrospinning nanofibers have been widely studied because of their high aspect ratio,large specific surface area,controllable structure and diverse morphology.Graphene aerogels have also attracted attention due to high porosity,high surface area,low density and good compressibility.In this paper,the structure design and surface treatment of electrospinning nanofibers are studied,and the surface modified nanofibers are used as reinforcement materials.Functional nanofibers with Janus structure were not only prepared,but also surface modified electrospinning nanofibers were used as reinforcing materials to prepare nanofibers/graphene aerogels.Specific research contents are as follows.(1)CoOx/C nanofibers with Janus structure were prepared by electrospinning technology and heat treatment process,combined with needle design.The effects of electrospinning parameters and heat treatment temperature on the morphology,structure and composition of nanofibers with Janus structure were discussed.The prepared CoOx/C Janus nanofibers were used for oxygen reduction catalysis,and their catalytic activities were tested.The experimental results show that the optimal preparation conditions are:10 wt%PAN/DMF solution,14 wt%PVP/DMF solution,metal salt concentration is 30%of PVP,and the electrospinning process parameters are:receiving distance is 15 cm,electrospinning voltage is 17 kV,electrospinning solution flow rate is 0.002 mL min-1,pre-oxidation temperature is 260?,and carbonization temperature is 800?.The obtained CoOx/C Janus nano fibers have obvious Janus structure and have obvious electrocatalytic activity for oxygen reduction.(2)Combining electrospinning,hydrothermal and freeze-drying methods,one-dimensional nanofibers and two-dimensional graphene nanosheets were selected as raw materials to prepare nanofibers/graphene hybrid aerogels.The effects of the concentration of graphene oxide solution,reducing agents,hydrothermal reaction temperature and time on structure of nanofibers/graphene hybrid aerogels were explored.The experimental results show that the optimal experimental conditions are a graphene oxide concentration is 3 mg mL-1,ascorbic acid as the reducing agent,a mass ratio of nano fibers to graphene oxide is 1:1,a hydrothermal reaction temperature is 90? and the reaction time is 6 hours,and the prepared nanofibers/graphene hybrid aerogel has a hierarchical microstructure of 'layered structure+pore structure+nanofiber'.(3)The nanofibers/graphene hybrid aerogels were used as piezoresistive sensors to test their mechanical properties and piezoresistive sensing properties.The test results showed that the compressive strength of the hybrid aerogel is up to 43.54 kPa,which is higher than that of pure graphene aerogel,the piezoresistance is good,the hybrid aerogel can rebound quickly after compression,and the signal response is fast(up to 37 ms),having a linear sensitivity and it an monitor pulse and vocal cord vibration,finger joints,wrist and knee movements.