The Study Of Preparation And Application Of Functional Carbon Nanofibers

The chemically modified electrode can accelerate the electron transfer rate,improve the selectivity and enhance the electrocatalytic activity of the substance to be tested,which make it have advantages in improving the selectivity and sensitivity of the detection method.The combination of chemically modified electrode and electrochemical detection can combine the specific reaction of modified material with the sensitivity of detection method,which can make enrichment,determination and separation into one system.Carbon nanofibers（CNF）have attracted more and more attention due to their advantages of good corrosion resistance,good conductivity and high porosity.Functional modified CNF have become excellent electrode modified materials due to their larger specific surface area and a large number of functional groups.In this paper,different functional modification methods are used to modify the CNF obtained by electrospinning in order to obtain composite CNF with different functional characteristics.The morphology,structure and element composition of the composite materials are characterized by field emission scanning electron microscopy（SEM）,X-ray photoelectron spectroscopy（XPS）,Raman spectroscopy（Raman）,X-ray diffraction（XRD）,specific surface and porosity analyzer（BET）and the application of these materials in the field of chemically modified electrode is explored,the main content are as follows:1.A three-dimensional carbon nanofiber network was formed by first electrospinning a mixed solution of montmorillonite（MMT）and polyacrylonitrile（PAN）,and then carbonizing the composite nanofiber and etching it with hydrofluoric acid.The form and morphology of the nanofibers were analyzed by scanning electron microscopy（SEM）,Raman microspectroscopy（Raman）,and X-ray photoelectron spectroscopy（XPS）.The sensor fabricated on three-dimensional carbon nanofiber showed a good linear response（y=0.076x-0.110,R²=0.999,and y=0.193x-1.770,R²=0.998）,high stability and selectivity,and a low detection limit(0.4μg·L^-1)for Cu²⁺as measured using differential pulse voltammetry under the optimal conditions,and the method mentioned above was also used to analyze Cu²⁺in real tap water samples,which had good recoveries.2.A novel electrochemiluminescence（ECL）sensor for the simple and effective detection of difenidol hydrochloride was fabricated by modifying a glassy carbon electrode with three-dimensional carbon nanofibers（3D-CNFs）.The 3D-CNFs were synthesized by electrospinning a mixture of montmorillonite（MMT）and polyacrylonitrile,carbonizing the electrospun product,and etching it with hydrofluoric acid.According to the experimental results obtained using the modified electrodes,a good linear relationship was found between peak intensity and difenidol concentration（y=868.14x-61.04,R²=0.999）,with a relatively low detection limit(8.64×10^-10mol·L^-1（S/N=3）).In addition,our approach exhibited good recovery values ranging from 98.99%to 102.28%.The proposed novel ECL sensor has wide application prospects for the detection of difenidol hydrochloride.3.The carbon nanofibers with high specific surface area were prepared with polyacrylonitrile（PAN）as spinning precursor by electrospinning.A new method for the determination of azithromycin by electrochemiluminescence was successfully established.The nanofibers were characterized by scanning electron microscopy（SEM）,Raman microspectroscopy（Raman）,and X-ray photoelectron spectroscopy（XPS）,X-ray diffraction（XRD）,and Micromeritics ASAP 2460 using the the Brunauer–Emmett–Teller（BET）equation.The results showed that the ECL intensity of the modified electrode is about 35 times than that of the bare electrode.Under the best experimental conditions,there is a good linear relationship between the concentration of azithromycin and the ECL intensity in the range of 8.0×10^-8-1.0×10^-4 mol·L^-1.The linear equation is y=108.60x+128.93（R²=0.999）,and the detection limit is 6.52×10^-8 mol·L^-1（S/N=3）.The recoveries of azithromycin capsule were 98.08%-101.76%.4.Nitrogen,phosphorus co-doped porous carbon nanofiber（N,P-PCNF）is prepared by electrospinning the mix solution of polyacrylonitrile（PAN）,polyvinylpyrrolidone（PVP）and phosphoric acid followed by carbonization.The N,P-PCNF as electrode modified material is directly used to fabricate an electrochemiluminescent sensor for determination of cyproheptadine,and owing to the large specific area,more active sites and promoting electron transfer,the sensor exhibits high electrocatalyic activity,high sensitivity,good linear relationship ranging from 1.0×10^-7 to 1.0×10^-5 mol L^-1 and low detection limit(2.89×10^-8 mol L^-1).In addition,the good recoveries of 99.35%-100.64%indicate that the sensor is promising application for the detection of cyproheptadine in real samples.