Synthesis Of New Graphene-based And Carbon Nanotube-based Composites And Their Applications In Electrochemical Sensing

Carbon nanomaterials are widely concerned by electrochemical workers because of their large specific surface area,high electrical conductivity,electron mobility and mechanical properties.At the same time,carbon nanomaterials also have a wide electrochemical window,strong electrochemical stability and high electrocatalytic activity.Therefore,carbon nanomaterials represented by graphene are of great concern in electrochemical sensor applications,such as carbon nanotubes(CNT),oxide graphene(GO),reduced oxide grachene(RGO)and nitrogen-doped graphene(NGR).The main ways to enhance the application of carbon nanomaterials in electrochemistry are: on the one hand,the band structure of graphene can be controlled by atomic doping,such as nitrogen-doped graphene.On the other hand,carbon nanomaterials are also improved by their compatibility with other functional materials to improve their dispersibility and processability to improve their electrocatalytic activity and electrochemical selectivity.With the preparation of macro carbon nanomaterials and the functionalization of carbon nanomaterials,carbon nanomaterials based binary composites have become a hotspot in various fields.This paper is based on carbon nanomaterials preparation of composite materials by CuFeO2,Co3O4 and ferrocene derivatives.The aim of this study is to improve the electron transfer rate and the stability of inorganic materials,and to construct a new type of electrochemistry by using the synergistic effect with carbon nanomaterials and the electrocatalytic activity of dopamine,uric acid,ascorbic acid and nitrite ion were studied.This paper summarizes the preparation methods,functional methods,application of graphene and its composites in different fields in recent years.The main part of the thesis contains the following three aspects:(1)Synthesis of CuFeO2@RGO and CuFeO2@NGR composites by using graphene and nitrogen doped graphene as raw materials,and construction of a new electrochemical sensor to detect nitrite ions.The novel composites CuFeO2@RGO and CuFeO2@NGR were prepared by simple solvothermal method with GO as the base,and the synthesis method was further optimized to construct a new electrochemical sensor to detect nitrite ions.The results show that the new composite materials of CuFeO2@NGR synthesized with NGR to be stronger electrocatalytic ability for NO2-than that of single material.At the same time,the composite has good electrochemical performance for nitrite ions: wide linearity range,low detection limit and high sensitivity.On the other hand,the newcomposite CuFeO2/RGO modified glassy carbon electrode was synthesized by using graphene as raw material.The results show that the composite has better electrocatalytic effect than single material,the nitrite concentration and peak current showed good linearity between 0.1 ?M and 100 ?M,also had low detection limit(0.03 ?M,S/N = 3)with good selectivity,reproducibility and stability.In addition,the use of two kinds of modified electrodes for the measurement of biomolecules in the actual samples has achieved satisfactory results.The excellent performance of the two modified electrodes is mainly due to the synergistic effect between the carbon material and CuFeO2.(2)Synthesis of Co3O4NPs/RGO based on graphene oxide and construction of a novel electrochemical sensor for the detection of nitrite ions.Synthesis of new Co3O4 NPs/RGO nanocomposites by hydrothermal method and detection of nitrite.The results of cyclic voltammetry showed that the catalytic activity of Co3O4 NPs/RGO/GCE was about 7.6 times higher than that of Co3O4 NPs/GCE and bare electrode.The experimental results show that Co3O4 NPs/RGO/GCE exhibits good electrochemical performance for nitrite ion: wide linear range(0.1 ?M-67.7 ?M),low detection limit(0.03 ?M,S/N=3)and high sensitivity(27.4 ?A · mM-1).The excellent performance of the modified electrode is mainly due to the increase of the catalytic activity and stability of Co3O4 NPs with large specific surface area.At the same time,the synergistic effect between graphene and Co3O4 improves the catalytic effect.In addition,the use of the modified electrode for the measurement of biomolecules in the actual sample also yielded satisfactory results.(3)Synthesis of Carbon Nanotube composites Based on Functionalized Ferrocene,as new type of electrochemical sensor to detect dopamine,ascorbic acid and uric acid.Amine functionalized MWNTs and graphene(GO)were synthesized and characterized by IR,X-ray powder diffraction,energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy.And the important neurotransmission neurotransmitters in the human body were analyzed by cyclic voltammetry(CV)and differential pulse voltammetry(DPV).Ferrocene(Fc)has good conductivity,electrochemical stability and reversible redox couple,combined with aminated MWNTs and GO by amide bond showed good electrocatalytic performance in simultaneous detection of ascorbic acid(AA),dopamine(DA)and uric acid(UA),which showed good electrocatalytic performance,compared with a single materialcatalytic effect is the best.The results of DPV test showed that the peak separation between AA,DA and UA was high,and the peak potential was-170 mV,35 mV and180 mV,respectively.Therefore,FcA-MWNTs can be used as the modified electrode to detect the three kinds of analytes of AA,DA and UA.The modified electrode has not only good stability,repeatability,selectivity and fast response rate,but also applied to success of human serum,urine and other real samples of the test.