Preparation Of Functionalized Carbon Composite And Application In Electrochemical Analysis

Carbon materials such as graphene,carbon nanotubes,carbon nanofibers,biomass porous carbon and carbon nanoribbon and et al.have a variety of morphologies and structures,which are widely used in supercapacitor,catalytic carrier,lithium battery,electrochemistry and other fields.Various preparation methods can be used to synthesize carbon based composites.This paper focuses on the preparation of four kinds of carbon nanocomposites including hydroxyapatite doped carbon nanofibers composite materials（HAp@CNF）,gold nanoparticles electrodeposition seaweed derived biomass carbon（AuNPs@SDBC）,gold microparticles doped alocasia stem porous carbon（Au@APC）and gold platinum bimetallic decorated mushroom biomass porous carbon（Au-Pt@BPC）.Based on those carbon materials modified electrodes,this study investigated the electrical catalytic behavior of redox proteins and drug molecules detection.The thesis mainly includes the following four parts:1.HAp@CNF modified carbon ionic liquid electrode（CILE）was prepared and used for the investigation on direct electrochemistry and electrocatalysis of myoglobin（Mb）.HAp nanoparticles were mixed with polyacrylonitrile（PAN）solution and HAp@PAN nanofiber was synthesized by electrospining process,which was further controlled carbonization at 800℃for 2h in nitrogen atmosphere to get HAp@CNF nanocomposite.Various techniques were used to check the physicochemical properties of HAp@CNF.Mb was mixed with HAp@CNF dispersion solution and casted on the surface of CILE to obtain an electrochemical sensing platform.Direct electrochemistry of Mb on the modified electrode was checked with a pair of enhanced redox waves appeared on cyclic voltammogram,indicating the direct electron transfer of Mb.HAp@CNF exhibited high conductivity,good biocompatibility and large surface area,which was benefited for the Mb immobilization and electron transfer.The modified electrode showed excellent electrocatalytic activity towards the reduction of trichloroacetic acid（TCA）and sodium nitrite（NaNO₂）,which was further used to establish a new electroanalytical detection method.Real samples were analyzed by the proposed method with satisfactory results.2.Seaweed derived biomass carbon（SDBC）was synthesized by a high temperature pyrolysis method.Gold nanoparticles（AuNPs）was electrodeposited on the surface of SDBC/CILE to fabricate AuNPs@SDBC/CILE.The surface morphology of AuNPs@SDBC/CILE was investigated by SEM.And the modified electrode was applied to investigate the electrochemical behaviors of rutin by cyclic voltammetry in pH4.0 PBS.The influence of pH and scan rate was further investigated with electron transfer coefficient（α）and the electrode reaction rate constant（k_s）obtained as 0.48 and 1.7 s^-1,respectively.At the same time,the linear relationship between rutin concentration and oxidation peak current was investigated by differential pulse voltammetry（DPV）and the lowest detection limit was 0.051μmol L^-1.3.An electrochemical detection platform（Au@APC/CILE）with Au@APC modified CILE was prepared and applied to study the electrochemical behavior of rutin.The structure and morphology of APC and Au@APC were characterized by SEM and TEM.The results showed a loose and pore structure of APC after special treatment,which provided effective surface area for reduction of HAuCl₄ into Au particles.The electrochemical behavior of rutin on Au@APC/CILE was investigated by cyclic voltammetry in pH 2.0 phosphate buffer solution and a pair of reversible redox peaks were obtained with the number of transferred electrons（n）as 2.1,the electron transfer coefficient（α）as 0.65,and the electrode reaction rate constant（k_s）as1.23 s^-1.The linear relationship between different concentrations of rutin and the corresponding oxidation peak current was further explored in the detection range from0.12 to 120 mol L^-1,and the limit of detection was 0.0265μmol L^-1.Blood samples was detected by this method with recovery calculated from the standard addition method.4.Au-Pt@BPC was synthesized by carbonization of oyster mushroom and solvothermal method,which was applied in the electrode modification and electrochemical detection of baicalein.The structural and elemental data of Au-Pt@BPC were analyzed by XPS,SEM,TEM and Raman spectrum.The Au-Pt@BPC modified CILE was prepared as working electrode for the detection of baicalein,which exhibited a pair of redox peak on cyclic voltammograms with enhanced peak currents.The results proved the positive effects of the composite including the high conductivity of biometal,the catalytic activity of noble metal and the large-surface of porous carbon with excellent adsorption ability.Under the optimal conditions the oxidation peak currents of baicalein were linear with its concentration in0.48-140μmol L^-1via differential pulse voltammetry,and the limit of detection was calculated as 0.010μmol L^-1.The modified electrode was successfully applied for the detection of baicalein in real drug sample.Meanwhile,the low cost and facile preparation of oyster mushroom based BPC made it become a potential substrate electrode material.