Electrochemical Sensing Analysis Based On Three-Dimensional Kenaf Stem-Derived Porous Carbon Integrated Electrodes

Electrochemical sensor is a kind of device which combines the concentration change of measured component with electrochemical signal and provides real-time information of chemical component in the detected system by using electrochemical principle.This kind of sensor has the advantages of high sensitivity,choice,fast analysis speed,simple operation,easy miniaturization and on-line detection.It is a difficult problem to improve the repeatability of the electrode compared with the traditional electrochemical sensor.In this thesis,we use three-Dimensional porous carbon electrode based on kenaf stem-derived,and combine with different materials to construct electrochemical sensor,which can be used to detect ascorbic acid,glucose and hydrogen peroxide.The main works included the following three parts:1.In this work,a ratio ascorbic acid electrochemical sensor was constructed by using a one-step method of direct immobilization of thionine?Thi?with a three-dimensional porous carbon derived from kenaf stem?3D-KSC?.The treated3D-KSC and 3D-KSC electrodes are characterized by scanning electron microscopy?SEM?and energy dispersive spectroscopy?EDS?.By characterization,we can see that the surface of 3D-KSC is smooth and there are some micropores.It is because of these defects that our small molecule Thi can be attached to the 3D-KSC,which makes the immobilization of Thi more solid.3D-KSC/Thi material can catalyzes ascorbic acid at 0.015 V,while the oxidation peak of Thi at-0.24v does not change with the increase of ascorbic acid concentration.Using the ratio of peak current density of these two oxidation peaks,a ratio of ascorbic acid electrochemical sensor was designed.The linear range of the surface of ascorbic acid electrochemical sensor is 18.22?M-8 mM and the detection limit is 5.99?M.2.This work builds a novel enzyme-free glucose sensor by growing copper oxide nanoparticles?CuNPs@Carbon?and gold nanoparticles?AuNPs?composites on three-dimensional porous carbon?3D-KSC?.Firstly,the 3D-KSC is made by the high temperature carbonization of hemp rod.Then,through the hydrothermal method on the growth of Cu-BTC,and then the nitrogen atmosphere under high temperature calcination of 3D-KSC/CuNPs@Carbon.Finally,the target material3D-KSC/CuO@Carbon/AuNPs nano-composites was formed by redox reaction between 3D-KSC/CuNPs@Carbon and HAuCl₄.The nano-composites can be prepareddirectlyintooneelectrode.Themorphologyof3D-KSC/CuO@Carbon/AuNPs nano-composites was investigated by scanning electronmicroscopy,andtheelectrochemicalpropertiesofthe3D-KSC/CuO@Carbon/AuNPs electrode were tested by electrochemical technique and the electrocatalytic performance of the glucose was investigated.The experimental results show that the linear range of glucose electrochemical sensors based on 3D-KSC/CuO@Carbon/AuNPs-one electrode is 37.1?M–8.5 m M,the detection limit is 12.2?M and the sensitivity is 0.935 mA cm^-22 mM^-1.3.In this work,we use the covalent organic frameworks?COF?grown on three-dimensional porous carbon?3D-KSC?to prepare 3D-KSC/COF_TAPB-PDAAPB-PDA integrated electrode for constructing highly sensitive enzyme free electrochemical sensor.The layered COF is uniformly distributed on the pore wall of 3D-KSC,which increases the effective specific surface area of 3D-KSC.The spherical CuNPs and PtNPs are deposited directly on the 3D-KSC/COF_TAPB-PDAAPB-PDA electrode by electrostatic potential deposition.The electrochemical behavior,electrocatalytic oxidation of glucoseandelectrocatalyticreductionofhydrogenperoxideat3D-KSC/COF_TAPB-PDA/CuNPs and 3D-KSC/COF_TAPB-PDA/Pt NPs integrated electrodes were studied by cyclic voltammetry,electrochemical impedance method and chronoamperometric method.The results showed that the linear range of glucose detection by 3D-KSC/COF_TAPB-PDA/CuNPs integrated electrode is 4.69?M-7.07 mM and the detection limit is 1.54?M.The linear range of the detection of hydrogen peroxide by 3D-KSC/COF_TAPB-PDA/PtNPs integrated electrode is 0.0185?M-3055.4?M,and the detection limit is 0.006?M.The selectivity,repeatability and stability of the two sensors are also studied.The results show that they have strong selectivity,good repeatability and good stability.