Fabrication And Research Of Electrochemical Sensors Based On Novel Nanoscale Materials

Chemically modified electrode(CPEs) is constructed using molecules design and functional or artificial cut aimed on the electrode surface, so that the functional electrode surface structure can be achieved with intended effect. It has been widely applied in energy, life, environment, medicine and is widely used in information science and other fields. Nano-materials with small size, large specific surface area and unique features such as electronics, optics and heterogeneous catalysis, were widely employed as an ideal building material in the field of surface catalysis, drug delivery, molecular recognition, environmental monitoring, chemical and biological sensing. As a currently hot issue, nano-materials were widely used in electrochemical sensor. More and more researchs focused on the construction of the nanoparticle functionalization interface especially in the field of photoelectric and chemical sensing, etc. Here, three kinds of modified electrodes were prepared by physical drops of coating and electrochemical methods, such as Mesoporous silicon foam modified carbon paste electrode(MCFs/CPE), Iron nickel cyanide-reduction of graphene oxide(Ni HCF/ERGO/GCE) and Iron cyanide nickel/cobalt-reduction of graphene oxide modified electrodes(Co/Ni HCF/ERGO/GCE). All the modified electrodes were characterized and evaluated using the scanning electron microscope(SEM), cyclic voltammetry(CV), differential pulse voltammetry(DPV), electrochemical impedance spectroscopy(EIS). The electrocatalysis process mechanism of three modified electrodes toward the target were investigated. In addition, the detection limit of the target and the stability and selectivity of the modified electrodes were also investigated. The details are described as follows:Chapter I: The preparation of mesoporous silica foam modified carbon paste electrode and its electrochemical oxidation toward capsaicinThe mesoporous silica foam modified carbon paste electrode(MCFs/CPE) was prepared via physical drops and coating method in this chapter. SEM, CV and EIS were successfully employed to characterize the modified electrodes. The electrochemical oxidation mechanisms of the prepared modified electrode toward capsaicin were investigated using the CV and DPV. With large specific surface area and high adsorption performance of MCFs, the proposed modified electrode shows high sensitivity towards the oxidation of capsaicin. Under optimized conditions, the electrochemical oxidation current of capsaicin was found to be linearly related to the concentration over the range 7.6×10-7~1.17×10-5 mol/L, and the detection limit was found to be 8.0×10-8 mol/L at a signal-to-noise ratio of 3. So a simple and rapid electrochemical determination method of capsaicin with high sensitivity and selectivity was established.Chapter II: An glucose sensor based on nickel hexacyanoferrate reduction of graphene oxideThe electrochemical reduction of graphene oxide modified glass carbon electrode(ERGO/GCE) was prepared via CV in this chapter. Then the nickel hexacyanoferrate were successfully prepared on the surface of ERGO/GCE by CV, and gained the Ni HCF/ERGO/GCE. SEM, CV and EIS were successfully employed to characterize the modified electrodes. The electrochemical oxidation mechanisms of the prepared modified electrode toward glucose were investigated using the CV and DPV. The proposed modified electrode shows high sensitivity towards the oxidation of glucose. The results showed that the apparent rate constant of glucose on the Ni HCF/REGO/GCE and Ni HCF/GCE is 271.62 and 34.92 M-1s-1, respectively. the detection limit was found to be 7.0×10-8 mol/L at a signal-to-noise ratio of 3. The sensor exhibits remarkable advantages, such as higher sensitivity and lower detection limit. The effective method has been proved to be a simple and rapid electrochemical determination method toward glucose.Chapter III: Electrochemical separation of ascorbic acid, dopamine and uric acid on nickel/cobalt hexacyanoferrate electrochemical reduction of graphene oxide electrodeThe electrochemical reduction of graphene oxide modified glass carbon electrode(ERGO/GCE) was prepared via CV in this chapter. Then the composites of nickel/cobalt hexacyanoferrate nanoparticles were successfully prepared on the surface of ERGO/GCE by CV, and gained the Co/Ni HCF/ERGO/GCE. SEM(EDS), CV and EIS were successfully employed to characterize the modified electrodes. The Electrochemical separation of ascorbic acid, dopamine and uric acid on the nickel/cobalt hexacyanoferrate-electrochemical reduction of graphene oxide electrode were investigated using the CV and DPV. The proposed modified electrode shows high sensitivity towards the electrochemical separation of ascorbic acid, dopamine and uric acid. The results showed that the peak to peak separation of three target is 248 m V(AA-DA)?136 m V(UA-DA) and 384 m V(AA-UA) on the prepared modified electrode, respectively. As can be seen, with the great specific surface area and unique geometrical structure of the composites, the modified surface showed a good oxidation catalytic activity toward overlapping voltammetric response of ascorbic acid, dopamine and uric acid. It is of great significance for the development and utilization of new electrochemical sensor toward ascorbic acid, dopamine and uric acid.