| Chemically modified electrodes (CMEs) and electrochemical sensors are one of the active research areas in modern electrochemistry and electroanalytical chemistry. Among various of modified materials used to fabricate chemically modified electrodes, polynuclear metal hexacyanoferrates have been extensive studies for the applications in electrocatalysis, electrochemical sensors, functional materials, electrochromism, molecular sieves, solid-state batteries and molecular magnetism due to their good chemical and electrochemical stability, profuse electrochemical activities. Based on the reasons mentioned above, my dissertation mainly aimed at the exploitation of new polynuclear metal hexacyanoferrates and improvement their analytical performance in electrochemical sensors fields. The electrochemical and electrocatalytic activity of PB, CuHCF, SnHCF, GaHCF, ZrHCF were investigated by fabricating their modified sol-gel derived carbon paste electrode and carbon paste electrode. On the other hand, five kinds of rare earth metal hexacyanoferrates including LaHCF, CeHCF, PrHCF, ErHCF, and TbHCF were synthesized and their spectroscopic, electrochemical characterization and electrocatalytic activity were also investigated carefully in this dissertation. Based on the above investigation results, methods of amperometric determination of H2O2, L-Cys, D-glucose, AA, and hydrazine were also established in my research work.The main contributions of this dissertation were summarized as follows:1. A new type of Prussian blue modified sol-gel derived carbon ceramic compositeelectrode was fabricated by using cyclic voltammetry from the single K3Fe(CN)6solution in the presence of HAuCl4. The electrochemical and electrocatalytic activityof this modified electrode were investigated carefully. The experimental results showed that a compact and uniform PB nanocluster film was formed quickly on the CCE surface during the potential sweeps. This PB modified electrode had strongly electrocatalytic activity toward the reduction of H2O2 in pH 7.0 PBS. Under the optimum conditions, a linear dependence of the catalytic current versus H2O2 concentration was obtained in the range of 1.0×10-6 to 5.0×10-3 mol·L-1 with a detection limit of 5.0×10-7 mol·L-1, and a sensitivity of 28.6μA·(mmol·L-1)-1.2. The nano gold-particle dispersed in chitosan solution was synthesized from the hybrid solution of HAuCl4 and chitosan by using one step procedure. A new type of amperometric glucose biosensor base on the Nafion-CS-Gox-AuNPs hybrid film was fabricated by using sandwich configuration on the surface of PB-modified carbon ceramic composite electrode. The effects of experimental conditions on the analytical performance of this biosensor were investigated carefully. Under the optimum conditions, a linear dependence of the catalytic current versus the concentration of glucose was obtained in the range of 1.0×10-5 to 2.5×10-3 mol·L-1 with a detection limit of 5.0×10-6 mol·L-1, and a sensitivity of S.SSμA·(mmol·L-1)-1. The apparent Michaelis-Menten constant Km and the response time were 3.96×10-3 mol·L-1 and 5 s, respectively. The biosensor was successfully applied to determine the glucose concentration in human serum samples. Compared to other biosensors reported previously, this glucose biosensor exhibited high sensitivity, good stability, fast response time, good operational stability and anti-interferent ability.3. The gallium hexacyanoferrate and zirconium hexacyanoferrate were synthesized by co-deposition method and characterized by FTIR, XRD, and XPS techniques. Their electrochemical behavior and electrocatalytic activities were studied by fabricating Nafion/ZrHCF/CPE and Nafion/GaHCF/CPE chemically modified electrode. The experimental results showed that these two metal hexacyaoferrates exhibited strongly electrocatalytic activity toward the reduction of H2O2 in pH 7.0 base solution. The heterogeneous catalytic reaction rate constants determined by chronoamperometry were 0.799×103 L·mol-1·s-1 for ZrHCF and 3.13×103 L·mol-1·s-1 for GaHCF, respectively. Under the optimum conditions, a linear dependence of the catalytic current versus H2O2 concentration ware obtained in the range of 1.0×10-6 to 8.0×10-4 mol·L-1 for ZrHCF and 5.0×10-6 to 5.0×10-4 mol·L-1 for GaHCF with the detection limit of 5×10-7 mol·L-1 and 1×10-6 mol·L-1, respectively. The sensitivity of the modified electrodes toward H2O2 were 25.2μA·(mmol·L-1)-1 and 27.9μA·(mmol·L-1)-1, respectively. Compared to other metal hexacyanoferrates modified electrodes used to determine the concentration of H2O2, the virtue of my present work was the dramatic decrease of over-potential for the reduction of H2O2 in netrual medium, the operating potential of amperometric determination were 0.10 V vs. SCE, thus must be benefit for the selectivity of the determination of H2O2. Additionally, the simplicity for the preparation and the easy surface renew of the modified electrodes were also useful in the practical applications.4. Five kinds of lanthanide rare earth metal hexacyanoferrates of LaHCF, CeHCF, PrHCF, TbHCF and ErHCF were synthesized with the use of co-deposition method. Their spectroscopic characterizations were characterized by FTIR, XRD, XPS and SEM techniques. Furthermore, the electrochemical behavior and electrocatalytic activities of these metal hexacyanoferrates were studied carefully by fabricating of LaHCF/CPE, CeHCF/CPE, PrHCF/CPE, TbHCF/CCE and ErHCF/CCE chemically modified electrodes. The experimental results showed that all these five kind of rare earth metal hexacyanoferrates exhibited one pair of redox waves located at the low-potential region with the formal potential about 0.2 V vs. SCE on the cyclic voltammagramms. The LaHCF/CPE, ErHCF/CCE, and TbHCF/CCE had strong electrocatalytic activity toward the oxidation of AA, L-Cys, while the PrHCF/CPE had the electrocatalytic activity toward the reduction of H2O2. The heterogeneous catalytic reaction rate constants to AA and L-Cys determined by chronoamperometry were 2.55×103 for LaHCF, 4.0×103 for ErHCF, and 2.71×103 L·mol-1·s-1 for TbHCF, respectively. Under the optimum conditions, a linear dependence of the catalytic current versus AA or L-Cys concentration were obtained in the range of 5.0×10-6 to 5.0×10-4 for ErHCF, 5.0×10-7 to 1.0×10-4 for TbHCF, and 5.0×10-6 to 2.0×10-3 mol·L-1 for LaHCF with the detection limit of 2×10-6, 2×10-7, and 8×10-7 mol·L-1, respectively. The sensitivity of the modified electrodes were 34.2, 138.8, and 38.8μA-(mmol·L)-1, respectively.5. Two kinds of transition metal hexacyanoferrates of CuHCF and SnHCF modified sol-gel derived carbon ceramic composite electrodes were constructed by two-step sol-gel and mechanically attachment methods, respectively. The analytical performances toward hydrazine and sodium sulfite of these two types of chemically modified electrodes were investigated carefully. Under optimum conditions, a linear dependence of the catalytic current versus the concentration of hydrazine and sodium sulfite were obtained in the range of 3.0×10-6 to 7.5×10-3 and 8.0×10-6 to 4.0×10-4 mol·L-1, respectively. The detection limit were 8×10-7 and 3×10-6 mol·L-1, respectively. The sensitivity were 14.9 and 118.2μA·(mmol·L-1)-1, respectively. The simplicity for the preparation and the easy surface renew of the modified electrodes were useful in the practical applications.
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