Preparation And Application Of Ferrocene Bridge Polysilsesquioxanes Modified Electrodes

Ferrocene bridged polysilsesquioxanes is a novel ferrocene detivatives. Chemical modified electrode which prepared by this polymer has high stability, good reproducibility. Morever, to a certain extent, we can get high-performance chemically modified electrode easily by introduction of other species or control the reaction conditions in the sol-gel process.In this thesis, We used a novel bridged monomer,(EtO)3Si-C2H4-Fc-C2H4-Si(OEt)3 (1,1'-bis[(2-triethoxylsilyl)ethyl]ferrocene, BTEF), to fabricate a series of GCE via sol-gel process. The sols were obtained respectively by co-hydrolysis of BTEF with TEOS and co-hydrolysis of BTEF with poly(vinylalcohol) (PVA). We optimized the preparation conditions and studied the electrochemical characteristics of the two modified electrodes by cyclic voltammetry (CV) method. In particular, we optimized the determination conditions of ascorbic acid(H2A), such as the scan rates v, system pH, etc.,and explored the mechanism of electrocatalytic reaction. The two ferrocene modified electrodes were shown excellent electrocatalytic response. The related exploration will laid an important foundation for the further application in practice.The research results were as follows:1.The type of catalyst has an influnce on the performance of BTEF/TEOS/GCE. The mild catalyst is benefit of getting a better reversible and stable modified electrode than the acid or alkali catalyst. The results shown that optimized catalyst for the preparation of BTEF/TEOS/GCE is NH4F.2.PVA has played a role of stabilizer and dispersion in the sol process. Adding a right amount of PVA, we can get uniform size of colloidal particles and pore size. The results shown that optimized dosage for BTEF/PVA/GCE is 300μL(Vtotal=10 mL).3.The ion size and valence of the supportting electrolyte have an influnce on the reversible and stable properties of BTEF/TEOS/GCE and BTEF/PVA/GCE. The results indecating that the optimized supporting electrolyte in aqueous solution is NaC104.4.The scan rates has a significant influnce on the two modified electrodes.The result shown that for BTEF/PVA/GCE,at the scan rate between 10 and 1000 mVs-1,a diffusion-controlled process plays the leading role in the charge transfer process. However, for BTEF/TEOS/GCE, at lower scan rates (between 10 and 100 mVs-1),a surface process plays the dominant role, while, at higher scan rates (between 100 and 1000 mVs-1) the charge transport process occurs mainly by a diffusion-controlled process.5.After successive 50 time's cyclic voltammetric, there is no peak potential shift, and the peak current of BTEF/PVA/GCE and BTEF/TEOS/GCE only decreased 5.58%,4.95% respectively, and the electrochemical reversibility of the ferrocene modified electrodes are not affected. Noteworthily, all the experiments were conducted under aerobic conditions. The results indicate that the ferrocene bridged polysilsesquioxanes films have good stability in aqueous.6. pH is an important factor in the oxidation of H2A. Firstly, pH can influnce the existence forms of H2A. Secondly, pH also has an influnce on the electrochemical performance of the two modified electrodes.It is well-known that chemically modified electrodes for analytical purpose must meet two conditions,①can reduce the overpotential of the substrate, the interference and background current;②can increase the current response, reducing the detection limit. The results suggest that the two modified electrodes all have a better electrocatalytic oxidation effect on H2A in 0.1 mol·L-1 NaClO4 phosphate buffer solution at pH=8.0.