Study On The Electrochemical Preparation And Property Of Ferrocene Derivatives Doping Polyaniline

Two kinds of ferrocene derivatives doping polyaniline, the ferrocenyl ethanol doping polyaniline and the disubstituted ferrocenyl carboxylic acid doping polyaniline, were sysnthesized by electrochemical method in this paper. Then,they were used to modify ITO electrode. The preparation, structural and electrochemical performance of polyaniline doped with ferrocene derivatives, the applications of modified electrodes to quantitative determinate ascorbic acid and to catalytic reduce p-nitrophenol(PNP), were studied. The main achievements of the work can be summarized as follows:1.Ferrocene was used as a raw material to obtain single and double substituted acetyl ferrocene by Friedel-Crafts acylation, then reduced to ferrocenyl ethanol and oxidized to disubstituted ferrocenyl carboxylic acid. Two kinds of ITO electrodes modified with ferrocene derivatives doping polyanilines were prepared by electrochemical. The optimum preparation conditions are as follows: concentration of sulfuric acid is 0.6 mol/L, concentration of aniline is 0.05mol/L, concentration of ferrocene derivatives is 1.4×10-4 mol/L, scanning laps of 12 and scanning speed of50mV/s. TGA shows that the PANI-Fc(COOH)2 contains 6.11% Fe and the PANI-Fc CH2OHCH3 contains 7.02% Fe. SEM indicates that the molecular chains like a three-dimensional network structure. The electrons could pass rapidly between molecular chains, which facilitate the redox reaction of Fe2+/Fe3+. TEM shows that the size distribution of Fe nanoparticles in PANI-FcCH2OHCH3 is wide, about5~30nm; while the size distribution of Fe nanoparticles in PANI-Fc(COOH)2 is more uniform, about 10 nm.2.The CV test shows that the redox peak currents of ferrocene derivatives doping polyaniline are larger than pure polyaniline. Meaning that the conductivity of doped polyaniline is better than pure polyaniline. Fe2+in the ferrocene plays a role in electronic transmission. Corresponding to three pairs of reversible redox peaks,the color could interconverse between light green、emerald green、emerald blue andpurple by changing the applied voltage. The doped polyaniline still has electrical activity at alkaline medium which significantly broadening the electrochromic pH range of polyaniline. Modified electrode surface diffusion coefficient of ferrocenyl ethanol doping polyaniline is 4.91 × 10-6cm2/s and disubstituted ferrocenyl acid doping polyaniline is 3.88×10-5 cm2/s by chronoamperometry. The electrochemical properties of PANI-Fc(COOH)2 are better than PANI-FcCH2OHCH3.3.The ferrocene derivatives doping polyanilines(ITO) were used to electrochemically detect ascorbic acid(AA). The feasibility of ITO electrodes was discussed.When the concentration of AA in the range of 1×10-4mol/L~1×10-7 mol/L,the concentration of AA has a good linear relationship with the oxidation peak current, which could be used for drawing the calibration curve of AA. The lowest detection limits are 1.82×10-7mol/L and 2.36×10-7mol/L. The catalytic process is controlled by diffusion. The modified electrodes have good anti-interference,stability and reproducibility(RSD=1.32%, 0.71%). The lowest detection limit and reproducibility of PANI-Fc(COOH)2 are better than PANI-FcCH2OHCH3.4.Two kinds of ITO electrodes modified with ferrocene derivatives doping polyanilines were used to the catalytic reduction of p-nitrophenol through UV-vis.The catalytic rate constant K was calculated. The results suggest that the ITO modified electrodes catalyze the complete reduction of PNP to PAP within 5min when the applied voltage is 0.9V. The catalytic efficiency of PANI-Fc(COOH)2 is better than PANI-FcCH2OHCH3.