Electrochemistry and electrocatalytic activity of polypyrrole/ferrocyanide films on a glassy carbon electrode

Functionalized polypyrrole films were pre pared by incorporation of Fe(CN)(6)(3-) as doping anion during the electropolymerization of pyrrole at a glassy carbon electrode from aqueous solution. The electrochemical behavior of the Fe(CN)(6)(3-)/Fe(CN)(6)(4-) redox couple in polypyrrole was studied by cyclic voltammetry. An obvious surface redox reaction was observed and dependence of this reaction on the solution pH was illustrated. The electrocatalytic ability of polypyrrole film with ferrocyanide incorporated was demonstrated by oxidation of ascorbic acid at the optimized pH of 4 in a glycine buffer. The catalytic effect for mediated oxidation of ascorbic acid was 300 mV and the bimolecular rate constant determined for surface coverage of 4.5 x 10(-8) M cm(-2) using rotating disk electrode voltammetry was 86 M-1 s(-1). Furthermore, the catalytic oxidation current was linearly dependent on ascorbic acid concentration in the range 5 x 10(-4)-1.6 x 10(-2) M with a correlation coefficient of 0.996. The plot of i(p) versus nu(1/2) confirms the diffusion nature of the peak current i(p).