The electrocatalytic oxidation of gallic acid on polyaniline film synthesized in the presence of ferrocene phosphonic acid

The electrochemical oxidation of gallic acid on both PAn film electrode and PAnFc film electrode are performed by the cyclic voltammetry at the pH range 5.0-6.6. Polyanilines (PAn and PAnFc) are synthesized in the solution of phosphoric acid and the solution containing ferrocene phosphonic acid and phosphoric acid, respectively. The catalytic activity of the PAnFc film to gallic acid is better than that of the PAn film, and is dependent on pH value. The oxidation current of gallic acid on the PAnFc film electrode is 2.69 and 2.43 times as high as on the bare platinum electrode in the solution of 5 and 10 mM gallic acid, respectively, at pH 5.6. The anodic peak potential of gallic acid on the PAnFc film electrode shifts towards the negative direction, compared with that on the bare platinum electrode. The transfer coefficient, a, and the rate constant, K, for the electrochemical oxidation of gallic acid on the PAnFc film electrode, are determined at pH 5.0 to be 0.75 and 1.0 x 10(-3) s(-1), and at pH 5.6 to be 0.80 and 5.2 x 10(-3) s(-1), respectively, at 20 degreesC. (C) 2003 Elsevier Science B.V All rights reserved.