The electrocatalytic oxidation of ascorbic acid on polyaniline film synthesized in the presence of ferrocenesulfonic acid

The catalytic oxidation of ascorbic acid on the two kinds of polyaniline electrodes (PAn and PAnFc films) has been carried out by cyclic voltammetry, constant potential and constant current methods. PAnFc and PAn films were synthesized in the presence and absence of ferrocenesulfonic acid, respectively. For the electrolysis of ascorbic acid at pH 5.64, the anodic peak potential of ascorbic acid shifts from 0.32 V (vs. SCE) on the bare platinum electrode to 0.05 V on both PAn and PAnFc electrodes. The oxidation current of ascorbic acid on the PAnFc electrode is 31 times as high as on the bare platinum electrode at the electrolysis of the constant potential. The exchange current density is 1.3 mA cm−2 on the PAnFc electrode and 1.0 mA cm−2 on the PAn electrode. The catalytic effect is caused by polyaniline itself. Ferrocenesulfonic acid doped in polyaniline plays an important role in enhancing the catalytic activity of polyaniline in the solution of pH >5.