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The aim of this work is to synthesize polypyrrole (PPy) films on nonconducting cellulosic substrate and modified by copper oxide particles for use in the nitrate electroreduction process. Firstly, the chemical polymerization of polypyrrole onto cellulosic substrate is conducted by using 3 as an oxidant and pyrrole as monomer. The thickness and topography of the different PPy films obtained were estimated using a profilometer apparatus. The electrochemical reactivity of the obtained electrodes was tested by voltamperometry technique and electrochemical impedance spectroscopy. Secondly, the modification of the PPy film surface by incorporation of copper oxide particles is conducted by applying a galvanostatic procedure from a 2 solution. The SEM, EDX and XRD analysis showed the presence of particles in the polymer films with dimensions less than 50 nm. From cyclic voltamperometry experiments, the composite activity for the nitrate electroreduction reaction was evaluated and the peak of nitrate reduction is found to vary linearly with initial nitrate concentration. [ABSTRACT FROM AUTHOR]

Abstract: A polypyrrole containing ferrocyanide ions Fe(CN)6 3− (FCN) as doping anions were prepared by anodic electropolymerization onto iron and onto thermally pre-treated iron electrodes, in an aqueous solution containing pyrrole, potassium hexacyanoferrate (K4Fe(CN)6) and potassium tetraoxalate (C4H3KO8). The electrochemical behaviour of these modified electrodes was studied by cyclic voltammetry method. The electrostatic ability of these modified electrodes (PPy/FCN/Fe and PPy/FCN/Fe3O4/Fe) was demonstrated towards the oxidation of ascorbic acid (H2A). The results show that Fe(CN)6 3− anions incorporated into the PPy matrix improve the electrocatalytic activity of these films. The (PPy/FCN/Fe3O4/Fe) modified electrode showed greater ability and redox electroactivity than the (PPy/FCN/Fe) modified electrode and than the unmodified Fe electrode. It has been found that under optimum pH condition (pH 7), the oxidation of ascorbic acid at the surface of PPy/FCN/Fe3O4/Fe occurs at a potential about 200mV less positive than at PPy/FCN/Fe and at Fe surfaces. The catalytic oxidation peak current showed a linear dependence on the ascorbic acid concentration and a linear calibration curve was obtained in the range 0.5–9mM of ascorbic acid with a correlation coefficient of 0.9994 and good sensitivity (0.24μA/μM). The detection limit (2σ) was determined and found to be equal to 0.15mM. [Copyright &y& Elsevier]