Poly(aniline-co-p-phenylenediamine)- Ag /Platinum-Modified Pencil Graphite Electrode for the Electorocatalytic Oxidation of Methanol

Direct alcohol fuel cells (DAFCs) are promising power sources for the portable electric vehicles and variety of applications, due to their high energy efficiency and environmental benign nature. Pt catalysts for the methanol oxidation reaction have attracted a great deal of attention because they are key part of the anode in direct methanol fule cells (DMFCs) [1]. However, the low electrocatalytic activity and short-term stability of these catalysts in the methanol electrooxidation still prevent the widespread commercialization of DMFC. To develop cost effective electrodes, it has been shown that the dispersion of Pt in very minute quantities in the form of microparticles inside a polymer matrix lead to obtain modified electrodes which represent excellent electrocatalytic properties for the oxidation of methanol[2]. Such properties can attributed to (i) an increase in active surface area by dispersion of the catalyst and (ii) a better utilization of Pt crystallites in decreasing the poisoning effects of carbon monoxide [3]. In the current study new poly(aniline- co-n-phenylenediamine)-Ag nanocomposits polymers were synthesized via emulsion polymerization. The synthesized nanocomposits polymers were use to modification of the pencil graphite electrods for the efficient electrooxidation of methanol in acidic media. The pencil graphite electrod modified with nanocomposit polymer poly(aniline-co-p-phenylenediamine)-Ag and Pt nanoparticles showed excellent efficiency for the electrocatalytic oxidation of methanol. The nanocomposit-Ag-Pt electrod modifier was then characterized by (FT-IR), X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The electrocatalytic performance of the modified pencil graphite electrodes have been evaluated by cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) techniques. Several experimental parameters that affect on the electrodes response such as the cycle numbers, type and concentration of acidic media, amount of nanocomposite and concentration of platinum were investigated. It was concluded that the obtained modified pencil graphite electrode under optimal condition can apply for efficient electrocatalytic oxidation of methanol with high stability without affecting under poisoning.