Methanol electro-oxidation on Pt/PGE modified by poly (aniline-co-pphenylenediamine)- Ni nanocomposites

Direct methanol fuel cell has a significant advantage for powering portable applications due to its simple design, low operating temperature, and convenient fuel storage and supply. Methanol is also attractive low cost liquid fuel which is widely available, easy for handling, storage, and refueling. It has high energy density similar to gasoline. 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 attribute to the increasing of active surface area by dispersion of the catalyst and also a lowering of Pt crystallites poisoning carbon monoxide [3]. In the present study, in order to achieve an inexpensive tolerable anode catalyst for direct methanol fuel cell applications, a nanocomposites of poly(aniline-co-p-phenylendiamine)-Ni and Pt nanoparticles (PANI-co-Ppda)@Ni/Pt), was prepared by in-situ emulsion polymerization. The synthesized nanocomposites was used to modify pencil graphite electrode (PGE) and the capability of the obtained modified electrode in methanol electrooxidation was investigated. The efficience of the modified electrode was studied by different electrochemical methods such as; cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronoamperometry and the results were compared with those obtained by the bare Pt/PGE. The electrode modifier was 14th Annual Electrochemistry Seminar of Iran Materials and Energy Research Center (MERC), 12- 13 Dec, 2018 196 characterized by FT-IR, X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). FESEM images are indicated that (PANI-co-Ppda)@Ni/Pt/PGE) make good juctions between platinum particles and anchor the platinum particles and so reduce the Pt migration during methanol electrooxidation. The obtained results reveal that the introduction of nanocomposites within catalyst layer improved the catalytic activity of the Pt nanoparticles.