Synthesis and electrochemical characterization of Graphene-Polyallylamine Nanocomposites as a New Supports of Pt Catalyst for Direct Methanol Fuel Cell Application

In this research, nanocomposites of Platinum Graphene-Polyallylamine (Pt/PAA/GNP) were developed to increase the methanol electro-oxidation activity and stability of commercial Pt/C electrocatalyst. After the synthesis process, graphene oxide was functionalized with Polyallylamine via the cross linking approach, then Pt as a catalyst was dispersed on the as prepared support by a novel process, which is a polyol synthesis method assisted by microwaves. X-ray diffraction (XRD) results showed that Pt particles, with a mean particle size of about 6.17 , were dispersed on the support. FESEM images showed that the Pt nanoparticles were successfully dispersed on the functionalized graphene nanoplates. Based on the electrochemical properties characterized by cyclic voltammetry (CV), including CO stripping measurements, it was found that the prepared Pt/PAA/GNP electrocatalyst exhibited a comparable activity for methanol oxidation reaction with respect to the commercial one. A significant reduction in the potential of the CO electro-oxidation peak from 0.93V for the Pt/C to 0.89 V for the Pt/PAA/GNP electrocatalyst indicates that there was a significant increase in the CO electro-oxidation activity, which is achieved by replacing the voulcan. Also, the as prepared Pt/PAA/GNP electrocatalyst exhibits high catalytic activity for the MOR in terms of electrochemical surface with respect to Pt/C (40.53 vs 17.61 m2/mgPt ), which may be attributed to structural changes caused by the high specific surface area of the PAA modified graphene nanoplates catalyst support. Moreover, chronoamerometry results showed that in the presence of methanol, the Pt/PAA/GNP electrocatalyst still maintains a higher current density than Pt/C.