Preparation and Characterization of Pd Nanoparticles Supported on Graphene-Based Anode Catalysts for Direct Methanol Fuel Cells

Abstract

Palladium (Pd) nanoparticles supported by graphene nanomaterials were prepared and tested in this work using methanol as the fuel. The synthesized nanoparticles were used as electrocatalysts for direct methanol fuel cell. The support materials were synthesized by modified Hummer’s method and subsequently doped with nitrogen using melamine. The electrocatalysts were synthesized using modified polyol method. The synthesis method of the electrocatalyst was further modified by adjusting the pH of the electrocatalyst from 12 to 13. The structural characterization of the support materials was carried out using Fourier Transform Infrared (FT-IR) spectroscopy and Brunauer-Emmett-Teller (BET) technique while that of the electrocatalysts was also done using X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM). The elemental analysis was carried out using energy dispersive spectroscopy (EDS) to validated the presence of N-doped in Nitrogen-doped graphene oxide (NGO) and NrGO support materials and the Pd loading. The electroactivity, electron kinetics and stability of the electrocatalyst towards methanol oxidation were evaluated using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA) respectively. The results showed that the modification of electrocatalyst by increasing the pH to 13 did not improve the activity of the electrocatalyst generally since the supported Pd catalysts synthesized by modified polyol method exhibited better electroactivity towards methanol oxidation than their pH 13 counterparts.