Synthesis and Characterization of Pd Nanocatalysts Based on N-Doped Graphene for Methanol Oxidation in PEM Fuel Cells

The Pt nanocatalysts are the most promising material in anodic catalysis for polymer exchange membrane fuel cells. The Achilles’ heel of these types of catalysis is the intense CO-poisoning that hinders the activation sites of the Pt-catalysis[1]. In these respects, the research efforts have been done to develop highly active and cost-effective new electrocatalyst. Two main factors that should be considered corresponding to them are: (i) the well-designed architect of nanoparticles on a structured substrate and (ii) advanced materials for the support [2]. Pd-catalysis is chosen as a cheaper substitute to oxidize methanol, decorated on N-doped graphene. Shifting the Fermi energy to a more positive level happens due to the substitution of N into graphene structure and the outcome is a better electronic conductivity. Utilization of urea as a nitrogen source and the hydrothermal method, helped the graphene oxide to have a hydrogel of NrGO. Impregnation of 20% Pd on this porous substrate resulted in Pd/NrGO. XRD analysis is a good evidence of different Pd facets, i.e. (111), (200) and (220) are related to 39.31⁰, 44.86⁰ and 66.47⁰ respectively. The cyclic voltammetry of this catalyst shows a great improvement in methanol oxidation in comparison to Pt/C. The onset peak of MOR in Pt/C is 1.0 V[3] while Pd/NrGO shifts it to 0.62 V and with consideration of commercial catalyst in mind, the synthesized catalyst increased If from 0.9 V[3] to 11.18 V.