N-doped graphene-supported Pt and Pt-Ru nanoparticles with high electrocatalytic activity for methanol oxidation

In this work, Pt and Pt-Ru nanoparticles were synthesized on both graphene and nitrogen (N)-doped graphene sheets, and their effects on electrocatalytic activity for methanol oxidation were investigated using cyclic voltammetry and electrochemical impedance spectroscopy. Experimental results show that, in comparison to pure graphene as catalyst support, N-doped graphene-supported Pt and Pt-Ru nanoparticles demonstrate enhanced characteristics for methanol electro-oxidations with regard to oxidation potential, forward peak oxidation current density, and charge transfer resistance. For instance, the forward peak current densities of graphene-supported Pt and Pt-Ru nanoparticles were 9.5 mA/cm² and 7.3 mA/cm², respectively; however, the current densities of N-doped graphene-supported Pt and Pt-Ru nanoparticles were 19.9 mA/cm² and 16.2 mA/cm², respectively. The doping of nitrogen into graphene can effectively improve the currently density by twice. Our findings suggest the use of N-doped graphene sheets as promising catalyst supports for direct methanol fuel cells.