Heteroatom-Doped Graphene-Supported Pt Nanoparticles as Electrocatalysts for Proton Exchange Membrane Fuel Cells

Platinum nanoparticles (PtNPs) are prepared from an aqueous H2PtCl6 solution using the sodium citrate method and supported on single-heteroatom-doped (S, N, and P) and dual-heteroatom-doped (N-S and N-P) graphene. The influence of the support of the electrocatalytic activity of PtNPs toward the oxygen reduction reaction (ORR) is investigated to assess their suitability as cathode materials for proton exchange membrane fuel cells (PEMFCs). Physical characterization of the catalysts proves that the PtNPs are evenly dispersed onto the heteroatom-doped graphene supports and maintain a size of 3-5 nm. The electrochemical results are obtained in a 0.1 M HClO4 electrolyte solution. The results show that the PtNPs supported on nitrogen and sulfur dual-heteroatom-doped graphene possess the highest specific activity (SA) of 2.44 mA cm(-2) at 0.9 V vs RHE, while the PtNPs supported on S-doped graphene show the lowest SA of 0.91 mA cm(-2). However, both SA values are well beyond that of PtNPs supported on Vulcan carbon (0.55 mA cm(-2)). Thus, the results obtained in this work confirm that doping the support that the PtNPs are attached to has a beneficial effect on the electrocatalytic activity toward ORR in acidic media.