Reduced Graphene Oxide-Magnetite for the Development of Highly Active, Selective and Methanol-Tolerant Pt Catalyst

This work reports a synthesis methodology for preparing a Pt catalyst supported in reduced graphene oxide (rGO), using magnetite (Fe₃O₄) as a strategy to decrease re-stacking layers of the rGO and improve the Pt catalytic activity during oxygen reduction reaction (ORR) and methanol tolerance effect. Pt nanoparticles supported on rGO-Fe₃O₄ were synthesized by chemical reduction and evaluated as cathode for the ORR. Pt nanoparticles with an average size of 4–5 nm were obtained, and XRD results give the guideline to affirm that Fe₃O₄ nanoparticles prevent to some extent the stacking effect in the rGO sheets that generally occur during the reduction process of GO. The catalytic evaluation demonstrates that ORR onto the Pt/rGO-Fe₃O₄ surface proceeds through a 4-electron transfer mechanism. The rGO-Fe₃O₄ support increases the specific catalytic activity of Pt at ≥ 0.84 V, which can be attributed to the electronic modification of Pt by Fe₃O₄ besides its high specific electrochemical surface area (27 m² g^− 1_Pt). The selectivity tests of Pt/rGO-Fe₃O₄ show a highly methanol tolerant material in terms of oxidation current densities and a slightly E_onset displacement of 20 mV.