The burgeoning demand for clean and energy-efficient fuel cell system requires electrocatalysts to deliver greater activity and selectivity. Bimetallic catalysts have proven superior to single metal catalysts in this respect. This work reports the preparation, characterization, and electrocatalytic characteristics of a new bimetallic nanocatalyst. The catalyst, Pt-Au-graphene, was synthesized by electrodeposition of Pt-Au nanostructures on the surface of graphene sheets, and characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray powder diffraction (XRD), and voltammetry. The morphology and composition of the nanocatalyst can be easily controlled by adjusting the molar ratio between Pt and Au precursors. The electrocatalytic characteristics of the nanocatalysts for the oxygen reduction reaction (ORR) and the methanol oxidation reaction (MOR) were systematically investigated by cyclic voltammetry. The Pt-Au-graphene catalysts exhibits higher catalytic activity than Au-graphene and Pt-graphene catalysts for both the ORR and the MOR, and the highest activity is obtained at a Pt/Au molar ratio of 2:1. Moreover, graphene can significantly enhance the long-term stability of the nanocatalyst toward the MOR by effectively removing the accumulated carbonaceous species formed in the oxidation of methanol from the surface of the catalyst. Therefore, this work has demonstrated that a higher performance of ORR and the MOR could be realized at the Pt-Au-graphene electrocatalyst while Pt utilization also could be greatly diminished. This method may open a general approach for the morphology-controlled synthesis of bimetallic Pt-M nanocatalysts, which can be expected to have promising applications in fuel cells.

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Three-dimensional Pd@Pt core−shell nanostructures with controllable shape and composition were synthesized by using a one-step microwave heating method. The nanostructures with the morphology, structure, and composition being easily controlled through adjusting the molar ratio between Pt and Pd precursor were characterized by transmission electronic microscopy (TEM), scanning electronic microscopy (SEM), X-ray powder diffraction (XRD), and energy-dispersive X-ray (EDX) techniques. In addition, the electrocatalytic characteristics of these prepared Pd@Pt electrocatalysts with different Pd/Pt molar ratio for oxygen electro-reduction reaction (ORR) and methanol electro-oxidation reaction (MOR) were systematically investigated by voltammetry. The results show that Pd@Pt electrocatalysts exhibit higher catalytic activity than pure Pd and pure Pt catalysts for both the ORR and MOR, and the highest activity is obtained at the Pd@Pt electrocatalyst with a Pd/Pt molar ratio of 1:3. This result demonstrates that a higher performance of ORR and MOR could be realized at the novel core−shell electrocatalyst while Pt utilization also could be diminished. This method may open a general approach for the shape-controlled synthesis of bimetallic Pt−M nanocatalysts, which can be expected to have promising applications in fuel cells.