Synthetic core–shell Ni@Pd nanoparticles supported on graphene and used as an advanced nanoelectrocatalyst for methanol oxidation

Abstract

In this study, the uniform dispersion of new highly active Ni@Pd core–shell nanoparticle catalysts supported on graphene (Ni@Pd/graphene) was prepared via a two-step procedure involving a microwave synthesis method and a replacement method. Several characterization tools, such as X-ray powder diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) were employed to study the phase structures, morphologies and properties of the Ni@Pd/graphene composite. The results indicated that a uniform dispersion of Ni@Pd core–shell structure nanoparticles on graphene have an average particle size of 4 nm. The Ni@Pd/graphene composite was used as an electrocatalyst for alcohol oxidation in alkaline media for fuel cells. The electrocatalytic activity of Ni@Pd/graphene for ethanol oxidation is 3 times higher than that of the Pd/graphene electrocatalyst at the same Pd loading. The enhanced electrocatalytic properties could be attributed not only to the electric synergistic effect between Pd, Ni and graphene, but also the high use ratio of Pd due to its shell structure.