Highly Active Graphene-Supported Ni_<i>x</i>Pd_{100–<i>x</i>}Binary Alloyed Catalysts for Electro-Oxidation of Ethanol in an Alkaline Media

Abstract

A series of graphene (G)-supported Ni x Pd 100– x binary alloyed catalysts (BACs) were prepared with variation of Ni and Pd metal loading through a facile chemical reduction method and were used as an anode catalyst for ethanol oxidation reaction (EOR), which is superior fuels for direct ethanol fuel cells (DEFCs). The X-ray diffraction (XRD) data reveals that the Ni x Pd 100– x /G catalysts were homogeneously alloyed, and Ni was present with the oxidized form. The transmission electron microscopy (TEM) images also suggest the alloyed formation with different shapes of metal nanoparticles (NPs). The electrochemical properties of the catalysts were evaluated using cyclic voltammetry (CV) and chronoamperometry (CA) in 1 M KOH electrolyte. The higher catalytic activity for EOR was increased in the order Ni 75 Pd 25 /G > Ni 0 Pd 100 /G > Ni 25 Pd 75 /G > Ni 50 Pd 50 /G. Among Ni x Pd 100– x /G BACs, the Ni 50 Pd 50 /G catalyst showed the highest onset potential (−0.8 V) on CV and long-term stability on amperometric measurements. The overall parameters of EOR study were determined that the Ni 50 Pd 50 /G was more favorable in various ethanol (EtOH) concentrations and scan rate.