Synthesis and Characterization of Pt-Sn-Pd/C Catalysts for Ethanol Electro-Oxidation Reaction

Carbon-supported Pt-Sn-Pd electrocatalysts have been synthesized by conventional borohydride reduction method and characterized for ethanol electro-oxidation reaction. Energy dispersive spectroscopy (EDS), thermogravimetry analysis (TGA), and transmission electron microscopy (TEM) analysis reveal that the synthesized catalysts are composed of uniformly dispersed metal nanoparticles on Vulcan XC-72R with the intended compositions. However X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) data reveal that the degree of alloying with Sn is very low and most of the Sn may exist as oxide phases. The electrochemical properties of the catalysts with 40 wt.% metal on carbon have been evaluated by cyclic voltammetry (CV), chronoamperometry, and electrochemical impedance spectroscopy (EIS). The catalytic activity for ethanol electro-oxidation reaction decreases in the order Pt-Sn-Pd (1:0.75:0.25) > Pt-Sn-Pd (1:0.5:0.5) > Pt-Sn (1:1). An analysis of the electrochemical data suggests that the tin oxide phase has a promoting effect on the ethanol electro-oxidation reaction and the incorporation of a low amount of Pd to Pt-Sn further enhances the activity for ethanol electro-oxidation.