Effect of Mo addition on the electrocatalytic activity of Pt–Sn–Mo/C for direct ethanol fuel cells

Abstract

Carbon-supported Pt–Sn–Mo electrocatalysts have been synthesized by a polyol reduction method and characterized for ethanol electro-oxidation reaction (EOR). While the percent loading of the synthesized nanoparticles on the carbon support is higher than 35%, energy dispersive spectroscopy (EDS) reveals that the Mo contents in the nanoparticle catalysts are lower than the nominal value, indicating incomplete reduction of the Mo precursor. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analyses reveal that the Sn and Mo exist as oxide phases at the surface layers of the nanoparticles and the degree of alloying is very low. The electrochemical properties of the electrocatalysts have been evaluated by cyclic voltammetry (CV) and chronoamperometry. The catalytic activity for EOR decreases in the order PtSnMo 0.6/C > PtSnMo 0.4/C > PtSn/C. Single cell direct ethanol fuel cell (DEFC) tests also confirm that the PtSnMo 0.6/C anode catalyst exhibit better performance than the PtSn/C anode catalyst. An analysis of the electrochemical data suggests that the incorporation of Mo to Pt–Sn enhances further the catalytic activity for EOR.