Ethanol oxidation reactions using SnO2@Pt/C as an electrocatalyst

This paper presents a study on the ethanol oxidation reaction using SnO2@Pt/C core-shell structures as electrocatalysts. All the materials used, including Pt/C and PtSn/C E-tek, were 20% (w/w) metal on carbon. The formation of core-shell nanoparticles (SnO2@Pt/C) was measured by UV-vis spectrophotometry. X-ray diffraction measurements showed Pt (shell) diffraction patterns without influence from the SnO2 core and without any shift in 2 theta values for Pt. The diameters of the core-shell particle structures, measured using high-resolution transmission electron microscopy images, were in the range of 3-16 nm. The electrochemical profile for SnO2@Pt/C in an acidic medium (H2SO4 at a concentration of 0.5 mol L-1) was almost the same as the typical electrochemical behavior for Pt in an acidic medium. Furthermore, the onset potential for the ethanol oxidation reaction using SnO2@Pt/C was almost the same as that for PtSn/C E-tek (0.23 V versus the reversible hydrogen electrode). However, the mass current peak densities for ethanol oxidation were 50% higher on SnO2@Pt/C than on PtSn/C E-tek. In the polarization curve, the mass current density for ethanol oxidation was higher at all potentials for SnO2@Pt/C when compared to Pt/C and PtSn/C E-tek. At 0.5 V, the current mass density for ethanol oxidation on SnO2@Pt was 2.3 times of that for the same process on the commercial material. The electrocatalytic activity of SnO2@Pt/C for ethanol oxidation was associated with an increase in the electrochemically active surface area. However, an electronic effect should also be considered because the Pt shell changes its electronic structure in the presence of the foreign core. (C) 2010 Elsevier B.V. All rights reserved.