FTIR in situ investigations during the electrocatalytic oxidation of ethanol on PtSn/CeOsub(2)-C

Abstract

Pt-Sn/C and PtSn/CeO2-C electrocatalyst were prepared in a single step by an alcohol-reduction process using ethylene glycol as solvent and reducing agent and CeO2 (15 wt%) and Vulcan XC72 (85 wt%) as supports. The performance for ethanol oxidation was investigated by cyclic voltammetry and in situ FTIR spectroscopy. Highest current densities were achieved by the PtSn/CeO2-C catalysts. FTIR results showed that the presence of CeO2 on PtSn/C catalyst favors the C-C break bond leading to a higher ratio [CO2]/[H3CCOOH] of products during ethanol oxidation (Figure 1). The carbonyl band is hardly seen in the PtSn/CeO2-C catalyst and its intensity increases in the order PtSn/CeO2-C < PtSn/C < Pt/CeO2-C. A large positive band about 1650 cm-1 which is attributed to the vibration δ(HOH) of interfacial water decreases in the same order. The positive effect of CeO2 addition in PtSn catalyst can be due the synergetic effect between Pt, SnO2 and CeO2. It favors not only the bifunctional mechanism but also the break of C-C bond in the adsorbed acetaldehyde molecule.