Ethanol oxidation reaction (EOR) investigation on Pt/C, Rh/C, and Pt-based bi- and tri-metallic electrocatalysts: A DEMS and in situ FTIR study

The ethanol oxidation reaction (EOR) was studied on Pt/C, Rh/C, Pt-Rh/C, Pt-SnO2/C and Pt-Rh-SnO2/C using on-line differential electrochemical mass spectrometry (DEMS) in a flow-cell system and in situ Fourier transform infrared spectroscopy (in situ FTIR). The electrocatalysts were synthesized by a modified polyol method and physically characterized by inductively-coupled plasma atomic emission spectroscopy (ICP-AES), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The electrocatalytic activity of the materials was tested for the EOR and the electrooxidation of a monolayer of adsorbed CO (COad being an intermediate of the EOR). Both in situ FTIR and DEMS investigations revealed that COad electrooxidation occurs at lower potentials on Pt-SnO2/C and Pt-Rh-SnO2/C than on Pt/C, Rh/C and Pt-Rh/C. A good correspondence was found between the (intensity vs. potential) variations of the m/z=22 mass-to-charge signal and of the IR band at 2343cm-1, both strictly assigned to CO2.