Ethanol Electro-oxidation on Pt/C Electrocatalysts: An "In Situ" Raman Spectroelectrochemical Study

This work presents an "in situ" spectroelectrochemical study of the ethanol oxidation reaction on Pt/C electrocatalysts prepared by the polymeric precursor method. Characterization of the electrocatalysts was performed with X-ray diffraction, Raman spectroscopy, and cyclic voltammetry measurements. The average crystallite size was estimated as 7 nm, in agreement with the value reported in the literature for these types of electrocatalysts. The cyclic voltammetry characterization in an acidic medium presented the expected voltammetric behavior for polycrystalline Pt/C. The ethanol oxidation process was successfully employed "in situ", making use of an optical probe for excitation and collection of the Raman scattering signal. In this configuration it was possible to track the formation of the main products CO, CO2 indirectly, acetaldehyde, and acetic acid-and to measure the decay of the ethanol concentration. The results indicate that the optical probe-based Raman spectroscopy technique is a very effective tool for studying "in situ" electrochemical oxidation reactions of ethanol. It might also be a very promising characterization technique for studies of the "in situ" electrochemical oxidation of small organic molecules.