In the electro-oxidation reaction of alcohols, the understanding at the atomic level of interaction between the alcohol molecules and active sites of the catalyst is absolutely important for designing catalysts more tolerant with respect to the poisoning caused by strongly adsorbed intermediates species and, in addition, more selective towards the CO2 formation, which is the by product of highest energetic efficiency, or another product of high commercial value. This is extremely important to improve the application of Direct Alcohol Fuel Cells (DAFC) towards the cogeneration of electric energy and products of high commercial value. In this way, the present project aims to investigate the influence of electrode superficial structure to the mechanism of the electro-oxidation reaction of ethanol and glycerol, using model electrodes of Pt and Au (single crystals), very well-ordered (without surface defects) or disturbed (with random generated surface defects), in acid and alkaline aqueous medium. In the first step, will be used the cyclic voltammetry technique (potentiodynamic electroanalytical technique) to study the electrochemical behaviour of the oxidation of these alcohols (ethanol or glycerol) on well-ordered monocrystalline electrodes or on monocrystalline electrodes with random generated surface defects. In the second step, the identification and quantification of intermediates species and products of the oxidation reactions of ethanol and glycerol on these electrodes with different morphologies (geometry) of the surface atoms will be made. These identifications will be carried out, in situ, by applying potential to the working electrode, combining cyclic voltammetry or chronoamperometry with Fourier transform infrared spectroscopy (FTIR). In order to complement the FTIR analysis, further analysis will be made of the reaction products by using high performance liquid chromatography (HPLC) or ion chromatography (IC), after long term electrolysis at potentials determined from the voltammetric profiles of the alcohol oxidation. Finally the reaction mechanism will be proposed for these alcohols based on the results obtained.
News published in Agência FAPESP Newsletter about the scholarship: