The total ethanol electro-oxidation to produce CO2 and H2O, involves the transfer of 12 electrons per molecule. This has been conducted to a great interest in its applications as fuel in convertor devices such as fuel cells. In order to generate CO2, it is necessary breaking the C-H e C-C bonds, and the CO-O bond formation. In acid electrolyte, on Pt-based electrocatalysts, the reaction follows parallel pathways producing acetic acid and acetaldehyde, but CO2 is produced only in a minor extent, which reduces the fuel cell efficiency. In alkaline electrolyte, the presence of adsorbed oxygenated species on the electrocatalyst surface, at low electrochemical potentials, facilitates the oxidation of the reaction intermediates, but still presents little efficiency for the total oxidation to CO2. So, it is necessary to further advance in the knowledge of the reaction mechanism, and in the development of electrocatalysts that produces the selective oxidation of the ethanol molecules to CO2. Among the different materials studied in order to increase the oxidation efficiency in acid electrolyte as, for example, bimetallic nanoparticles composed by Pt-M (M = Ru, Rh, Sn, Mo and etc), only the combination of Pt with Rh has been shown a favoring of the oxidation of ethanol following the direct pathway and, in the alkaline environment, promising activities have been obtained in Pd-based materials. Therefore, this work aims to further advance in the study of the mechanism and in the development of more active electrocatalyts for the oxidation of ethanol. The electrocatalysts will be composed by carbon-supported Rh and Pd nanoparticles, and by different nanostructures obtained by the combination of Rh and Pt atoms, in the case of acid electrolyte, and Pd and Pt, in the case of alkaline electrolyte. The reaction pathways followed on the different nanoparticles will be studied by in situ FTIR (Fourier Transform Infra-red) and by on line DEMS (Differential Electrochemical Mass Spectrometry), associated with electrochemical techniques, such as cyclic voltammetry and cronoamperometry.
News published in Agência FAPESP Newsletter about the scholarship: