Iridium-based catalysts for the ethanol electrooxidation in acidic media

Abstract

Herein we sinthesize and investigate Ir-based nanocatalysts (dispersed in carbon) in different atomic compositions combining two (IrRh) and three metals (IrRhSn). These materials were evaluated towards the ethanol electrooxidation in acidic electrolyte in presence of three ethanol concentrations using cyclic voltammetry, while the species produced during the reaction were monitored by in situ Fourier transform infrared spectroscopy (FTIR). Results show that IrRh binary electrocatalysts are selective to the production of CO2 from ethanol, but the catalytic activity is poor. This finding is interpreted in terms of a slow adsorption of ethanol that is assumed to be the rate determining step during the electrooxidation of the alcohol. Ternary catalysts, in turn, present higher electrooxidation currents and anticipate the production of CO2. However, the selectivity towards the CO2 pathway is lost and the higher catalityc activity is justified by a growing production of acetic acid, illustrating the influence of Sn on the eletrooxidation of ethanol.