Electrooxidation of methanol and 2-propanol mixtures at platinum single crystal electrodes

In the present work the electrooxidation of methanol, 2-propanol and different mixtures of both alcohols has been studied on the three platinum basal planes in three different electrolytes (H2SO4, HClO4 and NaOH). The results indicate that, like in the case of both individual alcohols, the electrooxidation of the mixture is a structure sensitive reaction and that Pt(111) leads to higher current densities for some mixture compositions as compared to what could be expected from the contribution of the individual compounds. The effect of the methanol concentration in the mixture points out that 2-propanol is the main reacting fuel at the Pt(111) surface. Interestingly, the addition of methanol clearly has a positive effect on 2-propanol oxidation. For a specific mixture composition, while results from cyclic voltammetry indicate a modest twofold increase in current density, chronoamperometric results after 10 min experiment show a nearly 200 times higher current density. IR experiments have been performed to gain information about the enhancement mechanism. Nevertheless, we have found that both methanol and 2-propanol seem to follow the same mechanism as they follow in the absence of the other alcohol, and therefore the enhancement could be probably related to a competitive adsorption for the active surface sites. (C) 2009 Elsevier Ltd. All rights reserved.