Application of Ti/RuO 2–Ta 2O 5 electrodes in the electrooxidation of ethanol and derivants: Reactivity versus electrocatalytic efficiency

Abstract

The influence of the preparation method on the performance of RuO 2–Ta 2O 5 electrodes was evaluated toward the ethanol oxidation reaction (EOR). Freshly prepared RuO 2–Ta 2O 5 thin films containing between 30 and 80 at.% Ru were prepared by two different methods: the modified Pechini–Adams method (DPP) and standard thermal decomposition (STD). Electrochemical investigation of the electrode containing RuO 2–Ta 2O 5 thin films was conducted as a function of electrode composition in a 0.5-mol dm −3 H 2SO 4 solution, in the presence and absence of ethanol and its derivants (acetaldehyde and acetic acid). At a low ethanol concentration (5 mmol dm −3), ethanol oxidation leads to high yields of acetic acid and CO 2. On the other hand, an increase in ethanol concentration (15–1000 mmol dm −3) favors acetaldehyde formation, so acetic acid and CO 2 production is hindered, in this case. Electrodes prepared by DPP provide higher current efficiency than STD electrodes for all the investigated ethanol concentrations. This may be explained by the increase in electrode area obtained with the DPP preparation method compared with STD.