Ethanol vs. glycerol: Understanding the lack of correlation between the oxidation currents and the production of CO2 on Pt nanoparticles

In the last decades ethanol and glycerol arose as potential fuels for fuel cells. Based on their importance to the field and molecular similarity, here we compare the electrooxidation of ethanol and glycerol on platinum nanoparticles as an attempt to learn about their differences and similarities in terms of oxidation pathways. By using in situ FTIR we interpret the electrochemical behavior in terms of different pathways involving the production of carboxylic acids for both alcohols. For ethanol, CO2 is produced from CO in a direct pathway involving several electrons, while acetic acid is produced through a parallel pathway. Conversely, for glycerol CO2 seems to be mainly produced through a sequential pathway involving carboxylic acids, each one involving few electrons. The results suggest that glycerol demands surfaces that speed up the oxidation of partially oxidized species formed at intermediate potentials.