Electrooxidation of glycerol on platinum nanoparticles: Deciphering how the position of each carbon affects the oxidation pathways

•Glycerol forms CO and CO2 from both terminal (13CH2OH) and central (12CHOH) groups.•The oxidation of the terminal group is easier than that of the central group.•The formation of 13CO2 seems to be favored through a L-H mechanism.•Glyceraldehyde seems to intermediate the formation of glyceric acid. In this work we investigate the electrooxidation of glycerol on platinum nanoparticles in acidic media. By using in situ FTIR and isotopically labeled glycerol (13CH2OH12CHOH13CH2OH) we follow the reaction during a full cycle of oxidation and unravel the role of some important species on the electrooxidation pathways. Results indicate that terminal (13CH2OH) and central (12CHOH) groups are able to form adsorbed CO and that both contribute to the production of CO2, although the terminal groups are easier to be oxidized than the central one, probably due to the steric effect provoked by 13CH2OH which prevents the oxidation of 12CHOH. Moreover, glyceraldehyde seems to be an important intermediate for the generation of glyceric acid.