Oscillatory electro-oxidation of ethanol on platinum studied by in situ ATR-SEIRAS

We report the study of the oscillatory electro-oxidation of ethanol on platinum surfaces under galvanostatic conditions. In order to correlate the features of potential oscillations with the surface chemistry of different adsorbates, we use in situ surface-enhanced infrared absorption spectroscopy in the attenuated total reflectance mode (ATR-SEIRAS). Results show that the maintenance of the oscillatory state does not seem to be particularly correlated with the CO surface coverage, conversely to what is observed for methanol. Indeed, our data suggest that oscillations continue as long as the coverage of molecular fragments from ethanol (regardless its nature) remain within a range that allows the coexistence of surface oxides (responsible for the activation of the surface throughout oxidation steps). Our results throw some light in the oscillatory kinetics of ethanol by establishing an unequivocal correlation between the features of the galvanostatic oscillations and the dynamics of the adsorbed species.