The oscillatory electro-oxidation of formic acid: Insights on the adsorbates involved from time-resolved ATR-SEIRAS and UV reflectance experiments

Galvanostatic potential oscillations during the oxidation of formic acid were studied by time-resolved Surface Enhanced Infrared Absorption Spectroscopy in the attenuated total reflection configuration (ATR-SEIRAS) and reflectance measurements in the ultraviolet (UV) region. ATR-SEIRAS allowed monitoring oscillations in the coverage of adsorbed CO (COad) and adsorbed bridge-bonded formate (HCOObi), while UV reflectance revealed oscillations in the coverage by specifically adsorbed anions (namely, adsorbed sulfate). The potential oscillations and the coverage of all these species are strongly interconnected, and an analysis of their correlation provides detailed insight into the autocatalytic loop responsible for the emergence of non-linear dynamics. (AU)