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.
Bibliographical noteThe support of the University of Aberdeen is gratefully acknowledged. F.W.H. and H.V. acknowledge São Paulo Research Foundation (FAPESP) for the scholarship (grant #2014/08030-9, grant #2017/07286-8) and financial support (grant #2013/16930-7). HV (grant #306151/2010-3) acknowledges Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for financial support. This study was also supported by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001.
- formic acid oxidation
- potential oscillations
- pH effect
- differential reflectance spectroscopy