Mechanism of Electrochemical L‐Cysteine Oxidation on Pt

Abstract The electrochemical behavior of L‐cysteine on Pt electrodes was studied by in situ attenuated total reflection Fourier transform infrared spectroscopy (ATR‐FTIRS) and online differential electrochemical mass spectrometry (DEMS). The ATR‐FTIRS measurements allowed verification of the electrochemical mechanism of the oxidation of this molecule. The time resolution of the technique was crucial for relating each functional group to the faradaic current, suggesting electrochemical and chemical steps for the S atom oxidation. The DEMS experiments do not allow verification of desorbed intermediates due to their high solvation. Nevertheless, this technique was crucial for detecting side reactions, such as the decarboxylation of the adsorbed intermediates observed mainly under highly acidic conditions, in contrast to the conventional Kolbe mechanism.