l-Cysteine oxidation studied by rotating ring disk electrodes: Verification of reaction intermediates

Mechanism of Electrochemical L‐Cysteine Oxidation on Pt

“…The potential region of the second shoulder is close to the potential of PtO formation, which is considered the oxidative species for this reaction. We assign the shoulder to the generation of adsorbed sulfone since it is close to the potential of the ν‐SO 2 related band at 0.90 V. This adsorbed intermediate was already suggested by IRRAS and rotating ring‐disk electrode studies . The peak observed at approximately 0.90 V for the Abs’/E profile is in agreement with the previous publication that presented an I ring /E profile that was interpreted as being limited by the adsorbed sulfone generation …”

“…The oxidative species most likely is PtOH based on the potential region in which the shoulders are observed. The product of this oxidation is probably a desorbed intermediate as suggested previously ,. These desorbed species could not be detected by the internal reflection set up since this is not the best set up for solution analysis.…”

“…Electrochemical measurements indicated a mechanism involving chemical steps,, and all the suggested species were observed by IRRAS . However, some assumptions in the literature are still not clear, such as the suggestion that oxygen transport to the oxidized species arises from the formation of a metal oxide .…”

“…A recent review presents all this controversy and recent efforts for a better understanding of this process. Several studies have found that some other intermediates formed in steps with transfer of fewer electrons.…”

“…However, some assumptions in the literature are still not clear, such as the suggestion that oxygen transport to the oxidized species arises from the formation of a metal oxide . This is controversial if one considers some recently proposed chemical steps ,. Additionally, the dependence on the pH of the observed Kolbe decarboxylation is still not fully understood.…”