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Faradaic Reactions at Glassy Carbon Surfaces Studied by Coulometric Stripping Potentiometry
Author(s) -
Sahlin Eskil,
Jagner Daniel
Publication year - 1998
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/(sici)1521-4109(199805)10:6<374::aid-elan374>3.0.co;2-b
Subject(s) - coulometry , electrolysis , glassy carbon , chemistry , stripping (fiber) , inorganic chemistry , cathodic stripping voltammetry , analytical chemistry (journal) , metal , oxygen , bulk electrolysis , faraday efficiency , carbon fibers , electrochemistry , voltammetry , cyclic voltammetry , electrode , chromatography , materials science , organic chemistry , composite material , composite number , electrolyte
Coulometric stripping potentiometry has been used for the quantitative determination of Faradaic reactions on glassy carbon surfaces. Exhaustive cathodic electrolysis in samples (10 μL) containing known amounts of Bi III , Cu II , Pb II or Cd II , subsequent stripping of the amalgamated atoms with a constant oxidative current, and evaluation of the amount of metal ions, using Faraday's law, frequently yielded too high values. For example, when electrolyzing a sample containing 100 μM of Cu II at −1.60 V a value of 109 μM was obtained, the corresponding value at an electrolysis potential of −0.90 V being 101 μM. The discrepancies were attributed to re‐oxidation of electroactive surface groups, reduced during cathodic electrolysis, simultaneous with the oxidation of the amalgamated elements. As expected, it was found that this interference was more pronounced the more cathodic the electrolysis potential. The kinetics of the re‐oxidation was studied revealing half times in the order of 0.4 to 0.6 ms. An oxygen to carbon surface atomic ratio equal to 0.08 was found assuming that all electroactive groups contained oxygen and one electron per oxygen atom was involved in the oxidation.