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Slow Formation of an Extra‐Viscous Ionic Layer at Platinum Microelectrodes During Voltammetric Oxidation of Undiluted Dimethylformamide
Author(s) -
Gadomska Joanna,
Stojek Zbigniew
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(199804)10:5<307::aid-elan307>3.0.co;2-v
Subject(s) - chronoamperometry , chemistry , microelectrode , voltammetry , cyclic voltammetry , propylene carbonate , platinum , dimethylformamide , inorganic chemistry , analytical chemistry (journal) , diffusion , steady state (chemistry) , electrochemistry , electrode , solvent , chromatography , organic chemistry , catalysis , thermodynamics , physics
Abstract A minimum appears on the steady‐state anodic voltammetric waves of undiluted dimethylformamide (DMF) and its concentrated solutions in acetone and propylene carbonate. The magnitude of the minimum obtained in undiluted DMF depends strongly on the experimental time scale and was examined using chronoamperometry and normal pulse‐ and reverse pulse voltammetry. The rate of formation of the minimum is much lower compared to that of reaching the steady state. The experiments done and the fact that the minimum vanishes at the potential where water is oxidized favor a concept that the ionic product in the ionic liquid at the surface of the Pt microelectrode is being hydrated and this leads to extra viscosity of the layer. The process is slow, since the rate of hydration is determined by diffusion of traces of water from the bulk. The products of oxidation of DMF are rather soluble, as found by long‐range reverse pulse voltammetry. This technique is apparently also useful for the estimation, in situ, of the water content in DMF.