Chronoamperometric resolution of ion and solvent transfers at a poly( o-toluidine) modified electrode by combined electrochemical quartz crystal microbalance (EQCM) and probe beam deflection (PBD)

• Published in: Electrochimica acta 2000-07, Vol.45 (22), p.3885-3894
• Main Authors: Henderson, Mark J., Hillman, A.Robert, Vieil, Eric
• Format: Article
• Language: English
• Subjects: Chronoamperometry; Convolution; Electrochemical quartz crystal microbalance (EQCM); Poly( o-toluidine); Probe beam deflection (PBD)
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/S0013-4686(00)00453-9

Combined electrochemical quartz crystal microbalance (EQCM) and probe beam deflection (PBD) measurements on short time scales following the application of a potential step are presented. The procedure for evaluating the exchange of mobile species (ions and solvent) is illustrated by application of the combined technique to a poly( o-toluidine) (POT) film redox switching in aqueous HClO 4 solutions. A comparison of the predicted PBD profiles calculated from the current and mass responses to that of the measured PBD signal, by temporal convolution analysis, enabled the contributions of anion (ClO 4 −) and solvent (H 2O) transfer at the first redox step to be discriminated quantitatively. The results are consistent with a mechanism where anion exchange involves a counter flux of solvent, and suggest that a film volume constraint is applicable on the time scale of the experiment. During oxidation and reduction, the EQCM indicates a non-equilibrium movement of anions, confirmed by convolution analysis of the associated current and deflection signals.