Quarterly of Applied Mathematics

Quarterly of Applied Mathematics

Online ISSN 1552-4485; Print ISSN 0033-569X



ECE versus DISP electrochemical competition

Authors: S. L. Cole and J. W. Wilder
Journal: Quart. Appl. Math. 47 (1989), 459-486
MSC: Primary 92A40; Secondary 80A32
DOI: https://doi.org/10.1090/qam/1012270
MathSciNet review: MR1012270
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Abstract: The ECE (Electrochemical, Chemical, Electrochemical) and DISP (DISProportionation) mechanisms describe electrochemical reactions between four species in a diffusive solution. The general set of reactions which encompass both mechanisms is modelled by:

$\displaystyle A + {e^ - } \to B$

        (at the electrode)         (i)

$\displaystyle B \rightleftharpoons C$

        (throughout the solution)         (ii)

$\displaystyle C + {e^ - } \to D$

        (at the electrode)         (iii)

$\displaystyle B + C \rightleftharpoons A + D$

        (throughout the solution)         (iv) in the case when the applied overpotential is large enough that only the forward steps in (i) and (iii) are present. The ECE mechanism follows the pathway (i), (ii), (iii). The DISP mechanism follows the pathway (i), (ii), (iv). These electrochemical mechanisms play an important role in many organic reactions such as cleavage processes and in inorganic reactions such as the production of forms of technicium used as a radiopharmaceutical. It is important to understand these mechanisms in order to better predict product synthesis and performance. This paper uses asymptotic expansion and perturbation techniques to provide rigorous, relatively simple analytic/numerical solutions for the (linear) ECE mechanism, the (weakly nonlinear) DISP mechanism and a (weakly nonlinear) ``competition'' mechanism involving all four pathway steps. It is shown that for large dimensionless time, the ECE mechanism evolves to a state with only two species present in order one quantities. Yet, the DISP mechanism retains all four species in order one amounts when step (iv) is reversible. The competition mechanism behaves like the ECE mechanism for small time yet evolves for large time to a form more similar to the DISP mechanism showing that nonlinear effects eventually dominate the mechanistic behavior.

References [Enhancements On Off] (What's this?)

  • [1] G. S. Alberts and I. Shain, Electrochemical study of kinetics of a chemical reaction coupled between two charge transfer reactions, J. Anal. Chem. 35, 1859-1866 (1963)
  • [2] C. Amatore and J. M. Saveant, ECE and disproportionation, part V. Stationary state general solution application to linear sweep voltammetry, J. Electroanal. Chem. 85, 27-46 (1977)
  • [3] C. Amatore and J. M. Saveant, ECE and disproportionation, part VI. General resolution. Application to potential step chronoamperometry, J. Electroanal. Chem. 102, 21-40 (1979)
  • [4] S. W. Feldberg, Nuances of the ECE mechanism. III. Effects of homogeneous redox equilibrium in cyclic voltammetry, J. Phys. Chem. 75, 2377-2380 (1971)
  • [5] S. W. Feldberg and L. Jeftic, Nuances of the ECE mechanism. IV. Theory of cyclic voltammetry and chronoamperometry and the electrochemical reduction of hexacyanochromate (III), J. Phys. Chem. 76, 2439-2446 (1972)
  • [6] J. Galvez and A. Molina, Pulse polarography, part V. On the theory for the kinetic currents with an ECE mechanism, J. Electroanal. Chem. 107, 87-94 (1980)
  • [7] M. D. Hawley and S. W. Feldberg, Nuances of the ECE mechanism. I. Development of the theoretical relationships for chronoamperometry, J. Phys. Chem. 70, 3459-3464 (1966)
  • [8] L. S. Marcoux, R. N. Adams, and S. W. Feldberg, Dimerization of triphenylamine cation radicals. Evaluation of kinetics using the rotating disk electrode, J. Phys. Chem. 73, 2611-2614 (1969)
  • [9] R. S. Nicholson and I. Shain, Theory of stationary electrode polarography for a chemical reaction coupled between two charge transfers, J. Anal. Chem. 37, 178-190 (1965)
  • [10] J. M. Saveant, C. P. Andrieux, and L. Nadjo, Disproportionation and ECE mechanisms, J. Electroanal. Chem. 41, 137-141 (1973)
  • [11] J. W. Wilder, Analytic solutions for electrochemical mechanisms involving coupled homogeneous and heterogeneous chemistry, Ph.D. Dissertation, Rensselaer Polytechnic Institute, Troy, NY, (1988)

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DOI: https://doi.org/10.1090/qam/1012270
Article copyright: © Copyright 1989 American Mathematical Society

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