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Published July 1, 2011 | public
Journal Article

Large-amplitude ac voltammetry: Theory for reversible redox reactions in the "slow scan limit approximation"

Abstract

Analytical solutions for the current response of an ac voltammetric experiment on a reversible redox system have traditionally relied on two approximations: the "slow scan limit approximation" and small ac potential amplitudes. There has been no rigorous analytical investigation of the limits of validity of the solutions derived under the first assumption, and the second assumption only allows for small currents, which restricts the applicability of the method. In this article, we derive a novel analytical solution for the current response, valid for ac potential excitations of any magnitude. We establish rigorous estimates of the error induced by the slow scan limit approximation and discuss in detail how this should influence the choice of experimental parameters. The effects of double-layer capacitance are generally large under the slow scan limit approximation and can cause difficulties in isolating the higher harmonics due to spectral leakage in the power spectrum of the FFT. We demonstrate how the Hann window can be used to overcome this problem in the case of linear capacitance. Finally we show how parameters describing the electrochemical system (including linear capacitance) can be deduced from features of the time-dependent harmonic envelopes and the dc part of the current response, without the need for baseline subtraction.

Additional Information

© 2011 Elsevier Ltd. Received 19 January 2011; revised 15 April 2011; accepted 16 April 2011. Available online 27 April 2011. The authors gratefully acknowledge funding for this project provided by the Engineering and Physical Sciences Research Council (EPSRC) (grant number EP/F044690/1).

Additional details

Created:
August 22, 2023
Modified:
October 23, 2023