Cyclic reciprocal derivative chronopotentiometry.: Applications to the detection and characterisation of adsorption processes

Cyclic reciprocal derivative chronopotentiometry (CRDC) is applied to the characterisation of different electrode processes in which the adsorption of the reactant and/or the product takes place. The dt/dE-E curves have been obtained by making the analytical or numerical reciprocal of the time derivative of the analytical equations corresponding to the chronopotentiograms (potential time curves) deduced in a previous paper in cyclic chronopotentiometry. The expressions corresponding to the simpler case of strong adsorption of both species have been deduced as a limit case of these general equations. When two successive cathodic and anodic currents tone cycle) are applied, the dt/dE-E response presents two peaks whose ratio of the heights and difference between their potentials afford simple diagnosis criteria to characterise different adsorption processes. Moreover, these processes can be further confirmed through the use of more than one current cycle. Methods for determining adsorption parameters are also proposed. (C) 1999 Elsevier Science Ltd. All rights reserved.