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

Cyclic reciprocal derivative chronopotentiometry (CRDC) is applied to the c haracterisation 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 deriv ative of the analytical equations corresponding to the chronopotentiograms (potential time curves) deduced in a previous paper in cyclic chronopotenti ometry. The expressions corresponding to the simpler case of strong adsorpt ion of both species have been deduced as a limit case of these general equa tions. When two successive cathodic and anodic currents tone cycle) are applied, t he dt/dE-E response presents two peaks whose ratio of the heights and diffe rence between their potentials afford simple diagnosis criteria to characte rise different adsorption processes. Moreover, these processes can be furth er confirmed through the use of more than one current cycle. Methods for de termining adsorption parameters are also proposed. (C) 1999 Elsevier Scienc e Ltd. All rights reserved.