INVESTIGATION OF THE EARLY STAGES OF H-ADS AND OHADS ADSORPTION ON RHODIUM IN ALKALINE-MEDIUM .1. APPROACHES FROM GRAPHICAL TREATMENTS OF CYCLIC VOLTAMMOGRAMS BASED ON A LANGMUIRIAN ISOTHERM

Using a simple model of adsorption based on a Langmuir isotherm allows us to determine the elementary step involved in the adsorption and desorption of small species such as H-ads, OHads on noble metals in aqueous medium. This first part, concerning a rhodium electrode, shows an example of the treatment of I-E curves in cyclic voltammetry by using graphical or numerical deconvolution. Normalized parametric equations are presented to model the I-E curve shapes corresponding to the two limiting cases of electron transfer reactions (reversible and irreversible reactions). This technique may help in writing adsorption mechanisms by exploiting the numerical characteristics of the deconvoluted peaks. The comparison of the charge associated with a deconvoluted peak and of a theoretical charge allows us to assign a given structure for the adsorbed species.