P. Nikitas, GENERALIZED EXPRESSIONS FOR CHEMICAL-POTENTIALS AND ADSORPTION-ISOTHERMS OF NEUTRAL ORGANIC-COMPOUNDS ON ELECTRODE SURFACES, Electrochimica acta, 39(7), 1994, pp. 865-871
Generalized expressions for the chemical potentials of the constituent
s of films absorbed on ideally polarized electrode surfaces and compos
ed of neutral organic absorbates are derived within the frames of clas
sical thermodynamics and the electrostatic theory of the dielectrics.
The chemical potentials are used for the derivation of adsorption isot
herms, the properties of which are compared with experiment. This comp
arison reveals that the dipoles of the adsorbed species do not reorien
tate continuously, but they have either a constant or certain distinct
orientations with respect to the electrode surface. In this case, the
isotherms are in general congruent with respect to the potential drop
across the adsorbed film. Deviations from the congruence may reflect
either the existence of more than one solvent state simultaneously at
the adsorbed layer or changes in the thickness of this layer during th
e adsorption process. The analysis of the adsorbed layer properties ha
s not led to conditions which favour the appearance of congruence with
respect to the electrode charge density.