The effect of diffuse layer on adsorption potential shifts and differential capacitance in systems (In-Ga)/[N-methylformamide + mc KA + (1 - m)c KClO4], where KA is KCl, KBr and KI

Abstract

By the regression analysis of dependences of the adsorption potential shift (Eads) on the electrode charge in systems (In-Ga)/[NMF + 0.1m M KCl + 0.1(1 - m) M KClO4, (In-Ga)/[NMF + 0.1m M KBr + 0.1(1 − m) M KClO4], and (In-Ga)/[NMF + 0.1m M KI + 0.1(1 - m) M KClO4] with the following m fractions of the surface-active anion: 0.05, 0.1, 0.2, 0.5, and 1, the adsorption parameters are calculated in terms of two models both based on the Frumkin isotherm and considering the free adsorption energy as a function of the electrode charge, where one model takes into account the diffuse layer and the other ignores it. It is shown that for the studied electrode charges q ≤ 10 μC/cm2, both models provide equal accuracy in calculating Eads and the differential capacitance (C) in the systems under study. However, for determination of adsorption parameters, the regression analysis of Eads vs. q curves has several advantages over the analogous analysis of C vs. q curves.