Adsorption Effects of Highly Polarizable Organic Compounds on Electrode Kinetics

Abstract

Adsorption effects of ureas and thioureas on electrode kinetics were studied by using the electrode reactions of Zn2+/Zn(Hg) and Eu3+/Eu2+. The standard rate constant for Zn2+/Zn(Hg) is controlled by the inner-layer permittivity. The effect of this permittivity has been explained in terms of the solvent reorganization energy. The effect of the adsorbates on the electrode kinetics of Eu3+/Eu2+ cannot be explained in terms of the inner-layer permittivity. These two results suggest different locations for the formation of the activated complex: Inside the adsorption layer for Zn2+ and just outside layer for Eu3+.

The Catalytic Impact of Ethionine on the Multi-Step Electroreduction of Bi(III) Ions in Chlorates(VII) Solutions

“…Studies on the kinetics of various depolarisers in the presence of electrode substances are comprehensively discussed in the literature [5][6][7][8][9][10][11]. It was demonstrated that the structures of the inter-phase area caused by adsorption of organic compounds on the surface of mercury play a significant role in the mechanism of the cap-pair effect.…”

Kinetics and Mechanism of Zn(II) Ions Electroreduction Catalyzed by Organic Compounds

“…Ikeda [12] studied the problem of electroreduction acceleration by organic substances. Ikeda associated the constant reduction rate of depolarizer k s with the electrical permittivity e. For Zn(II) ions electroreduction in the presence of thiourea and its derivatives the dependence ln k s ¼ f(1/e) is linear.…”

Influence of Thiourea on the Activation Energy of the Electroreduction Process of Zn(II) in Mixed Solvents on the Mercury Electrode

“…As suggested by Ikeda et al [16], the lack of changes in this potential does not exclude the possibility of the formation of complexes on the electrode surface.…”