Adsorption of 1-heptanol on bismuth single-crystal plane electrodes

Cyclic voltammetry, impedance and chronocoulometry have been employed for the quantitative study of 1-heptanol (1-HepOH) adsorption on the bismuth single-crystal plane|aqueous Na₂SO₄ solution interface. The adsorption isotherms, Gibbs energies of adsorption, , the limiting surface excess, Γ_max, and other adsorption parameters have been determined. The adsorption of 1-HepOH on Bi single-crystal planes is mainly physical and is limited by the rate of diffusion of organic molecules to the electrode surface. Comparison of the adsorption data for 1-HepOH with other alcohols shows that the adsorption characteristics depend on the structure of the hydrocarbon chain. The adsorption activity of adsorbates at the bismuth|solution interface increases in the sequence 1-propanol<1-butanol<1-pentanol<1-hexanol<1-heptanol as the adsorption activity at the air|solution interface increases. For all the compounds studied, the adsorption activity increases in the sequence of planes as .