Adsorption of D-ribose on bismuth single crystal plane electrodes

Abstract

Cyclic voltammetry and impedance have been employed for the quantitative study of D-ribose adsorption on the bismuth single crystal planes | 0.05 M Na 2SO 4 aqueous solution interface. The adsorption of D-ribose on Bi planes is mainly limited by the diffusion step and thus the D-ribose adsorption in the region of zero charge potential E σ=0 is physical. The adsorption isotherms, Gibbs energy of adsorption, the maximal surface excess Γ max and other adsorption parameters have been determined. The limiting Gibbs adsorption Γ max of D-ribose decrease in the sequence of Bi planes (001)>(111)>(011̄) as the reticular density of planes increases in the sequence (001)<(111)<(011̄). The very low values of Γ max and the limiting potential shift of zero charge, caused by the replacement of water monolayer by the monolayer of D-ribose, indicate that the D-ribose molecules probably have a flat orientation at Bi surface. The molecular interaction parameter a in the Frumkin isotherm decreases in the sequence of planes (111)>(001)>(011̄). The negative values for Bi(001) and Bi(011̄) planes indicate that there is a repulsive interaction between the adsorbed D-ribose molecules.