Adsorption of pyridine at the Au( 110)-solution interface

The energetics of pyridine adsorption onto a Au(110) surface have been characterized quantitatively using chronocoulometry. The adsorption parameters such as relative Gibbs surface excesses, Gibbs energies of adsorption, and electrosorption valencies have been determined as a function of the electrode potential and the surface-charge density. The maximum surface excess is equal to 6.1 × 10−10 mol cm−2, the Gibbs energy at the potential of maximum adsorption is −42 kJ mol−1, and the shift of the potential of zero charge (pzc) due to displacement of a monolayer of water molecules by a monolayer of adsorbed pyridine is −0.65 V. It is concluded that pyridine molecules are adsorbed vertically on a Au(110) surface, attached to the metal by the nonbonding orbital of the nitrogen atom. Adsorption of pyridine at Au(110) and Au(100) surfaces are compared. The strong effect of surface crystallography on the energetics of pyridine adsorption at gold electrodes is shown.

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