Kinetics of chloride ion adsorption and the mechanism of AgCl layer formation on the (111), (100) and (110) faces of silver

The kinetics of chloride anion adsorption on the (111), (100) and (110) faces of silver are investigated by linear sweep voltammetry, potentiostatic pulse and impedance (admittance) measurements. It is shown that the first voltammetric (capacitive) peak corresponds to the adsorption of randomly arranged chloride anions with complete charge transfer between the anions and the substrate (l approximate to 1) and a relatively slow rate of adsorption: k(s) = (8-9) x 10(-6) cm s(-1). The second (third) voltammetric (capacitive) peak is found to be very sharp, representing (according to the earlier findings) the formation of an ordered AgCl adlayer formed with the topmost Ag layer. At more positive potentials a three-dimensional (3D) growth of AgCl takes place, characterized by the anodic ''crystallization loop'' and the j-t transients typical of 3D nucleation. It is shown that after prolonged polarization in the potential region of 3D AgCl formation, irreversible formation of AgCl takes place on the electrode surface.