Adsorption of complex silver cyanides on Ag(111). Quantum chemical consideration

Resumo

The interaction of AgCN molecules and Ag(CN)₂⁻, Ag(CN)₃²⁻, Ag(CN)₄³⁻ ions with the silver surface is studied based on the cluster model of the metal surface by quantum chemistry methods. The geometrical and energy parameters of the interaction of these species with the metal surface are assessed. As regards the strength of their chemical bond with the surface, these compounds form the following series: Ag(CN)₂⁻ < Ag(CN)₃²⁻ < AgCN < Ag(CN)₄³⁻. The surface activity of silver-containing species is compared with regard to the solvent effect. It is found that Ag(CN)₂⁻ and Ag(CN)₃²⁻ anions exhibit close adsorbabilities on silver. Molecules AgCN are not accumulated on the surface because of their very low content in solution. The adsorption of Ag(CN)₄³⁻ is hindered due to a considerable value of degradation energy of this three-charged ion. In the adsorbed state, the ions Ag(CN)₂⁻ and Ag(CN)₃²⁻ represent stable compounds displaying no surface dissociation to yield compounds with the smaller coordination numbers.