Interaction of carbon monoxide with Rh (112) metal surface

Abstract

A semiempirical topological method was employed in a study of Rh (112) surface as well as dissociative and nondissociative chemisorption of carbon monoxide on this surface. A basic structural unit was used which consisted of 27 metal atoms. The terminal atoms were coiled into a torus in order to achieve a conservation of the translational symmetry corresponding to the infinite crystal. Calculations have revealed that the positive charge is concentrated entirely near the Rh crystal surface, which is considered to be in accord with the small reactivity of the Rh surface. The dissociative chemisorption of carbon monoxide on the Rh(112) surface is energetically prohibited. The linear adsorption of carbon monoxide can occur on Rh surface sites preferentially on the top positions. In all cases studied, the attachment of carbon to the surface is energetically more favourable than the attachment of oxygen. The orientation of CO molecule perpendicular to the terrace is more favourable than that perpendicular to the step in all captures under study. In all systems a charge transfer is observed from the metal to the CO molecules. Such a transfer makes the CO molecule similar to alcoholate and enhanced reactivity toward electrophilic agents can be anticipated in this case.