Dissociation of carbon monoxide on rhodium surfaces

Abstract

The dissocn. of CO on the (111), stepped (111), (100), and (110) surfaces of Rh was studied with the atom superposition and electron delocalization (ASED) MO method. For each surface several possible reaction paths are proposed, which the activation energy is calcd. Reaction paths with the lowest activation energy have in common that in the 1st stage the O atom bends to the metal surface, while in the 2nd stage the O atom is moving away from the C over a surface Rh atom. This results in a transition state where both C and O atoms are bonded to this surface Rh atom. Calcns. of the local d. of states of CO show considerable occupation of the 2p* orbital of CO in the transition state. Large metal ensembles are necessary for CO dissocn., since after dissocn. C and O are adsorbed on sites sharing a min. no. of surface metal atom