Adsorption and dissociation of CO on body centered cubic transition metals and alloys : effect of coverage and scaling relations

The adsorption and dissociation of CO has been calculated on the surface plane of the body centered cubic (BCC) transition-metals Fe, Mo, Cr, and W using density functional theory (DFT) for two CO coverages; 0.25 and 0.5 ML. The coverage effect will be discussed for the adsorption energy, tilting angle, and stretch frequency of CO. Furthermore, the effect of coverage will be presented by means of complete energy diagrams of the dissociation reaction of tilted CO on all four metals. Lastly, we will show that scaling relations apply to a bent CO species on all four transition metals as well as the metal-alloys Fe3Mo and Fe3Cr, in the sense that heat of adsorption of CO and the activation energy of CO dissociation scale linearly with the heat of adsorption of the carbon.