Comparative study of the interaction of CO and CO2 with Ni-2 cluster

The interaction of CO and CO2 with nickel has been studied comparatively us ing the ab initio method. The results show that the carbon-oxygen bond is w eakened when CO interacts with nickel, and the weakening is more obvious in the bridged adsorbed model than that in the linear one. The calculated vib rational frequencies are close to those found experimentally. Three interac tion modes of CO2 with a Ni-2 small cluster are found to be possible in whi ch the most stable one has a bidentate structure, i.e. two oxygen atoms bon ded to two adjacent nickel atoms, respectively. The weakening of the carbon -oxygen bond is more remarkable in the CO2 adsorbed model than in the CO ad sorbed one. The Ni-2 cluster structure suitable for CO2 is different from t hat for CO except that the Ni-Ni interatom distance in the CO bridged adsor bed species is significantly close to that in CO2 bidentate species. (C) 19 99 Elsevier Science B.V. All rights reserved.