A comparative study of CO chemisorption on flat and stepped Ni surfaces using density functional theory

Comparative studies of CO adsorption on Ni (1 1 0), Ni(1 1 1), Ni(2 1 0), and Ni(5 3 1) surfaces are carried out with density functional theory. On each surface, the favored adsorption site is determined by considering multiple possible adsorption sites. Adsorption energies and structural properties are compared with experimental results on the (1 1 0) and (1 1 1) surfaces. In both cases, good agreement with experimental data is found. At surface coverages where adsorbate–adsorbate interactions are relatively weak, the adsorption energy of CO is very similar on the four Ni surfaces. We show that CO bonding on each of these four Ni surfaces is quite similar, with the main contributions arising from the 5σ and the 2π molecular orbitals of CO. The implications of our results for understanding the structure sensitivity of CO dissociation on Ni are discussed.