Carbon-monoxide adsorption and dissociation on Nb(1Â 1Â 0) surface

The adsorption of CO on the Nb(1 1 0) surface has been studied by using the density-functional theory with total-energy calculations. In addition to the adsorption geometries, the vibrational properties, surface electronic structures, and dissociation pathways of CO adsorption on the Nb(1 1 0) surface have been investigated. The Perdew-Burke-Ernzerhof (PBE), meta generalized gradient approximation (meta-GGA), and hybrid functional (HSE06) functionals were applied to discuss the site preference in the Nb-p(1 × 1) surface. Results showed that the inclined CO adsorbed on the hollow sites is the most stable structure from total-energies using different functionals. Furthermore, at lower coverage, CO molecules adsorbed on the Nb(1 1 0)-p(2 × 2) surface are easy to dissociate to forming the atomic adsorption from NBE calculations. PDOS showed that in the cases of CO adsorbed on hollow and bridge sites, the σ orbitals of CO molecule hybridize with d orbitals of Nb atom apparently, while on top sites, the 2π* orbitals of CO molecule interact with Nb d orbitals intensely.