CO and H2 Molecules Adsorption on Cu(111) Surface and Solvent Effects

The calculations were performed by using density functional theory (DFT), where the generalized gradient approximation (GGA) corrected exchange-correlation functional proposed by Perdew and Wang (PW91) was chosen together with the doubled numerical basis set plus polarization basis sets (DNP), using the Dmol(3) implementation of the conductor like solvent model (COSMO), to investigate CO and H-2 adsorption on Cu(111) surface in vacuum and liquid paraffin. It is found that both structural parameters and relative energies are very sensitive to the COSMO solvent model. According to the monitor bonding function of the Dmol(3), CO and H-2 adsorption on Cu(111) surface are both nondissociative adsorption when the Cu surface is adsorbed by CO and H-2 in vacuum or liquid paraffin except H-2 parallel adsorption in liquid paraffin which is dissociative adsorption. The results show that solvent effects can improve the stability of CO adsorption on Cu (111) surface and the extent of CO activation in liquid paraffin. H, can be not parallel adsorption on Cu(111) surface in vacuum, but it is nearly vertical or vertical adsorption. When H-2 is vertical adsorption on Cu(111) surface at top site, solvent effects can improve the stability of H-2 adsorption on Cu(111) surface, there is no influence on H-2 activation. When H-2 is vertical adsorption on Cu(111) surface at bridge, fcc and hcp sites in liquid paraffin, the stability of H-2 adsorption on the Cu(111) surface decreases compared with H-2 adsorption in vacuum, however, the extent of H-2 activation increases. As H-2 is parallel adsorption on Cu(111) surface in liquid paraffin, H-H bond is broken by solvent effects. One H atom adsorbs on Cu(111) at fee site, and another H atom is at hcp site.