Abstract:

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 Dmol3 implementation of the conductor like solvent model (COSMO), to investigate CO and H2 adsorption on Cu(111) surface in vacuumand 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 Dmol3, CO and H2 adsorption on Cu(111) surface are both nondissociative adsorption when the Cu surface is adsorbed by CO and H2 in vacuum or liquid paraffin except H2 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. H2 can be not parallel adsorption on Cu(111) surface in vacuum, but it is nearly vertical or vertical adsorption. When H2 is vertical adsorption on Cu(111) surface at top site, solvent effects can improve the stability of H2 adsorption on Cu(111) surface, there is no influence on H2 activation. When H2 is vertical adsorption on Cu(111) surface at bridge, fcc and hcp sites in liquid paraffin, the stability of H2 adsorption on the Cu(111) surface decreases compared with H2 adsorption in vacuum, however, the extent of H2 activation increases. As H2 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 fcc site, and another H atomis at hcp site.

Key words: Density functional theory, CO molecule, H2 molecule, Cu(111) surface, Solvent effect, Adsorption