We use density functional theory (DFT) combined with conductor-like solvent model (COSMO) to study different solvent mother solution-copper interfacial properties, which are believed to play a key role in the "one-pot" synthesis of dimethyl ether (DME) from syngas in a slurry reactor. For three relevant crystallographic planes - (1 1 1), (1 1 0), and (1 0 0) - we develop a theoretical approach for calculating surface energies which cannot be determined experimentally. The surface energies show that the solvent not only has a strong effect on copper morphology, but also affects the Mulliken charges of Cu(h k I) surfaces. We also study CO molecules adsorbing on Cu(h k I) surfaces. It is found that both the structural parameters and the relative energies of CO are very sensitive to the COSMO solvent model. Thus the solvent effects can improve the stability of CO adsorption on Cu(h k I) surface and the ability of CO activation. This analysis gives us some new insights into the understanding of solvent effects. (C) 2010 Elsevier B.V. All rights reserved.