Abstract: Clean and oxygen-modified Cu(100) surfaces have been used to model the metallicand the partially oxidized copper surfaces respectively.Activati0n energies for elementary re-actions involved in the methanol synthesis from CO₂/H₂ over Cu (100) and Cu (1O0)-p(2×2)Osurfaces have been calculated using bond order conservation-Morse potential approach.The following conclusions have been obtained: the main pathway for methanol formation canbe expressed as "CO_2,s→HCOO₃→H₂CO₃→CH₃O₃→CH₃OH_s"; In comparison withthat over the clean Cu(100) surface, each elementary reaction involved in methanol synthesishas a lower activation energy over the oxygen-modified Cu(100) surface;HCOO_s is the com-mon precursor intermediate for methanol and COformations and the selectivity of methanolis governed by the relative reaction rate of hydrogenolysis of formate to the dissociation offormate (to CO_s+ OH_s); Over the clean Cu(100) surface, the activation energy for formatehydrogenolysis is similar to that for formate dissociation to CO_s and OH_s, while the former ismuch lower than the latter over the oxygen-modified Cu (100) surface- Judging by the activa-tion energies, we conclude that methanol synthesis from CO₂/H₂ is more favorable over thepartially oxidized copper surface than that over the metallic copper surface.

Key words: Copper surface, Hydrogenation of CO₂, Methanol synthesis, Reaction energet-ics, Bond order conservation approach