Adsorption of 2-chlorophenol on Cu ₂ O(1 1 1)-Cu _CUS: A first-principles density functional study

First-principles density functional theory and a periodic-slab model have been utilized to investigate the adsorption of a 2-chlorophenol molecule on a CuO(1 1 1) surface with a vacant Cu surface site, namely Cu ₂ O(1 1 1)-Cu _CUS . Several vertical and flat orientations have been studied. All of these molecular configurations interact very weakly with the Cu ₂ O(1 1 1)-Cu _CUS surface, an observation which also holds for clean copper surfaces and the Cu ₂ O(1 1 0):CuO surface. Hydroxyl-bond dissociation assisted by the surface was found to be endoergic by 0.42-1.72 eV, depending predominantly on the position of the isolated H on the surface. In addition, the corresponding adsorbed 2-chlorophenoxy moiety was found to be more stable than a vacuum 2-chlorophenoxy radical by about 0.76 eV. Despite these predicted endoergicities, however, we would predict the formation of 2-chlorophenoxy radicals from gaseous 2-chlorophenol over the copper (I) oxide Cu ₂ O(1 1 1)-Cu _CUS surface to be a feasible and important process in the formation of PCDD/Fs in the post-flame region where gas-phase routes are negligible.