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

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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 2O(1 1 1)–Cu CUS. Several vertical and flat orientations have been studied. All of these molecular configurations interact very weakly with the Cu 2O(1 1 1)–Cu CUS surface, an observation which also holds for clean copper surfaces and the Cu 2O(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 2O(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.