We applied periodic DFT to investigate the adsorption and reaction of HCl and H(2)O molecules on the W(1 1 1) surface. It is shown that the most favorable pathway is HCl((g)) + H(2)O((g)) + W(1 1 1) -> HCl((a)) + H(2)O((a)) + W(1 1 1) -> TS2 -> Cl((a)) + H(2)O((a)) + H((a)) + W(1 1 1) -> TS6 -> Cl((a)) + OH((a)) + 2H((a))+ W(1 1 1) -> TS9 -> Cl((a)) + O((a)) + 3H((a)) + W(1 1 1), and the energy barriers of the aforementioned processes, given in kcal/mol, are 7.62, 14.67 and 25.48, respectively. Eventually, the resulting adsorbed H atoms recombine to form H(2(g)) molecule, which is endothermic by 36.02 kcal/mol. The proposed overall reaction to produce surface- adsorbed chlorine, oxygen and gas-phase H(2) is found to be exothermic by 65.66 kcal/mol and expected to proceed without intrinsic energy barriers. To gain insights into high catalytic activity of the W(1 1 1) surface, we also provided detailed electronic analysis. (C) 2010 Elsevier B.V. All rights reserved.
