Authors: Sack, C; Lustemberg, P; Koller, V; Ganduglia-Pirovano, MV; Over, H

Article.
J. Phys. Chem. C. vol: 122. page: 1932-7447.
Date: AUG 30. 2018.
Doi: 10.1021/acs.jpcc.8b05465.

Abstract:
Ultrathin crystalline CeO2(111) films were grown on Ru(0001) in order to study the interaction of HCl with this surface as a first step of the Deacon reaction with experimental techniques, including low energy electron diffraction (LEED), scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and thermal desorption spectroscopy (TDS) in combination with density functional theory calculations (DFT+U). HCl molecules adsorb dissociatively on CeO2( 111), forming a well-ordered (root 3x root 3)R30 degrees overlayer structure with one Cl and one H per surface unit cell. DFT calculations indicate that HCl adsorption is exothermic by 1.15 eV and proceeds via an acid-base reaction. The mixed overlayer structure is stabilized by Lewis acid-base pairing (similar to 0.4 eV). Stoichiometric CeO2(111) films are likely to be not very active in the Deacon process since at 800 K the recombination of adsorbed H* and Cl* to form HCl is far more preferred over Cl* + Cl* recombination to form the desired product Cl-2..