XPS and STM studies of the oxidation of hydrogen chloride at Cu(100) surfaces

SURFACE SCIENCE

卷:650

Article

Altass, Hatem³  Carley, Albert F.^1,2  Davies, Philip R.^1,2  Davies, Robert J.⁴ 

[1] Cardiff Univ, Sch Chem, Main Bldg,Pk Pl, Cardiff CF10 3AT, S Glam, Wales

[2] Cardiff Univ, Cardiff Catalysis Inst, Main Bldg,Pk Pl, Cardiff CF10 3AT, S Glam, Wales

[3] Umm Al Qura Univ, Dept Chem, Fac Sci Appl, Mecca 21955, Saudi Arabia

[4] Univ London Imperial Coll Sci Technol & Med, Dept Mat, London SW7 2AZ, England

关键词: HCl;    Cu(100);    Oxidation;    Chlorination;    XPS;    Copper chloride;   

DOI  :  10.1016/j.susc.2015.12.024

来源: Elsevier

【 摘 要 】

The dissociative chemisorption of HCl on clean and oxidized Cu(100) surfaces has been investigated using x-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM). Whereas the dissociation of HCl at the clean surface is limited to the formation of a (root 2 x root 2)-R45 degrees Cl(a) monolayer, the presence of surface oxygen removes this barrier, leading to chlorine coverages up to twice that obtained at the clean surface. Additional features in the STM images that appear at these coverages are tentatively assigned to the nucleation of CuCl islands. The rate of reaction of the HCl was slightly higher on the oxidized surface but unaffected by the initial oxygen concentration or the availability of clean copper sites. Of the two distinct domains of adsorbed oxygen identified at room temperature on the Cu(100) surfaces, the (root 2 x root 2)-R45 degrees structure reacts slightly faster with HCl than the missing row (root 2 x 2 root 2)-R45 degrees O(a) structure. The results address the first stages in the formation of a copper chloride and present an interesting comparison with the HCl/O(a) reaction at Cu(110) surfaces, where oxygen also increased the extent of HCl reactions. The results emphasize the importance of the exothermic reaction to form water in the HCl/O(a) reaction on copper. (C) 2016 The Authors. Published by Elsevier B.V.

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