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

Altass, Hatem, Carley, Albert Frederick, Davies, Philip Rosser ORCID: https://orcid.org/0000-0003-4394-766X and Davies, Robert J. 2015. XPS and STM studies of the oxidation of hydrogen chloride at Cu(100) surfaces. Surface Science 650 , pp. 177-186. 10.1016/j.susc.2015.12.024

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Abstract

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 (√ 2 × √ 2)-R45° 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 (√ 2 × √ 2)-R45° structure reacts slightly faster with HCl than the missing row (√ 2 × 2 √ 2)-R45° 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.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Chemistry
Subjects:	Q Science > QD Chemistry
Publisher:	Elsevier
ISSN:	0039-6028
Funders:	Engineering and Physical Sciences Research Council
Date of First Compliant Deposit:	30 March 2016
Date of Acceptance:	21 December 2015
Last Modified:	06 May 2023 07:58
URI:	https://orca.cardiff.ac.uk/id/eprint/86324

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