title: Influence of surface vacancy defects on the carburisation of Fe 110 surface by carbon monoxide.
abstract: Adsorption and dissociation of gaseous carbon monoxide (CO) on metal surfaces is one of the most frequently occurring processes of carburisation, known as primary initiator of metal dusting corrosion. Among the various factors that can significantly influence the carburisation process are the intrinsic surface defects such as single surface vacancies occurring at high concentrations due to their low formation energy. Intuitively, adsorption and dissociation barriers of CO are expected to be lowered in the vicinity of a surface vacancy, due to the strong attractive interaction between the vacancy and the C atom. Here the adsorption energies and dissociation pathways of CO on clean and defective Fe 110 surface are explored by means of density functional theory. Interestingly, we find that the O adatom, resulting from the CO dissociation, is unstable in the electron-deficit neighbourhood of the vacancy due to its large electron affinity, and raises the barrier of the carburisation pathway. Still, a full comparative study between the clean surface and the vacancy-defected surface reveals that the complete process of carburisation, starting from adsorption to subsurface diffusion of C, is more favourable in the vicinity of a vacancy defect.
authors.affiliation: Texas A&M University at Qatar, P.O. Box 23874, Doha, Qatar.
authors.forename: Aurab
authors.initials: A
authors.lastname: Chakrabarty
authors.affiliation: Texas A&M University at Qatar, P.O. Box 23874, Doha, Qatar.
authors.forename: Othmane
authors.initials: O
authors.lastname: Bouhali
authors.affiliation: Département de Physique and RQMP, Université de Montréal, Case Postale 6128, Succursale Centre-Ville, Montréal (QC) H3C 3J7, Canada.
authors.forename: Normand
authors.initials: N
authors.lastname: Mousseau
authors.affiliation: UMET, UMR CNRS 8207, ENSCL, Université Lille I, 59655 Villeneuve d'Ascq cédex, France.
authors.forename: Charlotte S
authors.initials: CS
authors.lastname: Becquart
authors.affiliation: Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, P.O. Box 5825 Doha, Qatar.
authors.forename: Fedwa
authors.initials: F
authors.lastname: El-Mellouhi