TY - JOUR
T1 - Strong correlations between structural order and passive state at water-copper oxide interfaces
AU - Narayanan, Badri
AU - Deshmukh, Sanket A.
AU - Sankaranarayanan, Subramanian K.R.S.
AU - Ramanathan, Shriram
N1 - Funding Information:
Use of the Center for Nanoscale Materials was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences , under Contract No. DE-AC02–06CH11357 . This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 . An award of computer time was provided by the Innovative and Novel Computational Impact on Theory and Experiment (INCITE) program. This research used resources of the Argonne Leadership Computing Facility, which is a DOE Office of Science User Facility supported under Contract DE-AC02-06CH11357 .
PY - 2015/10/10
Y1 - 2015/10/10
N2 - A fundamental understanding of coupled electrochemical processes including metal dissolution, structural evolution and solvation dynamics at the atomic level is of interest to corrosion research and electrochemistry in general. Using molecular dynamics (MD) simulations based on a reactive force field (ReaxFF), we evaluate the impact of non-stoichiometry in a model system of copper oxide passive films on the local fluctuation of the chloride ion density and structure and dynamics of interfacial water layers. We investigate (a) the interplay of oxygen content in the passive oxide film and the solvation dynamics of halide ions in the aqueous interfacial layers during breakdown of the oxide film, and (b) their combined effects on the dissolution kinetics of copper and adsorption of chloride ions on the copper-oxide surface. We demonstrate that the solvation behavior, particularly near the oxide/aqueous medium interface, is strongly correlated with the interfacial chloride ion concentration, which in turn is influenced by the oxygen stoichiometry in the passive oxide. Residence probability and hydrogen-bond correlations show that water present in the aqueous media forms ordered layers on oxide films with high oxygen content; and as the oxygen content is reduced, this order gets disrupted due to increased chloride ion adsorption. Interfacial molecular order is, therefore, strongly correlated with stoichiometry of the passive oxide film.
AB - A fundamental understanding of coupled electrochemical processes including metal dissolution, structural evolution and solvation dynamics at the atomic level is of interest to corrosion research and electrochemistry in general. Using molecular dynamics (MD) simulations based on a reactive force field (ReaxFF), we evaluate the impact of non-stoichiometry in a model system of copper oxide passive films on the local fluctuation of the chloride ion density and structure and dynamics of interfacial water layers. We investigate (a) the interplay of oxygen content in the passive oxide film and the solvation dynamics of halide ions in the aqueous interfacial layers during breakdown of the oxide film, and (b) their combined effects on the dissolution kinetics of copper and adsorption of chloride ions on the copper-oxide surface. We demonstrate that the solvation behavior, particularly near the oxide/aqueous medium interface, is strongly correlated with the interfacial chloride ion concentration, which in turn is influenced by the oxygen stoichiometry in the passive oxide. Residence probability and hydrogen-bond correlations show that water present in the aqueous media forms ordered layers on oxide films with high oxygen content; and as the oxygen content is reduced, this order gets disrupted due to increased chloride ion adsorption. Interfacial molecular order is, therefore, strongly correlated with stoichiometry of the passive oxide film.
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U2 - 10.1016/j.electacta.2015.03.221
DO - 10.1016/j.electacta.2015.03.221
M3 - Article
AN - SCOPUS:84943455352
SN - 0013-4686
VL - 179
SP - 386
EP - 393
JO - Electrochimica Acta
JF - Electrochimica Acta
ER -