Copper Electrodeposition on Pt(111) in the Presence of Chloride and (Bi)sulfate: Rotating Ring-Pt(111)) Disk Electrode Studies

Nenad M. Marković, Hubert A. Gasteiger, Philip N. Ross

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Abstract

Measurements of the kinetics and the flux of copper ions to an electrode surface by meass of a rotating ring-disk electrode (RRDE) are employed for the first time in a study of the underpotential (UPD) and overpotential (OPD) deposition of copper on a Pt(ll)) disk electrode. The RRDPt(111) measurements presented here show definitively that, in the presence of chloride, Cu UPD is a two-stage process, both of them involving Cu deposition. The coverage of Cu and Cl after the first stage of UPD is ca. 0.58 ML (ML = monolayer). There is little or no additional adsorption of chloride ion during the initial stage of Cu UPD. The second stage of Cu UPD is primarily related to the deposition of Cu forming an essentially complete monolayer (≈0.9 ML), accompanied by desorption of approximately 0.1 ML of Cl-. In pure perchloric acid, Cu electrodeposition is a slow, kinetically controlled process. The presence of either (bi)-sulfate and/or chloride in the electrolyte significantly enhances the kinetics of Cu deposition. This enhancement is suggested to be related to the tendency of large anions to perturb the solvation shell of strongly hydrated Cu2+ ions. In electrolyte with 10-2 M CI-, Cu2+ is partially reduced to Cu+ in the vicinity of the OPD potential region due to its complexation with CI-. The observed potential regions of stability for Cu2+, Cu+, and Cu0 weee confirmed by a thermodynamic analysis.

Original languageEnglish
Pages (from-to)4098-4108
Number of pages11
JournalLangmuir
Volume11
Issue number10
DOIs
StatePublished - 1 Oct 1995
Externally publishedYes

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