A SECM Study of Heterogeneous Redox Activity at AA2024 Surfaces

Jesse C. Seegmiller, Daniel Buttry

Research output: Contribution to journalArticle

57 Citations (Scopus)

Abstract

Scanning electrochemical microscopy (SECM) was used to spatially resolve the heterogeneous cathodic activity at AA2024 surfaces. Experiments used a 10 μm diameter Pt microelectrode in a solution containing the protonated form of (dimethylamino) methylferrocene [DMAFc+, i.e., the Fe(II) state]. The tip was brought near the alloy surface while held at a potential of 0.65 V vs. SCE, where DMAFc+ is oxidized to DMAFc2+ [i.e., the Fe(III) state]. The AA2024 substrate was held at -0.75 V, where the DMAFc 2+ produced near the probe tip is reduced back to DMAFc+ at regions on the surface that were cathodically active. Lateral variation in the DMAFc+ oxidation current at the tip arises either from a decrease of the diffusive delivery of DMAFc+ to the tip due to proximity to the surface or from a positive feedback mechanism in which the DMAFc2+ that had been oxidized at the probe tip was reduced at the substrate. The images show locally high redox reactivity which is attributed to second phase, intermetallic inclusions. Comparison of the SECM images with scanning electron microscopy-energy dispersive spectroscopy images shows that the regions of high redox reactivity correlate with the locations of the intermetallic particles.

Original languageEnglish (US)
JournalJournal of the Electrochemical Society
Volume150
Issue number9
DOIs
StatePublished - Sep 2003
Externally publishedYes

Fingerprint

Microscopic examination
microscopy
Scanning
scanning
Intermetallics
intermetallics
reactivity
Microelectrodes
Substrates
positive feedback
probes
Energy dispersive spectroscopy
proximity
delivery
Feedback
Oxidation
Scanning electron microscopy
Oxidation-Reduction
inclusions
oxidation

ASJC Scopus subject areas

  • Electrochemistry
  • Surfaces, Coatings and Films
  • Surfaces and Interfaces

Cite this

A SECM Study of Heterogeneous Redox Activity at AA2024 Surfaces. / Seegmiller, Jesse C.; Buttry, Daniel.

In: Journal of the Electrochemical Society, Vol. 150, No. 9, 09.2003.

Research output: Contribution to journalArticle

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