The Electrodeposition of Al-Cu Alloys from Room-Temperature Chloroaluminate Electrolytes

Published

October 1, 1999

Author(s)

Gery R. Stafford, V D. Jovic, Thomas P. Moffat

Abstract

The electrodeposition of Cu-Al alloys, as well as the underpotential deposition (UPD) of Al onto Cu(lll), were investigated in acidic aluminum chloride/1-methyl-3-ethylimidazolium chloride ambient temperature molten salt. It was shown that it is possible to produce Cu-Al alloy deposits at potentials positive of that corresponding to the electrodeposition of bulk Al. The onset of Al codeposition was found to occur at approximately 0.30 V versus the Al(III)/Al couple, and the Cu-Al alloy composition was found to be independent of the Cu(I) concentration, reaching a maximum value of 43% atomic fraction Al at 0 V. Alloy deposition potentials based on free energy calculations are in good agreement with those observed experimentally for Zn-Al, Cu-Al, Co-Al, and Fe-Al deposited at room temperature and Ni-AL deposited at 150 C from an aluminum chloride/sodium chloride melt. Cyclic voltammograms recorded on Cu(111)clearly indicate that UPD of Al commences at about 0.30 V vs. Al and is characterized by two distinct surface processes. In-situ scanning tunneling microscopy (STM) examination indicates that an ordered ad-layer appears on the Cu(111) surface at potentials positive of the first UPD wave. A possible model representing this structure corresponds to a layer of tetrachloroaluminate ions, oxidatively adsorbed on the Cu(111) surface, with the face of the tetrahedra adjacent to the copper surface.

Citation

International Symposium on Molten Salts

Volume

99

Issue

# 41

Pub Type

Journals

Keywords

Cu-Al alloys, electrodeposition, free energy, room-temperature molten salt, UPD of Al

Citation

Stafford, G. , Jovic, V. and Moffat, T. (1999), The Electrodeposition of Al-Cu Alloys from Room-Temperature Chloroaluminate Electrolytes, International Symposium on Molten Salts (Accessed May 15, 2024)