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Aluminum UPD and Alloy Formation on (111)-Textured Au in AlCl_{3}-EMImCl



Gery R. Stafford, G Haarberg


The kinetics of Al-Au surface alloy formation was examined during Al underpotential deposition (upd) onto (111)-texture Au from Lewis acidic aluminum chloride-1-ethyl-3-methlimidazolium chloride (AlCl_{3}-EMImCl)using linear sweep stripping voltammetry following potentiostatic deposition. The upd of Al on Au is a two-step process. The charge associated with the initial step is about 120 micronC/cm^{2}, and may be due to the reductive decomposition of AlCl_{4} that is known to be adsorbed on the Au surface. The charge measured for the complete upd process is about 1200 microC/Cm^{2}, equivalent to that expected for a monolayer of Al on Au(111) with a roughness factor of 1.8. Following completion of the Al monolayer, two alloys are formed. The first is only present at short times and is restricted to the near surface while the second is the more stable of the two and extends into the Au substrate. The magnitude of the tensile stress change observed experimentally is close to that calculated from the elastic strain associated with the change in molar volume and using the reaction kinetics obtained from stripping voltammetry.
Journal of the Electrochemical Society


Stafford, G. and Haarberg, G. (2008), Aluminum UPD and Alloy Formation on (111)-Textured Au in AlCl_{3}-EMImCl, Journal of the Electrochemical Society (Accessed February 27, 2024)
Created March 20, 2008, Updated March 5, 2020