Microelectrode evaluation of transition metal-aluminum alloy electrodepositions in chloroaluminate ionic liquids

• Published in: Journal of the Electrochemical Society 1998-05, Vol.145 (5), p.1598-1607
• Main Authors: CARLIN, R. T, DE LONG, H. C, FULLER, J, TRULOVE, P. C
• Format: Article
• Language: English
• Subjects: Applied sciences; Chemistry; Electrochemistry; Exact sciences and technology; General and physical chemistry; High temperature electrochemistry (including molten salts); Metallic coatings; Metals. Metallurgy; Production techniques; Surface treatment
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/1.1838524

Chronoamperometric data collected at a 250 mu m tungsten microelectrode were analyzed under near-steady-state conditions to determine the composition of MAl sub x alloys (M=Co, Ni, Fe, Cu, and Ag) electrodeposited from 1.5:1.0 AlCl sub 3 :1-ethyl-3-methylimidazolium chloride room temperature ionic liquids. The analysis method relied on the fact that these alloys are produced by an underpotential deposition mechanism. Results were consistent with previous studies showing that the CoAl sub x , FeAl sub x , and CuAl sub x systems tended to produce alloys with xapprox =1. Analysis of the NiAl sub x data was complicated by kinetic phenomena, while data analysis of the AgAl sub x system was precluded by dendritic growth of the electrodeposit. All the alloy systems showed complex anodic stripping voltammetric behavior, and the nature of the oxidation processes (e.g., metal anodization, alloy anodization, or selective dealloying) are different for electrodeposits produced in specific potential regimes. Nonlinear curve fitting of the chronoamperometric data to the appropriate short-time and long-time equations gave diffusion coefficients from 3.9x10 exp -7 to 8.3x10 exp -7 cm exp 2 s exp -1 for the transition metal ions in the ionic liquid electrolyte at ca. 22 deg C.