Open AccessAnodic Dissolution of Copper in the Acidic and Basic Aluminum Chloride 1-Ethyl-3-methylimidazolium Chloride Ionic Liquid
Author(s) -
Lorlyn Reidy,
Chen Wang,
Charles L. Hussey
Publication year - 2021
Publication title -
journal of the electrochemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.258
H-Index - 271
eISSN - 1945-7111
pISSN - 0013-4651
DOI - 10.1149/1945-7111/abebfa
Subject(s) - chemistry , inorganic chemistry , ionic liquid , chloride , copper , dissolution , electrochemistry , limiting current , potentiometric titration , anodizing , aluminium , catalysis , electrode , organic chemistry
The anodic dissolution of copper was investigated at a copper RDE in the Lewis acidic and basic composition regions of the room-temperature AlCl 3 -EtMeImCl ionic liquid (IL) to assess the utility of chloroaluminate liquids as solvents for the electrochemical machining and electropolishing of copper. In the Lewis acidic IL (60 mol % AlCl 3 ), the dissolution of Cu 0 proceeds under mixed kinetic-mass transport control with an exchange current density of 7.00 mA cm −2 at 306 K and an apparent activation free energy of 19.7 kJ mol −1 . A formal potential of 0.843 V was obtained for the Cu + /Cu 0 reaction from potentiometric measurements. In the basic IL (< 50 mol % AlCl 3 ), potentiometric measurements showed that the oxidation of Cu 0 resulted in the formation of [CuCl 2 ] − . In this case, the formal potential of the [CuCl 2 ] − /Cu 0 reaction is −0.412 V. At small positive overpotentials, the reaction exhibited mixed control and was first order in the chloride concentration, indicating that only a single Cl − is involved in the RDS. However, at more positive overpotentials, the reaction transitions to mass transport control, and a well-defined limiting current is observed for the anodization process. This limiting current scales linearly with the free chloride concentration in the IL.