Microelectrode Evaluation of Transition Metal‐Aluminum Alloy Electrodepositions in Chloroaluminate Ionic Liquids

Abstract

Chronoamperometric data collected at a 250 μm tungsten microelectrode were analyzed under near‐steady‐state conditions to determine the composition of alloys (M = Co, Ni, Fe, Cu, and Ag) electrodeposited from 1.5:1.0 :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 and systems tended to produce alloys with x ≈ 1. Analysis of the data was complicated by kinetic phenomena, while data analysis of the 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 to for the transition metal ions in the ionic liquid electrolyte at ca. 22°C.