Electroanalytical Study of Active Species to Deposit Ti Alloy from 1-Butyl-3-Methylimidazolium Chloride-Aluminum Chloride Ionic Liquid

The electrochemical behavior of titanium-chloroaluminate anion species in Lewis acidic 1-butyl-3-methylimidazolium chloride (BMIC)-aluminum chloride (AlCl₃) ionic liquid (IL) electrolyte with 0.667 AlCl₃ mole fraction is investigated at 383K by cyclic voltammetry (CV), chronoamperometry (CA), and chronopotentiometry (CP). The effect of scan rate on peak potential and peak current, constant current density, constant applied potential, and the electrolyte temperature are discussed. The redox reaction of the Ti²⁺/Ti⁰ deposition from titanium hepta-chloroaluminate ([Ti(Al₂Cl₇)₄]²⁻) anions is a reversible process with a 2-electron transfer while that of Al³⁺/Al⁰ deposition from hepta-chloroaluminate ([Al₂Cl₇]⁻) anions is quasi-reversible with 3-electron transfer. The cyclic voltammograms indicated that the reduction of [Al₂Cl₇]⁻ and [Ti(Al₂Cl₇)₄]²⁻ species to corresponding Al and Ti forms is a diffusion-controlled phenomenon. The diffusion coefficients (D) of the anion-species in BMIC-AlCl₃ IL determined at 383 K using CV and CP methods are 9.74 × 10⁻¹⁰ m² s⁻¹ and 6.36 × 10⁻¹⁰ m² s⁻¹, respectively.