Low-temperature electrochemical codeposition of aluminum-neodymium alloy in a highly stable solvate ionic liquid

Abstract

A highly stable solvate ionic liquid comprising a 2:1 (mol/mol) mixture of ethylene carbonate (EC) and AlCl3 was used for near room-temperature electrochemical codeposition of an Al-Nd alloy using chlorides as precursors. This liquid is low-cost, easy to prepare, and has high electrochemical stability. The ionic structure was analyzed by 27Al nuclear magnetic resonance; Raman spectroscopy and the dissolution phenomenon was studied by ultraviolet-visible spectroscopy. The dissolution mechanism of NdCl3 in this solvate ionic liquid was derived as 3[AlCl2(EC)n]+\u2009+\u20092NdCl3 ⇆ 2Nd(III)\u2009+\u20093[AlCl4]−\u2009+\u20093nEC. Cyclic voltammetry was used to explore the electrochemical behavior of Nd- and Al-containing species, revealing that the reduction of Al and Nd are both one-step electron-gaining processes. X-ray diffraction confirmed that an Al-Nd alloy can be obtained in the form of thermally stable Al2Nd by potentiostatic electrolysis at high cathode overpotential (−\u20093.5\xa0V vs. Al). Although the deposited alloy layer is not dense, Al-containing solvate ILs have immense potential in green electrometallurgy because of their higher tunability and similar properties to ILs.