Green Electrodeposition of Common Lanthanide Rare Earth Metals Using Ionic Liquids: Challenges and Opportunities

Lanthanides are rare Earth elements (REEs) positioned in the f-block of the periodic table and exhibit unique electronic configurations that confer exceptional magnetic, optical, and electronic properties. Consequently, they are pivotal components spanning from hard disk drives to renewable energy systems. The increasing demand for REEs in various modern technologies has driven the need for a secure and sustainable production process. Traditional methods of REEs extraction and processing, such as molten salt electrolysis, are energy-intensive and generate toxic waste, necessitating the development of alternative low-temperature separation processes. Ionic liquids (ILs), or low-temperature molten salts, have emerged as promising media for REEs electrodeposition owing to their wide potential window, excellent ionic conductivity, thermal stability, and environmental friendliness. In this review, electrochemical behavior and electrodeposition of some common REEs (Y, La, Pr, Nd, Sm, Eu, Gd, and Dy) in various ILs, along with selected cases of similar types of electrolytes called deep eutectic solvents (DESs), are discussed. The comprehensive analysis of the electrochemical behavior and deposition conditions of REEs in ILs offers valuable insights into sustainable industrial-scale REEs production in an environment-friendly way.