(Invited) Ultrasound Application and Multi-Step Reactions in Electrodeposition of Refractory Metals

Abstract

This contribution discusses the application of ultrasound in ionic liquids (ILs) and its effect on refractory metal deposition as well as the particular electrochemistry of NbCl5 in TFSI based ILs. A systematic study was carried out studying electrochemical reactions and electrolyte decomposition in the presence of ultrasound. Extended application of ultrasound induced partial IL decomposition and formation of solid precipitates. Electrochemical reactions in ILs were enhanced by ultrasound application. Especially the application of short ultrasound pulses at elevated temperatures increased electrochemical reaction rates. The reduction of NbCl5 from BMP and OMP TFSI ILs is characterized by five separate distinct reduction and corresponding oxidation steps. This system was studied in depth using the electrochemical quartz crystal microbalance technique, revealing strong changes in the electrolyte properties close to the interface.