Electroreduction of tantalum fluoride in a room temperature ionic liquid at variable temperatures

• Published in: Physical chemistry chemical physics : PCCP 2005-06, Vol.7 (11), p.2333-2339
• Main Authors: ZEIN EL ABEDIN, S, FARAG, H. K, MOUSTAFA, E. M, WELZ-BIERMANN, U, ENDRES, F
• Format: Article
• Language: English
• Subjects: Chemistry; Exact sciences and technology; General and physical chemistry
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/b502789f

The present paper deals with the electroreduction of TaF5 in the room temperature ionic liquid 1-buty-1-methyl-pyrrolidinium bis(tri-fluoromethylsulfonyl)imide ([BMP]Tf2N) at different temperatures for the sake of electrodeposition of tantalum. The study was carried out using cyclic voltammetry and chronoamperometry measurements complemented by SEM-EDAX and XRD investigations. In situ scanning tunneling microscopy and I-U tunneling spectroscopy were also utilized for characterization of the electrodeposits. The results show that, in addition to the formation of insoluble compounds, Ta can be electrodeposited in the ionic liquid ([BMP]Tf2N) containing 0.5 M TaF5 at 200 degrees C on polycrystalline Pt and Au(111) electrodes. By addition of LiF to the electrolyte, the quality and the adherence of the electrodeposit were found to be improved. An in situ I-U tunneling spectrum with about 300 nm thickness of the electrodeposit shows metallic behaviour indicating the formation of elemental tantalum. Moreover, the XRD patterns of the electrodeposit, obtained potentiostatically at -1.8 V (vs. Pt) in ([BMP]Tf2N) containing 0.25 M TaF5 and 0.25 M LiF on Pt electrode at 200 degrees C, show the characteristic patterns of crystalline tantalum.