Electrodeposition of nanomaterials in air and water stable ionic liquids

I&EC 130

Sherif Zein El Abedin, sherif.zein@tu-clausthal.de, Institute of Metallurgy, Clausthal University of Technology, Robert-Koch-Str. 42, Clausthal-Zellerfeld, 38678, Germany and Frank Endres, frank.endres@tu-clausthal.de, chair of electrochemistry, Clausthal University of Technology, Robert-Koch-Strasse 42, D-38678 Clausthal-Zellerfeld, Germany.
Ionic liquids, especially air and water stable, have attracted considerable attention since they have extraordinary physical properties superior to those of water or organic solvents. They have extremely large electrochemical windows, more than five volts, and hence they give access to elements which cannot be electrodeposited from aqueous solutions such as, e.g., Al, Mg, Ta, Ge and Si. Moreover, the problems associated with hydrogen ions in conventional protic solvents can be eliminated in ionic liquids because ionic liquids are normally aprotic. In this paper, we report on the electrodeposition of tantalum on different substrates such as, single crystalline gold Au(111), polycrystalline platinum, NiTi alloy and stainless steel in the water and air stable ionic liquid 1-butyl-1-methyl-pyrrolidinium bis (tri-fluoromethylsulfonyl) imide ([BMP]Tf2N) containing TaF5 as a source of tantalum. 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 oC. The XRD patterns of the electrodeposit show the characteristic patterns of crystalline tantalum. Moreover, it was found that the deposition of an only 500 nm thick film of Ta on NiTi alloy improves its corrosion resistance which, in turn, enhances its biocompatibility. We report also the first results of the electrodeposition of nano- and microcrystalline aluminium in some water and air stable ionic liquids namely, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl) imide [BMP]Tf2N, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide [EMIm] Tf2N and trihexyl-tetradecyl phosphonium bis(trifluoromethylsulfonyl) imide (P14,6,6,6 Tf2N).