Anodic Dissolution and Electropolishing of Titanium in an Amide-Type Ionic Liquid Containing Halide Ions

Anodic dissolution of titanium was investigated in an amide-type ionic liquid, 1-butyl-1-methylpyrrolidinium bis(trifluoromethyl-sulfonyl)amide (BMPTFSA) in the presence of halide ions, Cl – and Br – . Electropolishing of Ti was possible in the presence of Cl – at 353 K, suggesting that the surface of a Ti electrode with the native oxide layer was activated by Cl – . The dissolved species of Ti after anodic dissolution of Ti at 0 V vs. Ag|Ag(I) was found to be tetravalent [TiCl 6 ] 2– , because the applied potential was more positive than the redox potential of [TiCl 6 ] 2– /[TiCl 6 ] 3– . The morphology of a Ti electrode changed after potentiostatic anodic oxidation at –0.5 V in BMPTFSA containing BMPBr, indicating that anodic dissolution of Ti was possible in the presence of Br – .