Electrode Reactions of Platinum Bromide Complexes in an Amide-Type Ionic Liquid

Abstract

The electrode reactions of platinum bromide complexes were investigated in an amide-type room-temperature ionic liquid, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (BMPTFSA). Platinum halides were dissolved in BMPTFSA with addition of halide salts of BMP+. Ultraviolet and visible absorption spectra of electrolytes revealed that the coordination environment of Pt(II) and Pt(IV) were [PtBr4]2- and [PtBr6]2- , respectively. The cyclic voltammogram in BMPTFSA containing 10 mM [PtBr6]2- showed two reduction peaks at -1.2 V and -2.6 V. The diffusion coefficients of the [PtBr4]2- and [PtBr6]2- were calculated to be 1.5 × 10-7 and 0.49 × 10-7 cm2 s-1 in BMPTFSA, respectively, by chronoamperometry. Electrodeposition of Platinum in BMPTFSA containing 10 mM [PtBr4]2- was attempted by potentiostatic cathodic reduction at -2.6 V. Nano-particles (2-3 nm in diameter) in the electrolyte after potentiostatic cathodic reduction were observed by transmission electron microscopy. The nano-particles were found to be metallic Platinum by electron diffraction.