Electrodeposition of cobalt from a hydrophobic room-temperature molten salt system

The electrodeposition of cobalt was investigated in a hydrophobic room-temperature molten salt, 1-n-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMPTFSI), containing Co(TFSI)₂ as a Co source. The cathodic reduction wave of Co (II) species was confirmed by cyclic voltammetry. The electrodeposit obtained by the potentiostatic reduction on a nickel substrate was found to be metallic Co by both XPS and EDX analyses. The diffusion coefficient of Co(II) was estimated to be 1.0 × 10 ^-7 cm² s^-1 at 27.8°C. The electrodeposition of Co on the Pt sub-strate seemed to involve the three-dimensional instantaneous nucleation under diffusion control.