Electrodeposition of nanoscaled palladium from hydrophobic ionic liquid

Electrodeposition of palladium has been investigated in a hydrophobic ionic liquid, 1-butyl-1methylpyrrolidinium bis(trifluoromethylsulfonyl) imide (BMPTFSI) ionic liquid containing a palladium halide complex, [PdCl4](2-) or [PdBr4](2-), at various temperatures. The diffusion coefficient of [PdCl4](2-) at 25 degrees C was similar to 10(-7) cm(2) s(-1), which was slightly smaller than that of [PdBr4](2-). The electrodeposits obtained from [PdCl4](2-) were smoother and finer than those from [PdBr4](2-). The grain size of the electrodeposits was, 40 nm even at 120 degrees C, suggesting the crystal growth is suppressed in the ionic liquid. The current efficiency of the electrodeposition of palladium from [PdCl4](2-) was, 80%, probably due to the dispersion of palladium metal in the ionic liquid.