Electrochemical Preparation of Platinum Nanoparticles from Bis(acetylacetonato)platinum(II) in Some Aprotic Amide-type Ionic Liquids

Abstract

Electrode reaction of bis(acetylacetonato)platinum(II), Pt(acac)2, and preparation of platinum (Pt) nanoparticles have been studied in 1-R-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (R=butyl, hexyl and decyl, which are abbreviated as BMPTFSA, HMPTFSA and DMPTFSA, respectively) ionic liquids by means of cyclic voltammetry and rotating disk electrode (RDE) method. Pt(acac)2 was suggested to be reduced to Pt via a two-electron transfer process at a glassy carbon electrode. The diffusion coefficient of Pt(acac)2 at 50°C was estimated to be 1.3×10−7cm2s−1 in BMPTFSA, by RDE measurements. It has been demonstrated that Pt nanoparticles were able to be prepared at the glassy carbon RDE by potentiostatic electrolysis at −1.8 and −2.5V in the ionic liquids containing Pt(acac)2. The prepared nanoparticles were characterized by transmission electron microscopy, energy dispersive X-ray spectroscopy and electron diffraction. No pronounced variation in the average particle sizes of Pt was observed with the rotation rates at the RDE, indicating that the average particle size was independent of the rotation rate or current density. Pt nanoparticles of average sizes of 2.1±0.8, 2.8±0.8 and 3.0±0.8nm were obtained after electrolysis at −1.8V with a rotation rate of 1000rpm in BMPTFSA, HMPTFSA and DMPTFSA, respectively, suggested that the average particle size may depend on the kind of the ionic liquid.