Electrochemical Behavior of Bis(acetylacetonato)platinum(II) Complex in an Amide-Type Ionic Liquid

Abstract

Electrochemical behavior of bis(acetylacetonato)platinum(II) (Pt(acac) 2 ) was investigated in an amide-type ionic liquid, trimethylhexylammonium bis(trifluoromethylsulfonyl)amide (TMHATFSA), at various temperatures. Ultraviolet visible spectroscopy revealed the existence of Pt(acac) 2 having square planar geometry in TMHATFSA. The electrochemical reduction of Pt(acac) 2 to Pt(0) was considered to occur with formation of some intermediate species of Pt by cyclic voltammetry. Potentiostatic cathodic reduction on a glassy carbon electrode in TMHATFSA containing Pt(acac) 2 at −1.7 V at 130 • C resulted in deposition of metallic Pt, which was confirmed by scanning electron microscopy and energy dispersive X-ray spectroscopy. In addition, formation of Pt nanoparticles dispersed in the ionic liquid after potentiostatic cathodic reduction was confirmed by transmission electron microscopy and electron diffraction. The sizes of the Pt nanoparticles were found to depend on the reduction potential.Platinum (Pt) has been known to be one of the important catalysts for various chemical and electrochemical reactions. Pt is well known to be used as the catalyst in water electrolysis, hydrogenation of hydrocarbon, fuel cell, and so on. The electrodeposition method has been proved to be useful for preparation of materials with controlled size and morphology. To date, efforts have been focused on preparation of Pt catalysts with high surface area to achieve high catalytic activity. Numerous studies on electrochemical behavior of Pt film and/or nanoparticles in aqueous solutions are available in the literature. [1][2][3][4][5][6][7][8] However, the previous attempts on electrodeposition of Pt in aqueous solutions were often accompanied with hydrogen evolution due to the high catalytic activity of Pt. The co-deposition of hydrogen during Pt electrodeposition leads to embrittlement of Pt. This necessitates the utilization of non-aqueous electrolytes including ionic liquids.Ionic liquids have drawn intensive interest as an alternative of molecular solvents due to their excellent properties, which include acceptable ionic conductivity, negligible vapor pressure, and less inflammability. Aprotic ionic liquids having wide electrochemical potential windows are expected to be the alternative media for deposition of metals compared with conventional organic electrolytes. 9,10 In addition, preparation of nanoparticles in ionic liquids has received increasing attention in recent years. 11-17 Among the ionic liquids, the chloroaluminate or chlorozincate ionic liquids have received special attention for metal electrodeposition. However, the application of these chlorometallate ionic liquids was limited due to their water sensitivity and co-deposition of Al or Zn during reduction of desired metals. Based on these issues, air and water stable bis(trifluoromethylsulfonyl)amide (TFSA − )-based ionic liquids have been considered promising media for electrodeposition of various metals and metal nanoparticles. 18-25 Electrodeposition of Pt and its allo...

Redox Reaction of Tris(acetylacetonato)iron(III) Complex in an Amide-type Ionic Liquid

“…[14][15][16] We have reported that the metal complexes with acac ¹ , such as Pd(acac) 2 and Pt(acac) 2 , are stable in TFSA ¹ -based ionic liquids. [17][18][19] In the present study, the redox properties of Fe(acac) 3 were investigated in BMPTFSA.…”

Electrodeposition of Metals and Preparation of Metal Nanoparticles in Nonaqueous Electrolytes and Their Application to Energy Devices

“…Metallic Pt was also obtained from Pt(acac)2 in Pyr1,4TFSA and N,N,N-trihexyl-N-methylammonium TFSA (N1666TFSA). 46,49 The results indicate that acac complexes are useful non-halogenated precursors for the electrodeposition of Pd and Pt.…”

“…We investigated the electrodeposition of various metals and the electrochemical behaviors of metal ions using RTILs composed of aliphatic cations and TFSA anion, which have a high reduction stability and relatively low viscosity. [42][43][44][45][46][47][48][49][50][51][52][53] Pd and Pt are two of the important metals used in scientific and industrial fields owing to their good physical and chemical properties such as corrosion and wear resistance. Therefore, the electrodeposition of Pd and Pt from RTILs has been extensively investigated; however, the precursor metal salts were limited to halogeno complexes.…”

“…54,55 To reduce the halogen contamination of the deposits, we investigated the electrodeposition of Pd and Pt from acetylacetonate (acac) complexes used as precursors. 42,46,49 The cyclic voltammograms of a GCE in 1-butyl-1methylpyrrolidinium TFSA (Pyr1,4TFSA) without and with 5 mM Pd(acac)2 at room temperature are shown in Fig. 3.…”

Application of Ionic Liquids in Electrochemistry—Recent Advances

“…Sultana et al [ 61 ] used N -trimethyl- N -hexylammonium bis(trifluoromethylsulfonyl)amide, [N 1116 ][NTf 2 ], to study the electrochemical behaviour of an acetylacetonate (acac) platinum(II) complex, [Pt(acac) 2 ], as function of temperature ( Figure 13 ). A cathodic peak corresponding to the reduction of Pt(II) to Pt(0) and consequent electrodeposition of this metal on the electrode was found to depend on the diffusion of Pt(acac) 2 in the [N 1116 ][NTf 2 ] IL.…”