title: Electroless deposition of platinum nanoparticles in room-temperature ionic liquids.
abstract: The electroless deposition of Pt nanoparticles (Pt-NPs) could be carried out by dissolving potassium tetrachloroplatinate(II) (K2[PtCl4]) in 1-ethyl-3-methylimidazolium (EMI(+)) room-temperature ionic liquids (RTILs) containing bis(trifluoromethylsulfonyl) imide (NTf2(-)) or tetrafluoroborate (BF4(-)) anion and small cations, such as H(+), K(+), and Li(+). In this case, no deposition of Pt-NPs occurred in RTILs without such small cations. The formation of Pt-NPs was only observed in RTILs containing trifluoromethanesulfonimide (HNTf2) and protons at high temperature (≥80 °C) when potassium hexachloroplatinate(IV) (K2[PtCl6]) was dissolved in the RTILs. The obtained Pt-NPs gave a characteristic absorption spectrum of ultrasmall Pt-NPs. The ultrasmall and uniform Pt-NPs of ca. 1-4 nm in diameter were produced and the Pt-NPs/EMI(+)NTf2(-) dispersion was kept stably for several months without adding any additional stabilizers or capping molecules. The identified Fourier-transform patterns along the [0 1 1] zone axis were observed for the TEM images of Pt-NPs. On the basis of the results obtained, a probable mechanism of the electroless formation of Pt-NPs is discussed.
authors.affiliation: Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology , Nagatsuta 4259-G1-5, Midori-ku, Yokohama 226-8502, Japan.
authors.forename: Da
authors.initials: D
authors.lastname: Zhang
authors.forename: Takeyoshi
authors.initials: T
authors.lastname: Okajima
authors.forename: Dalin
authors.initials: D
authors.lastname: Lu
authors.forename: Takeo
authors.initials: T
authors.lastname: Ohsaka