Synthesis and characterization of nickel nanoparticles dispersed in imidazolium ionic liquids

Abstract

The diameter and size-distribution of Ni nanoparticles prepared by the decomposition of [bis(1,5-cyclooctadiene)nickel(0)] organometallic precursor dissolved in 1-alkyl-3-methylimidazolium N-bis(trifluoromethanesulfonyl) amide ionic liquids depend on the length of the alkyl side-chain of the imidazolium ring. The increase of the organization range order of the ionic liquid that increases with that of the alkyl side-chain (from n-butyl to n-hexadecyl) induces the formation of nanoparticles with a smaller diameter and size-distribution. The cubic fcc Ni nanoparticles with 4.9 +/- 0.9 to 5.9 +/- 1.4 nm in mean diameter and monomodal size-distribution thus prepared are probably composed of a small cap layer of NiO around a core of Ni metal. The contribution of the oxide layer also depends on the medium i.e. the metal oxide ratio increases in salts containing four to eight carbons on their side-chains and then decreases as the number of carbons increases. The Ni nanoparticles dispersed in the ionic liquids are active catalysts for the hydrogenation of olefins under relatively mild reaction conditions.

Ionic Liquids for the Synthesis and Stabilization of Metal Nanoparticles

“…Hydrogen as a reagent was used to hydrogenate the ligands COD and COT to cyclooctane which was subsequently lost from the Ru(0) or Ni(0) metal atom [86,97,98,214]. [Ru(COD)(COT)] or [Ni(COD) 2 ] were dissolved in imidazolium based ILs and the mixture heated under 4 bar of hydrogen under different conditions to obtain metal nanoparticles (Table 5).…”

Ionic Liquid Surface Composition Controls the Size of Gold Nanoparticles Prepared by Sputtering Deposition

“…It has been proposed recently that the nanoparticle growth process resulting from the reduction or decomposition of metal complexes is controlled by the local concentration of the precursor and consequently limited to the size and shape of the IL polar or nonpolar domains. 19 In particular, a relationship has been demonstrated between the size of IL nonpolar domains calculated by molecular dynamics simulations and nanoparticle size measured by TEM. 20 Similarly, the volume of the polar domains of in the imidazolium ILs may be controlled by changing the anion volume.…”

Palladium nanoparticle catalysts in ionic liquids: synthesis, characterisation and selective partial hydrogenation of alkynes to Z-alkenes

“…7,22 The IL forms a protective layer, which is probably composed of imidazolium aggregates located immediately adjacent to the nanoparticle surface, providing both steric and electronic protection against aggregation and/or agglomeration. 23,24 Palladium is among the most popular transition metal nanoparticles used in catalysis and widely used for a significant number of synthetic transformations. 25 Several synthetic methods have been reported regarding the preparation of stable Pd-NPs.…”