Stable iron carbide nanoparticle dispersions in [Emim][SCN] and [Emim][N(CN)2] ionic liquids

Varsha Khare; Alexander Kraupner; Alexandre Mantion; Aleksandra Jelicić; Andreas F Thünemann; Cristina Giordano; Andreas Taubert

doi:10.1021/la100775m

Stable iron carbide nanoparticle dispersions in [Emim][SCN] and [Emim][N(CN)2] ionic liquids

Langmuir. 2010 Jul 6;26(13):10600-5. doi: 10.1021/la100775m.

Authors

Varsha Khare¹, Alexander Kraupner, Alexandre Mantion, Aleksandra Jelicić, Andreas F Thünemann, Cristina Giordano, Andreas Taubert

Affiliation

¹ Institute of Chemistry, University of Potsdam, D-14476 Golm, Germany.

PMID: 20426431
DOI: 10.1021/la100775m

Abstract

Dispersions of Fe(3)C nanoparticles in several ionic liquids (ILs) have been investigated. The ILs are based on 1-ethyl-3-methylimidazolium [Emim] and 1-butyl-3-methylimidazolium [Bmim] cations. Anions are ethylsulfate [ES], methanesulfonate [MS], trifluoromethylsulfonate (triflate) [TfO], tetrafluoroborate [BF(4)], dicyanamide [N(CN)(2)], and thiocyanate [SCN]. Among the ILs studied, [Emim][SCN] and [Emim][N(CN)(2)] stand out because only in these ILs have stable and transparent nanoparticle dispersions been obtained. All other ILs lead to blackish, slightly turbid dispersions or to completely nontransparent suspensions, which often contain undispersed sediment. UV/vis spectroscopy, transmission electron microscopy, and X-ray scattering suggest that the reason for the stabilization of the Fe(3)C nanoparticles in [Emim][SCN] is the leaching of traces of iron from the particles (without affecting the crystal structure of the Fe(3)C particles). The resulting particle surface is thus carbon-rich, which presumably favors the stabilization of the particles. A similar explanation can be postulated for [Emim][N(CN)(2)], with the dicyanamide anion also being a good ligand for iron.