Synthesis of Metal Nanoparticles and Metal Fluoride Nanoparticles from Metal Amidinate Precursors in 1-Butyl-3-Methylimidazolium Ionic Liquids and Propylene Carbonate.

ABSTRACT: Decomposition of transition-metal amidinates [M{MeC(NiPr)₂} _n ] [M(AMD) _n ; M=Mn^II, Fe^II, Co^II, Ni^II, n=2; Cu^I, n=1) induced by microwave heating in the ionic liquids (ILs) 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF₄]), 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm][PF₆]), 1-butyl-3-methylimidazolium trifluoromethanesulfonate (triflate) ([BMIm][TfO]), and 1-butyl-3-methylimidazolium tosylate ([BMIm][Tos]) or in propylene carbonate (PC) gives transition-metal nanoparticles (M-NPs) in non-fluorous media (e.g. [BMIm][Tos] and PC) or metal fluoride nanoparticles (MF₂-NPs) for M=Mn, Fe, and Co in [BMIm][BF₄]. FeF₂-NPs can be prepared upon Fe(AMD)₂ decomposition in [BMIm][BF₄], [BMIm][PF₆], and [BMIm][TfO]. The nanoparticles are stable in the absence of capping ligands (surfactants) for more than 6?weeks. The crystalline phases of the metal or metal fluoride synthesized in [BMIm][BF₄] were identified by powder X-ray diffraction (PXRD) to exclusively Ni- and Cu-NPs or to solely MF₂-NPs for M=Mn, Fe, and Co. The size and size dispersion of the nanoparticles were determined by transmission electron microscopy (TEM) to an average diameter of 2(±2) to 14(±4)?nm for the M-NPs, except for the Cu-NPs in PC, which were 51(±8)?nm. The MF₂-NPs from [BMIm][BF₄] were 15(±4) to 65(±18)?nm. The average diameter from TEM is in fair agreement with the size evaluated from PXRD with the Scherrer equation. The characterization was complemented by energy-dispersive X-ray spectroscopy (EDX). Electrochemical investigations of the CoF₂-NPs as cathode materials for lithium-ion batteries were simply evaluated by galvanostatic charge/discharge profiles, and the results indicated that the reversible capacity of the CoF₂-NPs was much lower than the theoretical value, which may have originated from the complex conversion reaction mechanism and residue on the surface of the nanoparticles.

SUBMITTER: Schutte K 

PROVIDER: S-EPMC5288766 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature