Synthesis of Metal Nanoparticles and Metal Fluoride Nanoparticles from Metal Amidinate Precursors in 1-Butyl-3-Methylimidazolium Ionic Liquids and Propylene Carbonate.
Decomposition of transition-metal amidinates [M{MeC(NiPr)2}n] [M(AMD)n; M=MnII, FeII, CoII, NiII,n=2; CuI,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)2decomposition 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.
Institut für Anorganische Chemie und Strukturchemie Heinrich-Heine-Universität Düsseldorf 40204 Düsseldorf Germany.
Kai
K
Schütte
Gemeinschaftslabor für Elektronenmikroskopie RWTH-Aachen Ernst Ruska-Centrum für Mikroskopie und Spektroskopie mit Elektronen 52425 Jülich Germany.
Juri
J
Barthel
Institut für Anorganische Chemie und Strukturchemie Heinrich-Heine-Universität Düsseldorf 40204 Düsseldorf Germany.
Manuel
M
Endres
Institut für Anorganische Chemie und Strukturchemie Heinrich-Heine-Universität Düsseldorf 40204 Düsseldorf Germany.
Marvin
M
Siebels
Physikalisch-Chemisches Institut Justus-Liebig-Universität Gießen 35392 Gießen Germany.
Bernd M
BM
Smarsly
Physikalisch-Chemisches Institut Justus-Liebig-Universität Gießen 35392 Gießen Germany.
Junpei
J
Yue
Institut für Anorganische Chemie und Strukturchemie Heinrich-Heine-Universität Düsseldorf 40204 Düsseldorf Germany.
Christoph
0000-0002-6288-9605
C
Janiak
amidinates; fluorine; ionic liquids; microwave chemistry; nanoparticles