Synthesis of metal-fluoride nanoparticles supported on thermally reduced graphite oxide

Abstract

Metal-fluoride nanoparticles, (MFx-NPs) with M = Fe, Co, Pr, Eu, supported on different types of thermally reduced graphite oxide (TRGO) were obtained by microwave-assisted thermal decomposition of transition-metal amidinates, (M{MeC[N(iPr)]2}n) or [M(AMD)n] with M = Fe(II), Co(II), Pr(III), and tris(2,2,6,6-tetramethyl-3,5-heptanedionato)europium, Eu(dpm)3, in the presence of TRGO in the ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]). The crystalline phases of the metal fluorides synthesized in [BMIm][BF4] were identified by powder X-ray diffraction (PXRD) to be MF2 for M = Fe, Co and MF3 for M = Eu, Pr. The diameters and size distributions of MFx@TRGO were from (6 ± 2) to (102 ± 41) nm. Energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) were used for further characterization of the MFx-NPs. Electrochemical investigations of the FeF2-NPs@TRGO as cathode material for lithium-ion batteries were evaluated by galvanostatic charge/discharge profiles. The results indicate that the FeF2-NPs@TRGO as cathode material can present a specific capacity of 500 mAh/g at a current density of 50 mA/g, including a significant interfacial charge storage contribution. The obtained nanomaterials show a good rate capacity as well (220 mAh/g and 130 mAh/g) at a current density of 200 and 500 mA/g, respectively.

Synthesis of plasmonic Fe/Al nanoparticles in ionic liquids

“…The [NTf 2 ] À anion was chosen because of its hydrophobic character and its hydrothermal stability, since the anion [BF 4 ] À is well known to form metal-uoride nanoparticles. 53,54 The IL cations can have a profound effect on the stabilization, size and size distribution of the obtained metal nanoparticles. 55,57 Imidazolium-ILs, in particular with the cation [BMIm] + are well established for the synthesis of small NPs.…”

Synthesis of rare-earth metal and rare-earth metal-fluoride nanoparticles in ionic liquids and propylene carbonate

“…Schmitz et al synthesized REF 3 -NPs with RE = Pr, Eu, supported on different types of thermally reduced graphite oxide (TRGO) in [BMIm][BF 4 ] [ 12 ]. The formation of REF 3 -NPs is due to the [BF 4 ] − anion in the IL [BMIm][BF 4 ].…”

“…The formation of REF 3 -NPs is due to the [BF 4 ] − anion in the IL [BMIm][BF 4 ]. The [BF 4 ] – anion hydrolyzes or decomposes to fluoride F − with small amounts of residual water in the IL (30 ppm) which is very difficult to remove from hydrophilic [BMIm][BF 4 ] [ 12 , 42 ]. It is also known that the [BF 4 ] − anion decomposes to fluoride at high temperature [ 43 ].…”

“…Alternatively, reactive metal atoms or metal clusters may also abstract fluoride from [BF 4 ] − anions. ILs are not only solvents but can also be reactants, e.g., [BMIm][PF 6 ] in the synthesis of A 2 SiF 6 nanoparticles (A = Li, Na, K, Rb, Cs) [ 46 ], in the synthesis of MF x nanoparticles (M = Mn, Fe, Co, Pr, Eu) from the decomposition of transition-metal amidinates in [BMIm][BF 4 ] [ 12 , 42 ] or in the synthesis of metal-fluoride nanoparticles from metal acetate (hydrate) in ethylene glycol and an excess of [BMIm][BF 4 ] [ 47 ].…”

“…An alternative method for synthesizing rare-earth metal-fluoride nanoparticles is the use of rare-earth metal amidinates as precursors [ 9 – 12 ]. Metal amidinates are coordination compounds [ 13 – 14 ] and used, for example, as catalysts in the polymerization of olefins [ 15 – 16 ] and as precursors in chemical vapor (CVD) processes of rare-earth materials such as oxides and nitrides [ 17 – 19 ].…”