Hala K. Farag

Electroreduction of tantalum fluoride in a room temperature ionic liquid at variable temperatures

The present paper deals with the electroreduction of TaF5 in the room temperature ionic liquid 1-buty-1-methyl-pyrrolidinium bis(tri-fluoromethylsulfonyl)imide ([BMP]Tf2N) at different temperatures for the sake of electrodeposition of tantalum. The study was carried out using cyclic voltammetry and chronoamperometry measurements complemented by SEM-EDAX and XRD investigations. In situ scanning tunneling microscopy and I-U tunneling spectroscopy were also utilized for characterization of the electrodeposits. The results show that, in addition to the formation of insoluble compounds, Ta can be electrodeposited in the ionic liquid ([BMP]Tf2N) containing 0.5 M TaF5 at 200 degrees C on polycrystalline Pt and Au(111) electrodes. By addition of LiF to the electrolyte, the quality and the adherence of the electrodeposit were found to be improved. An in situ I-U tunneling spectrum with about 300 nm thickness of the electrodeposit shows metallic behaviour indicating the formation of elemental tantalum. Moreover, the XRD patterns of the electrodeposit, obtained potentiostatically at -1.8 V (vs. Pt) in ([BMP]Tf2N) containing 0.25 M TaF5 and 0.25 M LiF on Pt electrode at 200 degrees C, show the characteristic patterns of crystalline tantalum.

Studies on the synthesis of nano-alumina in air and water stable ionic liquids

In this paper we report on the synthesis of aluminium oxide nanoparticles in two different air and water stable ionic liquids namely, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl) amide [BMP]TFSA and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) amide [EMIm]TFSA. The ionic liquids [BMP]TFSA and [EMIm]TFSA exhibit biphasic behaviour beginning with an AlCl3 concentration of 1.6 mol L–1 and 2.5 mol L–1, respectively. Different aluminium oxides were prepared by the hydrolysis of AlCl3 dissolved in the employed ionic liquids, followed by calcinations. AlCl3·6H2O was found to be the main hydrolysis product of the AlCl3 containing ionic liquids. The as-prepared AlCl3·6H2O is subject to thermal decomposition producing different forms of transition oxides, depending on the original liquid composition. Alumina was also obtained by hydrolysis of as-prepared AlCl3·6H2O by NH4OH solution. Hydrolysis of the upper phase of the biphasic mixture of 3 M AlCl3–[EMIm]TFSA with NH4OH produces transparent alumina which is converted into α-Al2O3 with a low amount of δ-Al2O3 after calcinations at 1000 °C. The formation of pseudoboehmite and γ-Al2O3 as intermediates are observed at 200 °C and 550 °C, respectively. The obtained pseudoboehmite is mesoporous with an average pore diameter of 3.8 nm and a high surface area of 226 m2 g–1. The chloroaluminite obtained by hydrolysis of the homogenous mixture of 1 M AlCl3–[BMP]TFSA undergoes thermal decomposition yielding amorphous alumina at 200 °C, which transforms completely to well crystallized α-Al2O3 at 1000 °C. The obtained α-alumina is porous with an average pore size of about 10 nm. This suggests that the ionic liquid [BMP]TFSA acts as a template and that it decomposes thermally at elevated temperature producing pores.

Sol-gel synthesis of vanadium pentoxide nanoparticles in air-and water-stable ionic liquids

Vanadium pentoxide (V2O5) nanoparticles were synthesized at moderate reaction temperatures by hydrolysis of VO[OCH(CH3)2]3 in two different air- and water-stable ionic liquids with the same anion: 1-butyl-1-methyl pyrrolidinium bis(trifluoromethylsulfonyl)amide ([Py1,4]Tf2N) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([EMIM]Tf2N) via the sol–gel method using acetone and isopropanol either as refluxing solvents or as co-solvents. The cation type of the ionic liquid affects the crystallinity, morphology, and surface area of the produced nanoparticles: [Py1,4]Tf2N gave products with higher crystallinity especially with acetone as a refluxing and co-solvent, while [EMIM]Tf2N gave a clear mesoporous morphology with isopropanol as a refluxing solvent. Ionic liquids affect the key factors (morphology and surface area) that make V2O5 an attractive material as catalyst and/or cathodic material for lithium ion batteries.

Synthesis and Characterization of Rutile and Anatase in Air- and Water-Stable Ionic Liquids with and without Isopropanol as a Cosolvent

Nanocrystalline TiO2 with pure rutile and pure anatase phases was prepared at moderate reaction temperatures by hydrolysis of TiCl4 in different air- and water-stable ionic liquids with the same anion ([Py1,4]Tf2N, [EMIM]Tf2N, and [P14,6,6,6]Tf2N), in isopropanol and in cosolvent of ionic liquid/isopropanol under different reaction conditions. The type of cation in the ionic liquid influences the morphology of the rutile phase: cone-like morphology was obtained in the case of [Py1,4]+ and [P14,6,6,6]+ ions and wormhole-like in the case of [EMIM]+. In the case of anatase, no significant effect was found. The influence of various reaction conditions like acidity of solution, solvent type, precursor type, and precursor concentration on the phase formation and morphology of titania were investigated.

Synthesis of Nanostructured Tin Oxide by Sol–Gel and Sonochemical Approaches in an Ionic Liquid

Abstract The present paper shows a comparative study on the synthesis of nanostructured tin oxide in the ionic liquid 1-ethyl-3-methylimidazolium trifluoromethylsulfonate ([EMIm]TfO) by sol–gel and sonochemical methods. The XRD results of the synthesized materials revealed the formation of single tetragonal phase of SnO2 by sol–gel method whereas a mixture of tetragonal SnO and orthorhombic SnO2 phases was obtained by the sonochemical method. The sonochemical approach led to the formation of finer nanoparticales with a higher specific surface area than that of the sol–gel synthesized oxide. The average sizes of tin oxide nanoparticles were found to be about 30 nm and 15 nm for the particles obtained by sol–gel and sonochemical methods, respectively. The surface area of SnO2 nanopowder obtained by the sol–gel method (calcined at 500 °C) was estimated to be 11.6 m2 g−1, and the mean pore diameter was found to be 6.33 nm. Whereas the mixed SnO/SnO2 sample (calcined at 500 °C) obtained by the sonochemical method exhibited a higher surface area of 43.11 m2 g−1 and an average pore diameter of 1.90 nm. The band gap of the synthesized tin oxides was estimated from the UV-vis. results to be 4.01 and 4.25 eV for the sol–gel and sonochemically synthesized samples, respectively.

Sonochemical Synthesis of Nanostructured ZnO/Ag Composites in an Ionic Liquid

Abstract In the present paper we show that nanocrystalline ZnO/Ag composites can be obtained via an ultrasonic-assisted approach in the ionic liquid 1-ethyl-3-methylimidazolium trifluoromethylsulfonate. Different techniques including, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and ultraviolet-visible spectroscopy (UV-vis) were utilized to characterize the synthesized materials. The XRD results revealed the formation of ZnO wurtzite structure along with metallic Ag in the ZnO/Ag composite. The particle size was estimated from the XRD results to be about 35 nm. The UV spectrum of ZnO/Ag showed the characteristic absorption band of wurtzite crystal structure of ZnO, and the presence of Ag in the ZnO/Ag composite led to a slight red shift. The employed ionic liquid acts as a template leading to the formation of nanoparticles of ZnO and of ZnO/Ag.