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Ultrasound-assisted synthesis of mesoporous β-Ni(OH)2 and NiO nano-sheets using ionic liquids
Journal of Materials Chemistry (2012)
  • Tarek Alammar
  • Osama Shekhah
  • Jonas Wohlgemuth
  • Anja V. Mudring

Via a facile ultrasound synthesis from nickel acetate and sodium hydroxide with ionic liquids as the solvent and template it is possible to obtain nano-β-Ni(OH)2 of various dimensionalities depending on the reaction conditions with the ionic liquid (IL) being the most important factor. Scanning electron microscopy (SEM) imaging showed β-Ni(OH)2 to form as nanosheets, nanorods and nanospheres depending on the IL. ILs with strong to moderate hydrogen bonding capability like [C3mimOH][Tf2N] (1-(3-hydroxypropyl)-3-methylimidazolium bis(trifluoromethanesulfonylamide)), [C4mim][Tf2N] (1-butyl-3-methylimidazolium bis(trifluoromethanesulfonylamide)) and [Edimim][Tf2N] (1-ethyl-2,3-diemethylimidazolium bis(trifluoromethanesulfonylamide)) lead to the formation of nanosheets whilst [Py4][Tf2N] (butyl-pyridinium bis(trifluoromethanesulfonylamide)) leads to nanoparticles and [N1888][Tf2N] (methyltrioctylammonium bis(trifluoromethanesulfonylamide)) to nanorods. Subsequent calcination of the materials at elevated temperatures (285–425 °C) leads to the conversion of β-Ni(OH)2 to NiO under preservation of the nanostructure. Scanning electron microscopy (SEM), X-ray diffraction (XRD), TG-DTA, X-ray photoelectron spectroscopy (XPS), and energy dispersive X-ray spectroscopy (EDX) were used to observe the morphology, crystallinity, and chemical composition in more detail. Mesoporous NiO nanosheets obtained in [C4mim][Tf2N] possess an exceptionally high surface area of 141.28 m2 g−1 and a pore volume of 0.2 cm3 g−1 at 285 °C. As a result of calcination at 425 °C the surface area decreased to 92.84 m2 g−1, but the pore volume increased to 0.48 cm3 g−1. In addition, the product has an extraordinarily high saturation magnetization of 1.38 emu g−1, a coercivity of 117 Oe and an excellent specific capacitance of 199.4 F g−1 which renders the material highly interesting for application in supercapacitors.

Publication Date
Publisher Statement
Copyright 2012 Royal Society of Chemistry
Citation Information
Tarek Alammar, Osama Shekhah, Jonas Wohlgemuth and Anja V. Mudring. "Ultrasound-assisted synthesis of mesoporous β-Ni(OH)2 and NiO nano-sheets using ionic liquids" Journal of Materials Chemistry Vol. 22 (2012)
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