Hydrothermal synthesis of sheaf-like CuO via ionic liquids

Sheaf-like CuO consisting of nanoplatelets were synthesized by a hydrothermal method at 100 °C from Cu(NO₃)₂·3H₂O and NaOH in the presence of an ionic liquid 1-butyl-3-methyl imidazolium tetrafluoroborate ([BMIM]BF₄). The XRD indicated the high crystal quality of CuO with monoclinic crystal structure. FESEM and TEM images showed the nanoplatelets with lengths of 4-5 μm, thickness of 65-80 nm and end angle of 60°. FTIR spectra and TG/DSC curves confirmed the adsorption of [BMIM]BF₄ on the surface of CuO. The morphology of CuO could be controlled by the feeding manner of [BMIM]BF₄. It was demonstrated that [BMIM]BF₄ served as a cosolvent and modifiers in the reaction system. Further, the possible growth mechanism of the sheaf-like CuO was proposed.