Shape-controlled synthesis of single-crystalline cupric oxide by microwave heating using an ionic liquid

Cupric oxide (CuO) with leaf-like, chrysanthemum-like and rod shapes have been synthesized by microwave-assisted approach using an ionic liquid 1-n-butyl-3-methyl imidazolium tetrafluoroborate ([BMIM]BF4). By controlling the concentration of [BMIM]BF4 and reaction time, shape transformation of CuO nanostructures could be achieved in a short period of time. The crystal structure and morphology of products were characterized by XRD, TG, FESEM/EDS, and TEM/SAED. A possible mechanism for the shape transformation of CuO nanostructures was proposed. In addition, UV–vis spectra were employed to estimate the band gap energies of the nanosized semiconductors.