A Rapid One-Pot Synthesis of CuO Rice-Like Nanostructure and Its Structural, Optical and Electrochemical Performance

Abstract

We report the production of high stable rice-like CuO nanostructures synthesized by a facile and one-step hydrothermal method using urea as a fuel agent. The thermogravimetric nature, phase purity, morphology, and structure of rice-like CuO nanostructures have been characterized by thermogravimetric–differential thermal analysis, powder x-ray diffraction (PXRD), field-emission scanning electron microscopy (FESEM), and energy dispersive x-ray spectroscopy. PXRD revealed the formation of monoclinic CuO with an average crystallite size of around 20 nm. FESEM showed a rice-like morphology with an average size of 40–50 and 100–120 nm along the shorter axis and longer axis, respectively. UV-DRS analysis confirmed a considerable blue-shift in the optical band gap (E⁻ = 1.45 eV) owing to a quantum confinement effect. X-ray photoelectron spectroscopy and electron paramagnetic resonance spectra confirmed the presence of copper in Cu²⁺ state. Furthermore, we can use these electrodes for their electrochemical supercapacitive properties, like cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectra. The nano-rice CuO showed an enhanced specific capacitance of 305 F/g at a current density of 1 A/g.