Flower-like cuprous oxide: hydrothermal synthesis, optical, and electrochemical properties

Flower-like nanocrystalline (Cu2O) was prepared via a hydrothermal process using paraphenylenediamine which acts as a reducing and structure-directing agent. The morphology, the structure, the crystallinity, and the composition were studied through X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. It was found that the hydrothermal reaction time had a little effect on the morphology of Cu2O nanocrystals, but influenced the nanocrystal dispersibility. The optical properties of the as-synthesized Cu2O nanomaterials were studied by UV-visible diffuse reflection spectra and room temperature photoluminescence. The values of the band gap for Cu2O nanorods and nanoflowers were found to be 2.43 and 2.34 eV, respectively. A cyclic voltammetric study of the Cu2O nanoflowers revealed a reversible redox behavior with charge-discharge cycling corresponding to the reversible lithium intercalation/deintercalation process in the crystal lattice. Thus, Cu2O is a promising candidate for many applications such as an electrode material for a lithium ion battery.