Facile hydrothermal synthesis of the colloidal hierarchical Volborthite (Cu3V2O7(OH)2•2H2O) hollow sphere phosphors

Colloidal hierarchical self-assembled Cu3V2O7(OH)(2)center dot 2H(2)O hollow spheres were synthesized using a facile hydrothermal synthesis route without using PS hollow sphere template. Powder x-ray diffraction (XRD) of the obtained Cu3V2O7(OH)(2)center dot 2H(2)O sample demonstrated that the sample well-indexed to the monoclinic phase with high purity and well crystallinity. Fourier Transform infrared (FT-IR) of the sample proved hydrophilicity of the as-synthesized sample. Moreover, scanning electron microscopy (SEM) analysis indicated that the product consist of a large amount of the colloidal hierarchical Cu3V2O7(OH)(2)center dot 2H(2)O hollow spheres with a mean diameter of about 2-4 mu m, in which an individual self-assembled spherical structure was composed of a large number of the 50-90 nm nanoparticles. The optical properties of the sample was studied by ultraviolet-visible spectroscopy (UV-Vis) and emission/excitation spectra analyses (PL). The results showed that the sample has photo absorption ability in the visible region and an energy band-gap of 2.44 eV was estimated from UV-Vis absorption spectrum. Also, the as-prepared nanostructures has a very red-shifted PL emissions with high intensity under the excitation wavelength of 237 nm in their photoluminescence spectra.