Morphologies and microstructures of nano-sized Cu₂O particles using a cetyltrimethylammonium template

Hollow polyhedra and cubes of nanostructured Cu₂O particles have been synthesized by reduction of CuSO₄ with ascorbate acid in the solution phase. The nanostructures were obtained when the cetyltrimethylammonium (CTAB) concentration ranged from 0 to 0.03 M in the presence of NaOH. Structural characterizations, by means of x-ray photoelectron spectroscopy (XPS) for measuring Cu valence states and by electron microscopy for microstructure and chemical analyses, suggest that most Cu₂O nanoparticles are covered with a thin CuO shell arising possibly from reaction of the adsorbed oxygen on the Cu₂O particle surface. The blue shift is observed as microstructures of Cu₂O nanoparticles changed from cubic to hollow in ultraviolet and visible (UV-visible) absorption spectra. Both the Cu ₂O hollow and cubic nanostructures show certain quantum-confined effects. A cationic CTAB template mechanism is proposed to interpret the formation of the Cu₂O nanoparticles.