Template-free hydrothermal synthesis of CuO/Cu₂O composite hollow microspheres

CuO/Cu2O composite hollow microspheres with controlled diameter and composition were prepared without the addition of templates and additives by hydrothermal synthesis using Cu(CH3COO)(2)center dot H2O as a precursor. Increasing the precursor concentration from 0.02 to 0.2 M increased the diameter of the composite hollow microspheres from 500 nm to 5 mu m. Moreover, the content of Cu2O in the composite hollow microspheres increased with increasing the reaction time or/and precursor concentration to produce a range of composite hollow microspheres with Cu2O contents from 20 to 80 wt %. A localized Ostwald ripening mechanism was proposed to account for the formation of CuO/Cu2O composite hollow microspheres. The photocatalytic activity experiment indicated that the prepared CuO/Cu2O composite hollow microspheres exhibited a higher photocatalytic activity for the photocatalytic decolorization of methyl orange aqueous solution under the visible-light illumination than the single phase CuO or Cu2O samples.