Hierarchical growth of Cu2O double tower-tip-like nanostructures in water/oil microemulsion

A novel Cu2O hierarchical double tower-tip-like nanostructure has been successfully synthesized in water/oil (w/o) microemulsion. This kind of nanostructure is made of three-order structures. The primary structure is composed of three stems across and perpendicular to one another, like a hexapod-shaped structure. Four rows of nanorods epitaxially grown on each stem and perpendicular to the stem form the secondary structure. The tertiary structure is two rows of nanorods epitaxially grown on a secondary nanorod if the secondary nanorod is long enough. All the first-order, second-order, and third-order growth take place along orientations of < 001 >. The obtained samples are characterized by means of X-ray powder diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). It is found that the microemulsion system, water content, ligand, reaction temperature, reaction time, and concentration of NaOH play important roles in the formation of this novel morphology besides the crystal habit of Cu2O.