We report several wet-chemical methods for synthesis of one-dimensional CuO nanostructures in water-ethanol mixed solvents at 77-82 °C and 1 atm. Single-crystalline monodispersed CuO nanorods with a selected breadth in the range of 5-15 nm have been prepared by controlling reagent concentrations. The nanorods are preferentially grown along 〈010〉 directions. A two-step continuous process has also been developed to prepare CuO nanorods and ribbons (length up to 1 µm) with a large aspect ratio under pseudo-steady-state operation. Furthermore, a two-dimensional netted structure has been assembled for the first time from short nanorods formed after prolonged aging; the nanorods are attached each other using their {001}, {100}, and {110} crystal planes. With concentrated NaOH used in synthesis, the nanorods can also be extended along 〈100〉, which gives rise to the formation of CuO nanoplatelets. Various synthetic parameters have also been investigated.

A full range of novel multipod frameworks of Cu2O microcrystals has been prepared in solution phase via manipulating synthetic parameters. More importantly, a new organization scheme for three-dimensional crystal aggregates has been elucidated in this work; faceted microcrystal subunits (6, 8, and 12 pieces) with simple cubic or face-centered cubic lattices have been organized with space instruction of the formed frameworks. This organization scheme can be divided into two discrete steps:  (i) fractal growth of multipod framework from a nucleation center (i.e., space-definition), and (ii) attachment of crystal subunits according to the space locations assigned in (i). The microcrystal stacks also provide a base for creation of intracrystal porosity and crystal self-amplification. A remarkable correlation among the various crystal morphologies of Cu2O to their respective multipod frameworks has been revealed for the first time.