Synthesis of Ultrasmall Cu2 O Nanocubes and Octahedra with Tunable Sizes for Facet-Dependent Optical Property Examination.

Size-tunable small to ultrasmall Cu2 O nanocubes and octahedra are synthesized in aqueous solution without the introduction of any surfactant. These nanocrystals provide strong evidence of the existence of facet-dependent optical absorption properties of Cu2 O nanoparticles, showing nanocubes always have a more redshifted absorption band than that of octahedra having a similar volume by about 15 nm.