Solution-phase synthesis of single-crystal hollow Cu2O spheres with nanoholes

A wealth of superfine single-crystal hollow cuprous oxide (Cu2O) spheres with nanoholes have been prepared for the first time with glucose as the reducing agent and gelatin as a soft template. The mechanism of the formation of these hollow crystals with nanoholes has been studied, and the UV-visible absorption spectrum has been used to resolve the excitonic or interband transitions of the hollow Cu2O spheres. The band gap of the products calculated from the UV-vis spectra is as large as 2.67 eV, which is ascribed to the decrease of the overall crystal size and the hollowing of the Cu2O spheres with nanoholes.