A convenient method for preparing shape-controlled nanocrystalline Cu2O in a polyol or water/polyol system

A facile method capable of preparing well-dispersed Cu₂O nanocrystals with controllable shapes, such as rods, needles to other irregular shapes, has been developed. The different shapes of Cu₂O nanocrystals can be obtained simply by adjusting the composition of the reaction system. For example, if small amounts of poly(vinyl pyrrolidone) (PVP) was added in a mixture of Cu(NO₃)₂ and ethylene glycol, the needle-shaped nanocrystals could be formed. Interestingly further addition of small amounts of water in above system enabled us to obtain Cu₂O nanorods. Moreover the ratio of water/EG and the species of stabilizers played a crucial role in fine tuning the structure and size of as-prepared Cu₂O nanocrystals.