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.