Microemulsion Synthesis of Copper Oxide Nanorod-Like Structures

Abstract

Copper oxide (CuO) nanorod-like structures made of spherical nanocrystals were synthesized at moderate temperature (80°C) starting from CuCl₂·2H₂O crystals in a water/n-heptane microemulsion stabilised by the nonionic Brij-30 surfactant. Whole Powder Pattern Modelling of the X-ray diffraction pattern shows absence of linear and planar defects with crystalline domains in the range of 4–8 nm. A linear correlation between the average size of the particles and the quantity of water in the system was observed: all synthesised specimens show a large blue shift of the energy bandgap (up to 2.7 eV versus 1.2 eV of bulk CuO) resulting from quantum confinement effects. The mechanism of growth of the spherical nanoparticles into nanorod-like structures has been elucidated.

Keywords:

• CuO
• electron microscopy
• grain growth
• microemulsion
• nanostructured materials
• X-ray diffraction

Acknowledgments

We acknowledge Prof. Stefano Giannella, Dr. Valeria Tagliazucca and Mr. Enrico Moser for assistance in TEM and spectroscopy investigations