Surface-modified CuO layer in size-stabilized single-phase CuO nanoparticles

Activated reactive evaporation has been used to grow copper oxide nanoparticles in the size range of 8-100 nm. X-ray diffraction spectra clearly show the presence of a single CuO phase. Detailed x-ray photoelectron spectroscopy studies show an increase in the ionicity of the CuO system with decreasing particle size. Depth profiling and finger printing of x-ray photoelectron spectra reveal that the CuO nanoparticles are capped with a CuO surface layer of thickness ≈1.6 nm. This study strongly suggests that the stabilization of the cubic CuO nanophase is enhanced by the formation of a CuO surface layer. © 2001 American Institute of Physics.