Cupric oxide nanoflowers synthesized with a simple solution route and their field emission

Assemblies of flower-like cupric oxide nanostructures (CuO nanoflowers) were synthesized directly on Cu plates in KOH solution at room temperature. These nanoflowers are believed to have been the result of processes such as oxidation, complex formation, condensation, Ostwald ripening and dissolution. Each nanoflower contained a very large number of nanometer-scaled flakes (petals) and each petal further branched into tips at its end. The sharpness of these tips resulted in a sufficiently high field enhancement factor. Field emission was available from the CuO nanoflowers and the turn-on field was about 8.5 V/μm. Compared with other methods for fabricating CuO field emitter, this solution route featured remarkable simplicity and cheapness.