Quantum confinement effect in ZnO nanoparticles synthesized by co-precipitate method

Quantum mechanical effects such as an increased bandgap of semiconductors with reduction of size are viewed as having strong potential for future applications. In the present work, zinc oxide (ZnO) nanoparticles (NPs) were synthesized via the co-precipitate method. Very narrow particle size distribution of the ZnO nanoparticles was achieved through careful control of the synthesis conditions. The structural, morphological, and optical characterization was carried out using X-ray diffraction, atomic force microscopy, and UV–vis reflectance techniques, respectively. The results indicated that increasing the temperature from 60 to 65 °C caused a subsequent increase in particle size from ∼4 to 12 nm. An associated increase in bandgap with decrease in particle size was also noticed which is a strong indication of the quantum confinement effect.