Influence of copper doping on structural, morphological, optical, and vibrational properties of ZnO nanoparticles synthesized by sol gel method

Cu-doped ZnO nanocrystals (with 0, 0.5, 1.0, 1.5, and 2.0 at.% Cu) have been successfully synthesized by a sol-gel method. The influence of Cu content on the properties of ZnO nanoparticles have been studied by various characterization techniques. XRD analysis reveals the formation of hexagonal wurtzite structure in all samples, confirming the incorporation of Cu ions into the ZnO lattice. The crystallite size and unit cell volume are modified with the Cu content. Morphology characterization by SEM and HRTEM revealed that Cu-doped samples consist of mixture of nanoparticles and nanowires. The energy band gap of the samples was red shift due to Cu incorporation in the ZnO lattice. The PL emission intensity of the Cu-doped samples decreases with increasing Cu content. Vibrational spectroscopy confirms metal oxide bond formation and reveals stress present in the samples. Under visible light illumination, the photocatalytic performance of all samples was studied by using methylene blue as a model molecule.