Cu-doping and annealing effect on the optical properties and enhanced photocatalytic activity of ZnO nanoparticles

Hexagonal wurtzite structure of Cu-doped ZnO nanoparticles with an optical band-gap of ∼3.48 eV has been synthesized through a co-precipitation method at room temperature followed by annealing at 600 °C for 3 h. Structural, morphological and optical studies are performed for different concentrations of Cu-doped ZnO and annealed ZnO nanoparticles. Crystallite size, lattice parameters, unit cell volume, bond length and Young's modulus are calculated and compared. Morphology and average particle size of the samples have been characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The favorable band-gap reduction and defect states for photocatalytic activity are demonstrated from UV-Visible absorption spectroscopy and room temperature photoluminescence (PL) spectroscopy data. The photocatalytic degradation efficiency of the prepared nanoparticles towards the toxic methylene blue (MB) dye has been successfully investigated under white light irradiation.