Enhancement in photo sensing and photocatalytic degradation activity of Cu doped ZnO nanoparticles prepared by co-precipitation method

In the present work, Copper (Cu) doped zinc oxide (ZnO) nanoparticles were prepared using a simple and cost-effective co-precipitation process. The objectives of the proposed work are to identify the cause of Cu dopant on the crystalline structure, morphology, optical characteristics of ZnO nanoparticles for photocatalytic as well as photosensing applications. X-ray diffraction (XRD) and Field emission scanning electron microscope (FESEM) examinations were used to identify the crystal structure and morphology of the prepared samples. The crystallite size of the undoped ZnO sample was 44 nm, which gets reduced to 36 nm with 5% Cu-doping. Using diffuse reflectance spectroscopy (DRS), the band gap of prepared samples of undoped to 5 wt% Cu doped ZnO was calculated, and it was found to be reduced from 3.31 to 3.26 eV. Photoluminescence (PL) spectra show a decrease in luminous intensity which is in line with the photocatalytic behavior. 5 wt% Cu doped ZnO sample displayed maximum degradation efficiency of 85% in 75 min and degradation rate of 0.02 min⁻¹. Additionally, photo-sensing studies of the 5 wt% Cu doped ZnO sample showed higher responsivity (R), detectivity (D*) and external quantum efficiency (EQE) values of 1.93 × 10⁻¹ AW⁻¹, 1.09 × 10¹¹ Jones and 45% respectively. The rise and fall time of 5 wt% Cu doped ZnO photodetector is in the order of 0.3 and 0.5 s.