Optimization of Cobalt Doping Content for the Synthesis of High-performance Photocatalytic Co-ZnO Nanoparticles

Cobalt (Co)-doped Zinc Oxide (ZnO) nanoparticles were synthesized via a Sol-gel method, without post-synthesis thermal treatment, for potential application in photocatalytic degradation of organic pollutants in aqueous environments. The influence of varied Co-content concentrations (ranging from 0 to 10%) on the structural characteristics and photocatalytic efficiency of the Co-doped ZnO nanoparticles was systematically investigated. Spectroscopic analysis utilizing UV-Visible spectrophotometry revealed that variations in cobalt doping concentrations exhibited minor impact on the bandgap energies. X-ray diffraction analysis and scanning electron microscopy (SEM) confirmed the successful formation of hexagonal wurtzite structure and morphology in both pure and Co-doped ZnO samples. The photocatalytic performance of the synthesized nanoparticles was evaluated through the photodegradation of methylene blue as a model organic pollutant under UV-Visible LED illumination. Optimal photocatalytic performance was achieved with 3% cobalt doping concentration, demonstrating a remarkable degradation efficiency of 94.99% after 40 min of irradiation.