Enhanced Structural, Optical and Magnetic Properties of Cobalt-Doped Zinc Oxide Nanoparticles Synthesized via Co-Precipitation Method

Abstract

This study reported the synthesis and characterization of cobalt-doped zinc oxide (Co-ZnO) nanoparticles using the co-precipitation method with a focus on their structural, optical and magnetic properties. Pure ZnO and Co-ZnO nanoparticles were synthesized and compared to evaluate the effects of cobalt doping. X-ray diffraction (XRD) analysis revealed that cobalt doping led to a reduction in peak intensities and an increase in lattice strain, indicating successful substitution of Co2+ ions into the ZnO lattice. The average particle size of Co-ZnO nanoparticles decreased from 9.41 nm to 3.82 nm, with a corresponding increase in specific surface area from 1.17 × 1014 m2/g for pure ZnO to 1.65 × 1014 m2/g for Co-ZnO. UV-visible spectroscopy showed a blue shift in the absorption edge for Co-ZnO nanoparticles, with an energy band gap of 3.36 eV compared to 3.25 eV for pure ZnO exhibiting enhanced UV absorption capabilities. Photoluminescence (PL) spectra highlighted the presence of violet-blue and blue-green emissions, suggesting improved photocatalytic properties due to Co doping. Transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX) confirmed the hexagonal shape and successful incorporation of cobalt ion into the ZnO lattice. Vibrating-sample magnetometry (VSM) measurements revealed a significant increase in magnetization for Co-ZnO nanoparticles demonstrating enhanced ferromagnetic properties with a magnetic moment of 0.5198 T. This study concludes that cobalt doping significantly enhances the structural, optical, magnetic and photocatalytic properties of ZnO nanoparticles, making them suitable for applications in photocatalysis, gas sensing and spintronics.