Structural, optical, magnetic and antibacterial study of pure and cobalt doped ZnO nanoparticles

In this research paper, pure and Co-doped ZnO nanoparticles were synthesized by using the wet precipitation method. The structural, morphological, optical and magnetic properties of the pure and Co doped ZnO nanoparticles were investigated. X-ray diffraction (XRD) spectra of Co doped ZnO NPs shows the shifting of characteristic XRD peak toward the higher angle which revealed that dopant Co is successfully incorporated into the lattice structure of ZnO nanoparticles. Structural morphology of pure and Co-doped ZnO nanoparticles samples was ascertained by using the scanning electron microscopy which confirms the formation of fine and clear spherical nanocrystallites with clear and distinctive boundaries. Energy-dispersive X-ray spectroscopy spectra show the elemental composition of Co²⁺ ions effectively in lattice site of Zn²⁺ ions. Photoluminescence and Raman spectra indicate the presence of oxygen vacancies and donor defects in the doped samples. UV–visible absorption spectroscopy showed the blue shifting of absorption edge as compared to pure ZnO nanoparticles sample. Pure and Co-doped ZnO nanoparticles revealed considerable changes in the M–H loop, particularly the diamagnetic behavior changed into ferromagnetic for Co-doped samples in vibrating sample magnetometer investigation. In this study, the antibacterial properties of the cobalt doped zinc oxide were further studied against three Gram-negative pathogens via using agar well diffusion technique. Co doped nanoparticles samples were then investigated as antibacterial agent to control the bacterial growth. It is further confirmed from our study that Co-doped ZnO NPs and their exposure to sunlight enhanced the antibacterial activity against three bacterial pathogens under study.