Facile hydrothermal synthesis and characterization of novel Co-doped ZnS nanoparticles with superior physical properties

This study utilized simple hydrothermal conditions for developing novel Co(x)Zn(1-x)S nanosphere particles with varying Co doping ratios (0.0 <= x < 0.09). We analyzed the samples for structural, morphological, and optical parameters, taking special care to correlate all these aspects. The structural analysis by x-ray diffraction (XRD) reveals that both pure ZnS nanoparticles and Co(x)Zn(1-x)S nanospheres possess crystalline and cubic-phase purity. The Williamson-Hall method employed XRD line profile analysis to evaluate the microstructural characteristics of the nanoparticles. The crystallite size in the doped samples varied from 5.8 nm to 8 nm, contingent upon the cobalt concentration in the zinc sulfide lattice. The field emission scanning electron microscopy analysis verified that the obtained nanoparticles had a uniform spherical morphology and narrow size distribution. UV-Vis spectroscopy indicates that the optical energy gap of Co(x)Zn(1-x)S nanospheres ranges from 4.74 eV to 5.1 eV within the ultraviolet-visible spectrum. The infrared spectra exhibit the three distinct Zn-S stretching vibrational modes within the wavenumber range of 470 cm(-1) to 706 cm(-1). X-ray photoelectron spectroscopy (XPS) analysis revealed that all samples exhibited a Zn2+ oxidation state within the crystal lattice and contained sulfur vacancies. The XPS test verifies the presence of both Co3+ and Co2+ oxidation states inside the lattice structure of ZnS nanoparticles. This can be advantageous in specific applications. The results of this study suggest that Co(x)Zn(1-x)S nanospheres has potential functional applications across various domains.