Pure CoS and Different Concentrations of Fe/Nd Co-Doped CoS Nanoparticles: Photoluminescence and Photocatalytic Studies

This research utilized the co-precipitation method to produce pure CoS, and Fe/Nd co-doped CoS nanoparticle with different concentrations at room temperature. The samples were characterized using UV-visible spectroscopy, FT-IR, SEM, and XRD. XRD pattern showed a cubic structure, and the Debye-Scherrer technique revealed an average particle size of 8 nm and 13 nm for 3 at.% and 5 at.% of Fe/Nd co-doped CoS. FT-IR spectroscopy identified the functional groups present and chemical bonding and the adsorption of H2O molecules in the samples. In the prepared samples, SEM investigations revealed aggregation and the emergence of irregular forms. The excitation spectra set at 300-500 nm range with 2 of 300 nm detected two broad peaks at 350 and 400 nm and a sharp peak at 470 nm. On the other hand, the emission spectrum recorded in the 400-650 nm range with 2 of 400 nm showed broad emission peaks at 420 nm, 450 nm, and 480 nm. Tauc's plot revealed that the optical bad-gap of pure and co-doped CoS nanoparticles ranged from 3.19 eV to 3.81 eV, suitable for photocatalytic activity. The testing revealed that the photocatalytic degradation of methyl red dye proved to be significantly more efficient in alkaline mediums, demonstrating clear pH dependence. Furthermore, the kinetic study for the degradation of the samples yielded R2 values of 0.976, 0.996, and 0.991, indicating that the process followed first-order kinetics.