The effect of Nigella sativa seed extract concentration on crystal structure, band gap and antibacterial activity of ZnS-NPs prepared by green route

The present article investigates the effect of Nigella sativa seed extract concentration on crystal structure, band gap, and antibacterial activity of ZnS-NPs prepared by the green route. The study used a facile and eco-friendly method to obtain zinc sulfide nanoparticles (ZnS-NPs) using Nigella sativa seed (NSS) extract as a capping agent. XRD, SEM, FTIR, and UV-vis spectroscopy were employed to study the properties. The samples were also evaluated for antibacterial activity, and the obtained result shows pure crystalline ZnS-NPs with a cubic structure as being affirmed via powder XRD. FTIR spectra assert the existence of NSS extract as a capping agent. The SEM images of the obtained nanoparticles revealed that the prepared powders were composed of a mixture of fine and large grains of the product particles. The optical band gap computed from Tauc's plot is found to decrease from 3.37 to 3.11 eV (Red shift). The antibacterial activity of ZnS-NPs was assessed on selected Gram-positive and Gram-negative bacteria strains (S. aureus and E. coli, respectively). The inhibition zones of ZnS-NPs were 26 and 19 mm for S. aureus and E. coli, respectively. The improved optical and antibacterial properties of ZnS-NPs make them suitable for optoelectronic applications and antibiotic development.