Ag-doped NiS nanocubes: Tailoring properties for optimal antibacterial performance

Abstract

This study explores the synthesis of silver-doped nickel sulfide nano-cubes (Ni1-xAgxS: x= 0.00, 0.04, and 0.08) through a cost-effective hydrothermal process. X-ray diffraction analysis assured the presence of hexagonal NiS nanoparticles with fine crystallinity, with an estimated crystallite size of Ag-doped NiS ranges from 21.19 to 15.69 nm. A reduction in crystallite size was observed while including Ag ions along with enhancement in lattice constants for ‘a’ and ‘b’ from 3.416 Å to 3.424 Å and ‘c’ from 5.280 to 5.286 Å. The scanning electron microscopic images displayed cubic shaped agglomerated particles, that seemed quite suitable for antibacterial activity. The materials exhibit semiconducting behavior, as evidenced by increased direct current electrical conductivity with the rise in temperature. With increased silver content, the direct current electrical conductivity rises, and activation energy decreases from 0.246 to 0.213 eV. Dielectric characteristics, including dielectric constant, dielectric loss, and AC electrical conductivity, show a positive correlation with temperature, and all the aforementioned values elevates with systematic variation in Ag doping. The Agar well-diffusion method evaluates the antibacterial activity of un-doped and Ag-doped NiS nano-cubes against various pathogens, such as Gram-positive bacteria (M. luteus and S. aureus) and Gram-negative bacteria (E. coli and S. enterica), and significant inhibitory zones against all tested microbes, confirming the potential antibacterial efficacy. The Ag-doped NiS exhibited enhanced antibacterial efficiency. This research highlights Ag-doped NiS nano-cubes attributed with multifaceted functionalities, making them promising candidates for particular usage such as targeted drug delivery systems, antibacterial powder, wastewater treatment and pharmaceutical applications.