Green synthesis of hexagonal 2H-molybdenum disulfide (2H-MoS 2 nanostructures: Exploring the link between phytochemical composition, quantum confinement, and gram-selective antibacterial activity

Molybdenum disulfide (MoS2) nanostructures have antimicrobial potential, but sustainable synthesis methods and quantitative structure-property correlations are lacking. We synthesized 2H-MoS using aqueous extracts of Eruca sativa, Corchorus olitorius, and garlic as green reducing, stabilizing, and bio-sulfur agents. The products were characterized by XRD, SEM, TEM, HPLC, UV- Vis, zeta potential, TGA, and antibacterial testing against four bacterial strains (two Gram-positive, two Gram-negative). Crystallite sizes ranged from 6.9 nm (garlic) to 11.5 nm (arugula). Optical band gaps of 2.9-3.1 eV confirmed quantum confinement compared to bulk MoS2 (1.2-1.8 eV). Antibacterial testing revealed moderate inhibition zones (10-20 mm) exclusively against Gram-positive bacteria. Surprisingly, garlic-derived MoS2 showed the smallest crystallites and highest surface area but the weakest antibacterial activity due to a dense organic coating that blocks active edge sites. TEM revealed distinct morphologies: arugula produced nanosheet-like clusters, Jew’s mallow formed dense particle agglomerates, and garlic yielded ordered nanospheres (48-58 nm) with regular pore networks (≈30 nm). This work provides the first direct correlation between specific phytochemicals (allicin, quercetin, polysaccharides) and the resulting MoS2 structural, optical, thermal, and antibacterial properties.