Zinc sulfide is a II–VI semiconductor with a wide band gap and strong photoluminescent properties that are highly size-dependent at the nanoscale. ZnS nanoparticles exhibit tunable optical emission, high exciton binding energy, and good chemical stability. They are widely used in optoelectronic devices, phosphors, LEDs, photocatalysis, and bioimaging applications, as well as in sensors due to their sensitivity to light and surface adsorption.