Enhancing Optical and Antioxidant Functionality in Zinc Doped Nickel Sulfide Nanoparticles

This study focuses on the optical and antioxidant properties of zinc-doped nickel sulfide (Zn–NiS) nanoparticles synthesized via an eco-friendly co-precipitation method, using varying zinc concentrations of 10%, 20% and 30%. In structural analyses using IR, SEM, TEM, and XRD techniques, Zn-NiS nanoparticles exhibited distinct features compared to undoped nickel sulfide (NiS), with EDAX confirming its crystalline organization. At higher Zn doping levels, optical studies based on Tauc equation revealed a redshift in the absorption edge and a reduction in band gap energy, attributed to defect-induced modifications in the electronic structure. Structural and morphological investigations confirmed phase stability (hexagonal) and demonstrated doping-dependent morphological transitions—from rod-like structures to porous clusters. Notably, 30% Zn-doped NiS exhibited approximately 95% inhibition at a concentration of 1000 µg/mL in DPPH radical scavenging assays, highlighting its remarkable antioxidant activity. These findings underscore the dual functional potential of Zn-NiS for sustainable technological applications, particularly in the biomedical field (as antioxidants) and in optoelectronics (via tunable band gaps).