Chemical and green synthesized Co/Ni-doped hematite nanoparticles for enhancing the photocatalytic and antioxidant properties

This research focuses on developing environmentally friendly and economically viable Co/Ni-doped hematite nanoparticles (HNPs) through both chemical and green synthesis methods and evaluated their potential for biomedical and environmental applications. The chemical synthesis employs polyvinylpyrrolidone (PVP), while the green approach utilizes Azadirachta indica (A. indica) leaf extract as a stabilizing agent. Co/Ni-doped HNPs are crystalline size ranging from 14 to 21 nm, morphology analysis revealed that the NPs exhibited a quasi-spherical, with an average particle size ranging from 15.98 to 25.91 nm, and dopants confirmed to contain by the XPS spectra. VSM study explains magnetic parameters, coactivity, residual magnetism, and magnetization. A. indica plants contain quinones, saponins, glycosides, alkaloids, and flavonoids. Characterization of the nanoparticles reveals optimized Co/Ni-doped HNPs with enhanced photocatalytic activity. These nanoparticles exhibit a remarkable 93%-95% degradation of UV-reactive dyes (methyl orange and methylene blue) within 90 min, attributed to structural and surface modifications that improve light absorption and enhance charge separation. The study concludes that green-synthesized Co/Ni-doped HNPs outperform chemically synthesized counterparts as superior photocatalysts. Additionally, antioxidant evaluations using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and nitric oxide (NO) assays suggest significant antioxidant capabilities. A high scavenging activity percentage, ranging from 83% to 88%, was observed, which increased with higher concentrations of the synthesized Co/Ni-doped HNPs making these nanoparticles suitable for biomedical and environmental applications that require a magnetic system. In this study, the IC50 values for the antioxidant activity of chemically and green synthesized Co/Ni-doped hematite nanoparticles against the DPPH/NO assay were calculated to be 18.33 mu g ml-1 and 16.09 mu g ml-1, respectively. The research highlights the multifunctional properties of Co/Ni-doped HNPs, addressing the demand for tailored inorganic magnetic nanoparticles with minimal ecological impact.