Synthesized NiO Nanostructures via Sol–Gel: Unveiling the Role of Annealing Conditions on Structural and Antioxidant Properties

NiO octahedral nanoparticles were synthesized via the sol–gel method and subsequently characterized using XRD, SEM, and FTIR techniques. By XRD analysis of our results the influence of annealing temperature and time duration on the structural and morphological nanoparticles investigated. The synthesized NiO nanostructures predominantly crystallized in a face-centered cubic (fcc) phase, except for the sample annealed at 300°C. From the XRD data lattice constant obtained. The analysis revealed that increasing the annealing temperature promoted nanoparticle growth. By extending annealing time duration, first crystallite size reduced, then it remained fixed at longer times. The antioxidant potential of the NiO nanoparticles was further assessed using the DPPH radical scavenging assay. Notably, the sample annealed at 400°C for 24 h exhibited significantly enhanced antioxidant activity (76.12 ± 3.43%) compared with the other conditions, highlighting the crucial role of thermal treatment in tailoring both the structural evolution and functional performance of NiO nanomaterials.