GREEN AND CONVENTIONAL SYNTHESIS OF NiO NANOPARTICLES: IMPACT OF ERUCA SATIVA ON PHOTOCATALYSIS

In this study, we report a hybrid synthesis route to nickel oxide (NiO) nanoparticles that combines conventional sol–gel and Pechini methods with a green, bio-mediated approach using Eruca sativa (rocket) extract for the first time in NiO synthesis. This plant-based approach offers a genuinely sustainable alternative to purely chemical synthesis, while a factorial design helps us identify the specific contributions of each component. Four distinct samples were prepared from nickel acetate and calcined at 450 °C for two hours, then characterized by XRD, FTIR and UV–Vis spectroscopy to probe their structure and optical properties; their photocatalytic ability was evaluated by degrading methylene blue under UV light. Interestingly, the Pechini route produced markedly larger crystallites (41.3 nm) than the sol–gel co-precipitation method (15.5 nm), pointing to the decisive role of citric acid and ethylene glycol in steering crystal growth. More strikingly, incorporating rocket extract significantly narrowed the optical band gap – from 3.46 eV down to 3.22 eV in Pechini samples, and from 3.52 eV to 3.31 eV in the sol–gel batch. The best-performing catalyst was the bio-assisted Pechini sample, which degraded 65.6 % of the dye in 180 min, a clear improvement over the 43 % achieved by its conventional counterpart. Our findings suggest that blending optimized chemical routes with botanical extracts is a viable, powerful strategy for engineering high-efficiency NiO photocatalysts suited to sustainable water treatment.