Plant‐assisted synthesis of Fe3O4 nanoparticles for catalytic degradation of methyl orange dye and electrochemical sensing of nitrite.

The present study details a more environmentally friendly method for synthesizing iron oxide nanoparticles (Fe3O4‐NPs) utilizing Hibiscus sabdariffa (H. sabdariffa) leaf extract. The produced H. sabdariffa/Fe3O4‐NPs underwent characterization through VSM, XRD, FESEM‐EDX, TEM and FTIR analyses. The FESEM and TEM images revealed that the H. sabdariffa/Fe3O4‐NPs had a narrow distribution and an average particle size of 5±2 nm. Catalytic degradation studies of the synthesized Fe3O4‐NPs exhibited efficient reduction of methyl orange (MO) dye. The degradation of MO catalysed by H. sabdariffa/Fe3O4‐NPs follow the pseudo‐first order kinetics, with a rate constant of 0.0328 s−1 (R2=0.9866). Moreover, in electrochemical sensing studies, the anodic peak current of nitrite (NO2−) for H. sabdariffa/Fe3O4‐NPs/GCE showed a linear relationship with its concentration within the range of 0.5–7.5 mM, achieving a detection limit of 0.29 μM. These findings demonstrate that the modified electrode with Fe3O4‐NPs synthesized using H. sabdariffa leaf extract serve as a novel electrochemical sensor for determining NO2− with high sensitivity and reproducibility. [ABSTRACT FROM AUTHOR]