Low-temperature synthesis of hetero-structures of magnetically separable iron oxide@Au-rGO nanocomposite for efficient degradation of organic dye under visible light irradiation.

In the present study, Fe ₃ O ₄ @Au core-shell nanoparticles decorated on reduce graphene oxide (Fe ₃ O ₄ @Au/rGO) nanocomposite were synthesized using the reduction method by sodium citrate, Hummer's method, and hydrothermal method, respectively. The as-prepared nanostructures were characterized by X-ray diffraction (XRD), Energy Dispersive X-ray (EDX), transmission electron microscopy (TEM), scanning electron microscopy (SEM)to assess the surface features, crystallinity and morphological characteristics. These nanostructures were employed for photocatalytic degradation of crystal violet (CV), and amongst them, Fe ₃ O ₄ @Au/rGO nanocomposite offered the best results under the visible light irradiation and optimal conditions. The effect of the amount of nano-photocatalyst, initial CV concentration, the initial pH, temperature, stirring speed, and degradation time was evaluated individually. A 100% degradation was obtained after 1 min in the presence of 0.008 g nano-photocatalyst, and also 100% of degradation was achieved after 5 min in the presence of 0.005 g of the prepared nano-photocatalyst. After a few tests, its photocatalytic performance was retained, implying the superior stability of Fe ₃ O ₄ @Au/rGO nanocomposite. The kinetic study of photocatalytic degradation also indicated that the fit model for the kinetic reaction was the pseudo-second-order kinetic model. Finally, the photocatalytic degradation of real samples with synthesized nanocomposite showed promising results.
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