Boosting visible light photocatalytic and antibacterial performance by decoration of silver on magnetic spindle-like bismuth ferrite

Visible light-activated Ag-doped spindle-like BiFeO3 (Ag-BFO) magnetic nanocomposite using different Ag loadings was synthesized via hydrothermal synthesis methods. The structural, morphological, optical and magnetic properties of as-prepared nanocomposite was analyzed by various characterization techniques. Field emission scanning electron microscopy images revealed the distribution of metallic Ag on the surface of spindlelike BFO with the widths ranging from 30 to 60 nm and the lengths from 200 to 250 nm. The X-ray photoelectron spectroscopy spectra showed that the electronic states of Bi3+, Fe3+ and Ag-0 existed in the Ag-BFO nanocomposite. UV-Vis diffuse reflectance spectra showed a red-shift on the light absorption edges after the loading of metallic Ag. Fourier transform infrared spectroscopy studies confirmed the presence of metallic Ag and Fe - O bond of FeO6 octahedral perovskite structure. The photocatalytic results presented that the Ag-BFO nanocomposite exhibited boosted visible light photoactivity on the degradation of malachite green (MG) dye. Especially, the 3 wt% Ag-BFO nanocomposite displayed excellent photoactivity than that of the pure BFO. The boosted photoactivity of Ag-BFO nanocomposite can be credited to the high electron-hole pairs separation efficiency and hydroxyl (center dot OH) radicals generation capability as witnessed by photoluminescence and terephthalic-photoluminescence (TA-PL) measurements. The Ag-BFO mineralization of MG dye under different light sources suggested that around 90.5% COD removal was achieved under sunlight irradiation, while 20.9% and 33.9% of COD were removed under visible and UV light irradiation, respectively. Other organic substances such as methylene blue, sunset yellow, phenol and 2,4-dichlorophenoxyacetic acid were also successfully degraded under the identical condition. Moreover, the Ag-BFO nanocomposite retained its photoactivity and morphological stability even after five recycling runs. The separation of Ag-BFO nanocomposite from the aqueous suspension was also relatively easy due to its strong ferromagnetism property. The radical scavengers study also showed that hole (h(+)), hydrogen peroxide (H2O2) and center dot OH radicals were the core active species for the Ag-BFO nanocomposite catalytic system. Furthermore, the Ag-BFO nanocomposite showed much improved antibacterial activities towards the Escherichia coll. and Micrococcus hams in comparison with the pure BFO. These findings presented that the Ag-BFO magnetic nanocomposite can be utilized as photocatalytic and antimicrobial agents for the prospective practical applications in the wastewater treatment.