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Biosynthesis of Ag2S/TiO2 nanotubes nanocomposites by Shewanella oneidensis MR-1 for the catalytic degradation of 4-nitrophenol

Yang, Mi, Shi, Xianyang
Environmental science and pollution research international 2019 v.26 no.12 pp. 12237-12246
Shewanella oneidensis, X-ray diffraction, X-ray photoelectron spectroscopy, biosynthesis, energy-dispersive X-ray analysis, light, nanocomposites, nanoparticles, nanotubes, p-nitrophenol, photocatalysis, sodium borohydride, titanium dioxide, transmission electron microscopy
Biosynthesized nanocomposites are attracting growing interests because they are environmentally friendly. Ag₂S nanoparticles (Ag₂S NPs) are deposited in situ on the surfaces of TiO₂ nanotubes (TNTs) via Shewanella oneidensis MR-1 to form Ag₂S/TNT nanocomposites. The prepared Ag₂S/TNTs nanocomposites are characterized using high-resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and energy-dispersive X-ray spectroscopy. The results show that Ag₂S NPs smaller than 8 nm are successfully synthesized and fabricated on the TNT surfaces with relatively uniform distribution. The catalytic performance of the Ag₂S/TNT nanocomposites is evaluated for catalytic reduction in the presence of NaBH₄ and the photocatalytic degradation of 4-nitrophenol (4-NP) under visible light. The Ag₂S/TNT nanocomposites show excellent catalytic activity and good stability in the 4-NP reduction process. The 4-NP degradation ratio reaches 98.3% in 50 min, and 87% conversion was achieved after eight cycles. The Ag₂S/TNT nanocomposites also exhibit excellent photocatalytic activity for 4-NP at a rate of 0.69 h⁻¹, and the complete degradation of 4-NP was observed within 5 h. Therefore, this study offers an environmentally friendly approach to synthesize nanocomposites for practical applications.