Bioreductive deposition of highly dispersed Ag nanoparticles on carbon nanotubes with enhanced catalytic degradation for 4-nitrophenol assisted by Shewanella oneidensis MR-1.

Biogenetic nanomaterials research provides insights and valuable implications for the green synthesis of nanomaterials and auxiliary biodegradation behaviors. Ag nanoparticles (Ag NPs) fabricated on multiwalled carbon nanotubes (MWNTs) (Ag/MWNTs nanocomposites) are prepared in situ assisted by Shewanella oneidensis MR-1 (S. oneidensis MR-1) that provide respiratory pathway to transmit electrons. The Ag/MWNTs nanocomposites are characterized by a scanning electron microscopy (SEM), an energy dispersive X-ray (EDX), a transmission electron microscopy (TEM), an X-ray diffraction (XRD), and an X-ray photoelectron spectroscopy (XPS), respectively. The results indicate that Ag NPs (less than 20 nm in diameter) are successfully formed on the MWNTs without an aggregation. In application studies, the catalytic activities of the Ag/MWNTs nanocomposites towards the reduction of 4-nitrophenol (4-NP) by sodium borohydride (NaBH4) are tracked by a UV-visible spectroscopy. It is suggested that the Ag/MWNTs nanocomposites exhibit a satisfactory catalytic efficiency, which might be ascribed to the high dispersion of Ag NPs on MWNT surfaces. Moreover, the final results indicate that only after 10 min of reaction, the catalytic degradation ratio of 4-NP reaches 94.0% in the presence of Ag/MWNTs nanocomposites assisted by S. oneidensis MR-1.