In situ decoration of Ag nanoparticles on hierarchical TiO2 nanowire nanofibers with enhanced catalytic activity used for the removal of 4-nitrophenol

Hierarchical materials are of great interest toward the development of catalysts because of their unique structures and large specific surface area. In this study, Ag-decorated TiO 2 (TiO 2 @Ag) nanowire nanofibers (NW NFs) were synthesized via the in situ decoration of Ag nanoparticles (NPs) on hierarchical TiO 2 NW NFs and their microstructure and catalytic activity for the removal of 4-nitrophenol were evaluated. TiO 2 NW NFs were first synthesized via the hydrothermal reaction of the electrospun TiO 2 NFs in a concentrated NaOH solution and then hydrothermally treated in a AgNO 3 solution to form the TiO 2 @Ag NW NFs. SEM observations showed that the TiO 2 @Ag NW NFs were assembled from numerous TiO 2 NWs subunits and exhibited a hierarchical and fibrous morphology with diameters in the range of 1–2 μm and lengths of tens of micrometers. TEM observations showed that many Ag NPs with diameters in the range of 4–10 nm were well grown on each TiO 2 NW with diameters of 20–40 nm. It was found that the TiO 2 @Ag NW NFs showed catalytic activity for the removal of 4-nitrophenol (4-NP), a representative contaminant. The catalytic removal efficiency of 4-NP by the TiO 2 @Ag NW NFs in the presence of visible light irradiation (0.639 min −1 ) was 3.2-fold higher than that in the absence of light irradiation (0.199 min −1 ), indicating that the TiO 2 @Ag NW NFs exhibit visible light-enhanced catalytic activity.