One-dimensional BiOBr nanosheets/TiO2 nanofibers composite: Controllable synthesis and enhanced visible photocatalytic activity

Abstract This work featured the synthesis and characterization of one-dimensional BiOBr nanosheets/TiO 2 nanofibers composite (BiOBr/TiO 2 NFs). The anatase TiO 2 nanofibers (TiO 2 NFs) were obtained via electrospinning and calcination at 520 °C. BiOBr nanosheets were subsequently grown onto TiO 2 NFs via solvothermal route. BiOBr loading on the surface of TiO 2 NFs could be adjusted by controlling Bi and Br concentrations during the solvothermal process. The BiOBr/TiO 2 NFs composite with high loading of BiOBr, denoted as BiOBr/TiO 2 NFs-2 (S2), displayed the highest photocatalytic activity for the degradation of 4-Nitrophenol (4-NP) in water ( i.e., complete degradation in 180 min) relative to the BiOBr/TiO 2 NFs with lower BiOBr loading (BiOBr/TiO 2 NFs-1 (S1)), the mixture of TiO 2 NFs and BiOBr, TiO 2 NFs, and BiOBr. Such enhancement in photocatalytic activity was attributed to the extended absorption in the visible light region from the narrow band-gap of BiOBr and the more effective photogenerated electron-hole separation via the BiOBr-TiO 2 NFs heterojunction. We used complementary powder XRD, UV–vis, SEM, TEM, and XPS data to propose the photocatalytic mechanism of S2 and discuss the structures of S2, S1, BiOBr powder, and TiO 2 NFs in relation to their photocatalytic activities. The best photocatalyst, i.e., S2 additionally retained high photocatalytic activity over the consecutive 6 (re-use) cycles, which highlighted its practical applicability for large scale wastewater treatment.