Multi-heterojunction of SnO2/Bi2O3/BiOI nanofibers: Facile fabrication with enhanced visible-light photocatalytic performance

One dimensional multi-heterojunction SnO2/Bi2O3/BiOI nanofibers were successfully fabricated by electrospinning and chemical etching method at room temperature. The BiOI nanosheets were uniformly immobilized on the surface of heterojunction nanofibers through I− ion etching process. The as-prepared samples were measured by X-ray diffraction (XRD), scanning electron microscope (SEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflection spectroscopy (DRS), photoluminescence (PL) and Brunauer-Emmett-Teller (BET) analysis. Comparing with Bi2O3, BiOI and SnO2/Bi2O3, the multi-heterojunction SnO2/Bi2O3/BiOI nanofibers exhibited higher photocatalytic activity for the removal of methyl orange (MO) and Cr (VI) ions under visible light irradiation. The photocatalytic activity of NFs-15 for the removal of MO and Cr (VI) ions increased by 3.15 and 6.38 times compared with SnO2/Bi2O3. Besides, the XRD spectra of NFs-15 before and after irradiation confirmed the cycling stability of the photocatalysts. A possible mechanism of photocatalytic degradation was also proposed. Moreover, the formation of multi-heterojunctions with large specific surface area facilitated the generation, separation and reaction of photoinduced electron-hole pairs. This work provided a new strategy to design multi-heterojunction photocatalysts for environmental remediation.