Facile fabrication of multi-walled carbon nanotubes (MWCNTs)/α-Bi2O3 nanosheets composite with enhanced photocatalytic activity for doxycycline degradation under visible light irradiation

In this work, multi-walled carbon nanotubes (MWCNTs)/α-Bi2O3 nanosheets nanocomposites were firstly fabricated and used for photocatalytic degradation of doxycycline (DOX) under visible light. These nanocomposites were characterized by a series of techniques. XRD patterns illustrated α-Bi2O3 and MWCNTs/α-Bi2O3 composites were successfully synthesized. The nanotubular structure of MWCNTs and the nanosheet structure of α-Bi2O3 were determined by SEM and TEM. The compositional analysis of as-synthesized materials was obtained by XPS, and the results showed that MWCNTs and α-Bi2O3 were tightly combined. DRS spectra indicated that the introduction of MWCNTs broadened the light absorption range of the photocatalysts. The BET tests and photocatalysis experiments confirmed that the introduction of MWCNTs not only increases the specific surface area of the photocatalyst, but also increases its photocatalytic activity. When mass ratio of MWCNTs to α-Bi2O3 was 0.15, the catalyst showed the best degradation ability with 91% DOX was degraded at 120 min. The trapping experiments and electron spin resonance tests demonstrated that the ·O2− and ·OH radicals were the main reactive species in DOX degradation process. This work has prepared an economical MWCNTs/α-Bi2O3 photocatalyst by a simple solvothermal–calcination method, which has the potential application of pharmaceutical pollutants removal in water.