Sunlight-activated 3D-mesoporous-flowerlike Cl-Br bismuth oxides nanosheet solid solution: In situ EG-thermal-sonication synthesis with excellent photodecomposition of ciprofloxacin.

In this research, a group of BiOX (Cl:Br) nanosheet solid solution with various Cl/Br molar ratios have been fabricated using a facile one-pot in-situ thermal-sonication method. The crystal phases structure, elemental composition, morphology, specific surface area and optical features of as-synthesized photocatalyst were explored by XRD, EDX, FESEM, HRTEM, AFM, BET-BJH, and DRS techniques. The photocatalytic activity of nanophotocatalysts was investigated by photodegradation of ciprofloxacin as a model pharmaceutical pollutant under simulated solar light illumination. The scavenging effect was studied by using tTriethanolamine and 2-propanol to evaluate the roles of holes and hydroxyl radicals as main active species. All the samples showed higher photocatalytic activity compared to pristine BiOCl and BiOBr. Among the solid solutions, BiOX (Cl:Br = 1:3)-U sample exhibited excellent photocatalytic performance by 100% degradation efficiency of ciprofloxacin within 120 min. The outstanding photocatalytic activity of BiOX (Cl:Br = 1:3)-U might be ascribed to the large specific surface area, suitable morphology and band gap, effective separation of the photo-generated electron-hole pairs and the existence of the meso-size pores in structure. Moreover, results demonstrated that the presence of ultrasound irradiations and generated microjets during the synthesis step could appreciably improve the photocatalytic performance. After 4 cycles, there was no significant change in photocatalytic activity that confirms the high stability of BiOX (Cl:Br = 1:3)-U mesoporous nanophotocatalyst. Besides, the influence of operating parameters on the degradation efficiency and the possible photocatalytic mechanism was examined.