Amine-functionalized metal–organic framework integrated bismuth tungstate (Bi2WO6/NH2-UiO-66) composite for the enhanced solar-driven photocatalytic degradation of ciprofloxacin molecules

Abstract

An amine-functionalized metal–organic framework integrated bismuth tungstate (Bi₂WO₆/NH₂-UiO-66) nanocomposite has been developed by the in situ growth of NH₂-UiO-66 on Bi₂WO₆ micro/nanoflowers via a hydrothermal technique and its photocatalytic performance towards ciprofloxacin degradation under solar light irradiation has been studied. The integration of NH₂-UiO-66 with Bi₂WO₆ micro/nanoflowers extends its absorption-edge towards the visible light region (∼470 nm) and the specific surface area of the Bi₂WO₆/NH₂-UiO-66 composite is estimated to be 113.6 m² g⁻¹. It is observed that the amine linkage established a strong interfacial contact between the NH₂-UiO-66 and Bi₂WO₆ micro/nanoflowers and formed a Z-scheme heterojunction in the composite. The Z-scheme heterojunction is found to lead to the effective photo-induced electron–hole pair separation and charge transfer kinetics, as well as providing strong oxidation and reduction sites in the composites, which leads to the degradation of around 83.1% of ciprofloxacin in 60 min. In addition, the h⁺ and O₂˙⁻ radicals are identified as major reactive species responsible for the photocatalytic process in the Bi₂WO₆/NH₂-UiO-66 composite, and thereby a possible photocatalytic mechanism is also proposed.