One-step construction of NH2-UiO-66 based heterojunction photocatalysts for adsorption–photocatalytic synergistic removal of antibiotics

Abstract

Metal–organic frameworks (MOFs), as novel crystalline materials, exhibit notable photocatalytic activity and exceptional adsorption capabilities. However, their low charge separation efficiency still limits their photocatalytic performance. Herein, NH₂-UiO-66/BiOCl composites were synthesized through a one-step green grinding method, effectively integrating adsorption and photocatalytic degradation mechanisms. The NH₂-UiO-66/BiOCl-50% composite demonstrated outstanding degradation efficiency (96.84%) for ciprofloxacin (CIP) within 60 min, with a rate constant (0.0432 min⁻¹) that is 3.6 and 2.1 times those of NH₂-UiO-66 and BiOCl, respectively. The removal performance of NH₂-UiO-66/BiOCl for CIP and the underlying adsorption–photocatalytic degradation mechanisms were thoroughly investigated in various water environments. The remarkable degradation performance is attributed to the excellent adsorption capacity and the effective formation of a heterojunction between NH₂-UiO-66 and BiOCl, which enhances electron–hole separation and transfer efficiency. The stability of the photocatalyst is demonstrated by cyclic testing. Moreover, ˙O₂⁻ was identified as the main active species and the photocatalytic mechanisms of the composite were elucidated. This work provides valuable insights into the synergistic integration of adsorption and photocatalytic degradation for the treatment of antibiotic-contaminated wastewater.