g-C3N4 supported Ag/AgCl@MIL-88A MOF based triple composites for highly efficient diuron photodegradation under visible LED light irradiation

In this work, a series of g-C3N4 supported Ag/AgCl doped MIL-88A composites were synthesized and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), and photoluminescence spectroscopy (PL). The photocatalytic performances of as-prepared composites were examined by the photodegradation of diuron (DRN), which is used as an herbicide in agriculture. The composites exhibit exceptional visible-light photocatalytic activities for photodegradation of DRN with complete degradation within 60 min in the absence of oxidants. However, in the presence of H2O2 or persulfate, complete degradation of DRN was achieved in 15 min and 30 min, respectively. The photocatalyst also gave very high conversions in water containing dissolved inorganic salts and natural organic matter (NOM). The Ag/AgCl@MIL-88A/g-C3N4 composite retained excellent photocatalytic properties after repeated use. Radical trapping experiments revealed that the most important reactive species in the photodegradation were O-2(-center dot) and h(+). Role of active radicals were discussed via proposed degradation mechanism for the degradation of DRN in the presence of MIL-88A/g-C3N4 and Ag/AgCl@MIL-88A/g-C3N4.