Construction of multifunctional dual Z-scheme composites with enhanced photocatalytic activities for degradation of ciprofloxacin

Visible-light-driven (VLD) photocatalysis has aroused extensive attention due to their great potential in applications concerning energy crisis and environmental pollution. Hence, for the first time, VLD and magnetic recyclable dual Z-scheme NiFe2O4/Bi2WO6/AgI (NBA) composites were prepared via a hydrothermal method to obtain NiFe2O4/Bi2WO6 (NB) following an in situ deposition of AgI. The as-prepared NBA catalysts exhibit excellent photocatalytic performance for the degradation of ciprofloxacin (CIP) compared to the pristine NiFe2O4, Bi2WO6 or AgI under visible-light (VL) illumination. Among them, the 75%NiFe2O4/Bi2WO6/AgI (75NBA) composite exhibits optimal photocatalytic efficiency, which is 1.67, 1.51, 1.83 times higher than those of the pristine NiFe2O4, Bi2WO6 and AgI within 60 min, respectively. The high catalytic efficiency may be ascribed to the synergistic effect of the increased VL harvesting and dual Z-Scheme transmission paths in 75NBA system. Furthermore, trapping experiments and electrochemical impedance spectroscopy (ESR) analysis verify the co-existing of center dot OH and center dot O-2(-) in the 75NBA photocatalytic system. Additionally, the magnetic 75NBA can be rapidly separated from water by an external magnet. Based on the results from High performance liquid chromatography-mass spectrometry (HPLC-MS) analysis, four path ways towards the degradation of CIP are proposed. The highly efficient photocatalytic activity and magnetically reproducibility suggest that it is expected to be used in antibiotic wastewater treatment.

Automated summary

Visible-light-driven photocatalysis using magnetic recyclable dual Z-scheme NiFe2O4/Bi2WO6/AgI composites showed excellent photocatalytic performance for the degradation of ciprofloxacin compared to individual components. The 75%NiFe2O4/Bi2WO6/AgI composite exhibited the highest photocatalytic efficiency due to enhanced light absorption and dual Z-scheme transmission paths, suggesting its potential application in antibiotic wastewater treatment.