Direct Z-scheme Bi2MoO6/UiO-66-NH2 heterojunctions for enhanced photocatalytic degradation of ofloxacin and ciprofloxacin under visible light

In this work, direct Z-scheme Bi2MoO6/UiO-66-NH2 (BUN-x) heterojunctions are successfully synthesized by a facile solvothermal method. The photocatalytic activities of the flower-like BUN-x composites are evaluated using typical fluoroquinolone antibiotics, ofloxacin (OFL) and ciprofloxacin (CIP), under visible light. Almost all composites exhibit better adsorption-photodegradation performance than pure components. The OFL and CIP removal efficiencies using BUN-100 composite are the highest (100.0% and 96.0%, respectively) within 90 min. This good photocatalytic performance is attributed to the Z-scheme charge transfer between Bi2MoO6 and UiO-66-NH2. Moreover, good stability and adaptability of BUN-100 are verified. Additionally, trapping experiments and electron spin resonance analyses are performed to identify the active species generated by BUN-100 (∙OH, h+, and ∙O2-). Comparisons are made between the active sites and pathways of OFL and CIP based on DFT calculations and intermediates analysis. QSAR predicts that the degradation processes of both OFL and CIP can gradually reduce toxicity.