An innovative Z-scheme g-C3N4/ZnO/NiFe2O4 heterostructure for the concomitant photocatalytic removal and real-time monitoring of noxious fluoroquinolones

A novel ternary heterostructure with dual Z-scheme g-C3N4/ZnO/NiFe2O4 (CZN) was designed via simple sonication-calcination strategy and the synchronized heterostructure was exploited for fluorescence sensing as well as visible-light driven photocatalytic degradation of fluoroquinolone (FQs) antibiotics; i.e. levofloxacin (LVX), ciprofloxacin (CPF) and ofloxacin (OFL). The comparative appraisal of ternary composites with g-C3N4/ ZnO was carried out for the degradation of FQs and augmented photocatalytic activity was observed by addition of NiFe2O4 nanoparticles to g-C3N4/ZnO composite. The degradation studies for synthesized heterostructures were observed to follow pseudo first order kinetics and rate constant values for CZN1 heterostructure were found to be 1.26, 1.14 and 1.67 times than that of g-C3N4/ZnO composite for LVX, OFL and CPF, respectively. Enhanced photocatalytic activity of ternary heterostructure was ascribed to dual Z-scheme charge transfer mechanism followed by heterostructure that resulted in amended visible light absorption capability, alleviated charge separation and diminished photo-induced electron-hole pair recombination rate. Additionally, the synthesized heterostructure was utilized for selective fluorescence sensing of FQs. The sensor proved to be highly selective and sensitive for the detection of FQs with imperasive limit of detection i.e. as low as 0.12, 0.08 and 0.18 mu M for LVX, OFL and CPF respectively, besides a broader linear range of 0.02-1.00 mu M was observed for FQs. Real sample analysis confirmed the practicality of constructed fluorescence sensor. Thus, the fabricated heterostructures provides a new notion of contriving multifarious components to innocous system for environmental remediation.

Automated summary

A novel ternary heterostructure with dual Z-scheme g-C3N4/ZnO/NiFe2O4 was designed and synthesized, which showed enhanced photocatalytic activity for the degradation of fluoroquinolone antibiotics and selective fluorescence sensing. The improved photocatalytic activity was attributed to the dual Z-scheme charge transfer mechanism, resulting in enhanced visible light absorption and reduced recombination rate. The fluorescence sensor exhibited high selectivity and sensitivity for the detection of fluoroquinolones.