Visible-light-responsive Z-scheme α-Fe2O3/SWCNT/NH2-MIL-125 heterojunction for boosted photodegradation of ofloxacin

In this study, Fe2O3/SWCNT/NH2-MIL-125 (Fe2O3/CNT/MIL) heterostructure was described for ofloxacin (OFX) antibiotics degradation under visible light irradiation (lambda > 420 nm). Firstly, alpha-Fe2O3-derived from MIL-88(Fe) was fabricated via carbonization under an air atmosphere and combined with single-walled CNTs (SWCNTs) to improve electrical conductivity. Subsequently, microcrystals NH2-MIL-125 were successfully decorated on alpha-Fe2O3/SWCNT surface under solvothermal methods to obtain a new type of the Z-scheme Fe2O3/CNT/MIL heterojunction. The photodegradation rate of OFX in the presence of Fe2O3/CNT/MIL nanocomposite reached 99.3 % in 65 min with a rate constant of 0.065 min(-1). This decent photocatalytic activity is principally attributed that the introduction of the alpha-Fe2O3 and NH2-MIL-125 can notably boost the separation of photogenerated electron-hole pairs. Furthermore, loading SWCNTs boosted the electrical conductivity of alpha-Fe2O3 and NH2-MIL-125 to improve photodegradation activity. Also, trapping experiments revealed that (OH)-O-center dot and O-center dot(2)- were the main active species, which can also be verified by the detection of electron paramagnetic resonance (EPR). Our findings provide novel ideas for the development of visible-light-responsive materials for improvement in the advanced oxidation process (AOP).

Automated summary

In this study, a Fe2O3/CNT/MIL heterostructure was developed for the degradation of ofloxacin (OFX) antibiotics under visible light irradiation (λ > 420 nm). The introduction of α-Fe2O3 and NH2-MIL-125 enhanced the separation of photogenerated electron-hole pairs, resulting in a high photodegradation rate of OFX. The loading of SWCNTs improved the electrical conductivity of α-Fe2O3 and NH2-MIL-125, further enhancing the photodegradation activity. (OH)· and O·2- were identified as the main active species responsible for the degradation process.