Construction of 3D/2D ZnFe2O4/g-C3N4 S-scheme heterojunction for efficient photo-Fenton degradation of tetracycline hydrochloride

Heterogeneous photo-Fenton catalytic reaction is a promising advanced oxidation technology for environment remediation. Herein, 3D/2D ZnFe2O4/g-C3N4 heterojunctions were successfully fabricated and applied in photoFenton degrading tetracycline hydrochloride (TC). The crystalline phases, morphologies, microstructures, specific surface areas and optical properties of as-prepared catalysts were investigated by multiple inspect techniques. After comparison and optimizing, the ZFO/NCN-2 (4.8 wt% ZnFe2O4/g-C3N4) heterojunction displayed the best photo-Fenton catalytic activity for TC degradation, with the degradation efficiency of 94.4 % in 40 mins. The implementation of active species trapping tests, photoluminescence (PL) spectra, electron spin resonance (ESR) measurements and density functional theory (DFT) calculations not only confirmed that the hydroxyl radicals (center dot OH), superoxide radicals (center dot O-2(-)) and holes (h(+)) were all participated in the photo-Fenton reaction, but also evidenced an S-scheme photogenerated charge transfer route. The effective charge separation and accelerated Fe3+/Fe2+ cycles were responsible for the outstanding photo-Fenton activity. Additionally, the plausible degradation pathways of TC were reasonably proposed in view of the high-performance liquid chromatography mass spectrometry (HPLC-MS) analytic results. The current work presented a potentially efficient photo-Fenton catalyst for the decontamination of antibiotic wastewater.

Automated summary

In this study, 3D/2D ZnFe2O4/g-C3N4 heterojunctions were successfully prepared and used as efficient catalysts for the photo-Fenton degradation of tetracycline hydrochloride. Various characterization techniques were employed to examine the properties of the catalysts. The ZFO/NCN-2 heterojunction showed the best catalytic activity, with a degradation efficiency of 94.4% in 40 minutes. The involvement of different active species and the charge transfer route were confirmed through experiments and calculations. The excellent photo-Fenton activity was attributed to the effective charge separation and accelerated Fe3+/Fe2+ cycles. The degradation pathways of tetracycline hydrochloride were proposed based on HPLC-MS analysis.