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 photo-Fenton 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 (·OH), superoxide radicals (·O2–) 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.