Fabrication of S-scheme FeIn2S4/Fe2O3 heterostructures with improved photo-Fenton catalytic activity for removing pharmacologically active compounds

Environmental pollution caused by discharged pharmacologically active compounds (PACs) has recently aroused widespread concern. Herein, novel FeIn2S4/Fe2O3 (FISFO) heterostructures were fabricated via in situ interfacial engineering. The synthetic FISFO samples facilitate efficient charge migration driven by S-scheme heterogeneous interfaces due to their strong interfacial coupling, as evidenced by band structure analysis and density functional theory (DFT) calculations. The optimal hybrid sample FISFO-3 possesses the highest photo-Fenton catalytic activity, achieving a degradation efficiency of 97.35 % for tetracycline hydrochloride (TCH). It also exhibits universal degradation abilities toward the removal of ciprofloxacin, ceftiofur sodium, and nitrofurantoin via the photo-Fenton reaction. Electron paramagnetic resonance (EPR) and active species quenching experiments verified that hydroxyl radicals and photogenerated holes were the main active species involved in the TCH degradation. The possible degradation pathways for TCH removal were determined via liquid chromatography-mass spectrometry (LC-MS). Overall, this study provides an important insight into design of high-efficiency photo- Fenton catalysts for removing PACs.