BaTiO₃/I@g-C₃N₄ Z-Scheme Heterojunctions With Superior Charge Transfer for Efficient Photocatalytic Antibiotic Wastewater Treatment

Exploring heterojunction formation between conjugated organic polymer and metal-based semiconductors with promoted charge transfer and efficient spatial charge separation has proven to be quite successful in reinforcing photocatalytic wastewater treatment. Focusing on the removal of sulfonamide antibiotics from water, herein, we report BaTiO₃/I@g-C₃N₄ Z-scheme heterojunction photocatalyst for degradation of sulfamethazine (SMZ) pollutant. The optimized heterojunction 25ICN/BT exhibits superior 94.5% removal of SMZ in 90 min, which is nearly 11 and 5 times faster than BT and pristine I@g-C₃N₄ under visible light. The good repeatability of 25BT/ICN was proved by four-cycle experiments. The remarkable improvement in photocatalytic activity was due to effective Z-scheme transfer, diminished recombination, high charge transfer capacity, and redox capability. This was ascertained by electrochemical experiments and photoluminescence measurements. Furthermore, the degradation intermediates formed during the photocatalytic oxidation of SMZ were detected via liquid chromatography-mass spectrometry, and a suitable degradation pathway was suggested. The heterojunctions showed excellent performance in river, lake, and tap water and for other antibiotic pollutants. The radical quenching experiments and band structure analysis inferred ^•O₂⁻ radicals as main active species. This work lays down new perspectives on hierarchical heterostructures for the superior removal of noxious antibiotic contaminants.