Visible-light degradation of antibiotics catalyzed by titania/zirconia/graphitic carbon nitride ternary nanocomposites: a combined experimental and theoretical study

Development of low-cost, high-performance photocatalysts for the effective degradation of antibiotics in wastewater is critical for environmental remediation. In this work, titanium dioxide/zirconium dioxide/graphitic carbon nitride (TiO2/ZrO2/g-C3N4) ternary composites are fabricated via a facile hydrothermal procedure, and photocatalytically active towards the degradation of berberine hydrochloride under visible light illumination. The performance is found to increase with the Ti:Zr atomic ratio in the nanocomposites, and obviously enhanced in comparison to that of the binary TiO2/g-C3N4 counterpart, due to the formation of type I/II heterojunctions that help separate the photogenerated electron-hole pairs and produce superoxide and hydroxy radicals. The mechanistic pathways are unraveled by a deliberate integration of liquid chromatography-mass spectrometry measurements with theoretical calculations of the condensed Fukui index. Furthermore, the ecotoxicity of the reaction intermediates is examined by utilizing the Toxicity Estimation Software Tool (TEST) and quantitative structure activity relationship calculations (QSAR).