Z-type heterojunction degradation of tetracycline by 2D g-C₃N₄ with 3D oxygen vacancy Bi₂WO₆

Photocatalytic degradation is a promising strategy for environmental remediation. Graphitic carbon nitride (g-C₃N₄) is the most extensively reported metal-free material. Hierarchical flower-shaped Bi₂WO₆ particles were obtained using a simple hydrothermal method, with petals of flower-like Bi₂WO₆ with oxygen vacancies (Bi₂WO₆ OVs) with controlled content successfully decorated on g-C₃N₄ nanosheets. A novel Z-scheme 2D/3D heterojunction photocatalyst, g-C₃N₄/Bi₂WO₆ OV, was successfully prepared, with its composition and structure studied using a series of material characterization techniques. Compared to single g-C₃N₄ and Bi₂WO₆ OVs, the g-C₃N₄/Bi₂WO₆ OVs exhibited improved photocatalytic activity for the degradation of tetracycline, with a degradation rate of more than 90%. Moreover, electron paramagnetic resonance spectroscopy, X-ray photoelectron spectroscopy, and Mott-Schottky measurements suggest that a Z-scheme heterojunction formed between the g-C₃N₄ nanosheets and Bi₂WO₆ OV floral forms and that the photoinduced electrons in Bi₂WO₆ OVs bind to holes in g-C₃N₄, thus enhancing the extraction and utilization of carriers under photoexcitation. Hence, this study presents an effective method for constructing 2D/3D heterojunctions for solar fuel conversion and photocatalytic water treatment.