2D/2D nitrogen-rich graphitic carbon nitride coupled Bi₂WO₆ S-scheme heterojunction for boosting photodegradation of tetracycline: Influencing factors, intermediates, and insights into the mechanism

A novel two-dimensional 2D/2D Bi₂WO₆@g-C₃N₅ (BiW@CN) step-scheme (S-scheme) heterojunction was designed and fabricated via simple wet chemical approach. The crystal structure, morphology, composition, and optical properties were systematically investigated by multiple techniques. Apparently, BiW@CN heterojunction when compared to bare g-C₃N₅ and Bi₂WO₆ has remarkable light-harvesting capability and exhibits better photocatalytic performance toward tetracycline degradation. The excellent enhancement activity of the BiW@CN is due to the formation of S-scheme heterojunction, which not only promotes the spatial charge separation but also endows the reduction power of photogenerated electrons. Notably, the S-scheme charge transfer mechanism was explored by quenching experiments, electron spin resonance, and X-ray photoelectron spectroscopy analysis. Finally, the study proposes possible TC degradation pathways by identifying the transformation products. This research provides a new platform for efficient 2D/2D S-scheme heterojunctions for environmental water pollution treatments.