Ultrathin K-doped g-CN/BiOBr heterojunctions with S-scheme charge transfer for efficient photodegradation of tetracycline.

Residual tetracycline (TC) in aquatic ecosystems poses a significant risk to the health of both flora and fauna. Advanced catalysts with strong photocatalytic capabilities have emerged as a promising solution for not only TC degradation but also water purification. Here, the photocatalytic destruction (PCD) of TC has been investigated using ultrathin potassium-doped g-CN/BiOBr heterojunctions (KCNx/By, where x and y are the percent mass ratio values of KOH/melamine and KCN/BiOBr, respectively). All PCD tests have been conducted under 300 W of illumination from a xenon lamp with a light intensity at the catalyst surface of 280 mW. The PCD efficiencies of the formulated KCN2/B3 (92.7 % within 30 min) are approximately 1.62 and 1.34-fold higher than those of KCN2 and BiOBr, respectively. KCN2/B3 achieves the strongest performance against TC in terms of removal-reaction kinetics (r: 0.209 mmol g h) and space-time yield (5.90E-03 molecules·photon·g) among the common photocatalysts built by g-CN- or BiOBr. The superior photocatalytic activity of KCN2/B3 can be attributed to the S-scheme charge-transmission pathway, which efficiently preserves photogenerated electrons (B3: reduction catalyst) and holes (KCN2: oxidation photocatalyst). This newly fabricated 2D/2D nanocomposite can be used in the construction of a scalable photocatalytic system for the remediation of TC in wastewater.