In situ construction of N-rich carbon nitride (C₃N₅)/silver phosphate (Ag₃PO₄) S-scheme heterojunctions for the efficient photocatalytic removal of levofloxacin antibiotic and RhB

Building step-scheme (S-scheme) heterojunctions has recently emerged as a highly effective approach for developing superior photocatalysts for water purification. Herein, a C₃N₅/Ag₃PO₄ (CA) S-scheme heterojunction was prepared by in situ growth of Ag₃PO₄ nanoparticles on 2D C₃N₅ nanosheets. Notably, under visible-light irridiation, CA exhibited significantly higher activity in the photodegradation of LEVO, which is about 28.38, 2.41, and 2.14 times higher than the rates for C₃N₅, Ag₃PO₄, and the mixture, respectively. Based on the radical scavenging experiments, the mechanism for enhanced photocatalytic performance has been analyzed, is attributed to improved interfacial charge separation, the elevated redox potential of photon-generated electrons and holes, and the increased generation of active species resulting from the S-scheme transfer of photoinduced carriers. Additionally, CA demonstrates greater stability than either C₃N₅ or Ag₃PO₄ alone in the photo-oxidation of LEVO and the photodegradation of RhB. In essence, this study not only deepens our comprehension of the photocatalytic mechanism of CA, but also pioneers a novel concept for the development of highly effective and stable S-type heterojunction photocatalysts.