Ultrathin Ag2WO4-coated P-doped g-C3N4 nanosheets with remarkable photocatalytic performance for indomethacin degradation

Abstract As a metal-free photocatalyst, the photocatalytic activity of graphitic carbon nitride (g-C3N4) remains restricted due to an insufficient visible-light absorption capacity, the rapid recombination of photoinduced carriers, and low surface area. Consequently, P-doped g-C3N4 (PCN) was successfully prepared via a single -step thermal polymerization technique using phytic acid biomass and urea, which exhibited remarkable photocatalytic activity for the degradation of indometacin (IDM). The IDM degradation rate was 7.1 times greater than that of pristine g-C3N4 (CN). Furthermore, Ag2WO4 was loaded onto the surface of the PCN, which formed a Z-scheme heterostructure that promoted the separation of photogenerated carriers. According to analyses of the chemical binding states of PCN, P atoms replaced carbon atoms in the CN framework. According to electron localization function analysis, the low ELF values of P-N facilitated the transfer of photoelectrons. The results of active species scavenging experiments confirmed that superoxide radicals were the primary active species in the photocatalytic degradation system. Finally, the photocatalytic degradation pathways of IDM were predicted through the identification of by-products and IDM reaction sites.