In situ synthesis of Z-scheme Ag 3 PO 4 /CuBi 2 O 4 photocatalysts and enhanced photocatalytic performance for the degradation of tetracycline under visible light irradiation

The Ag3PO4/CuBi2O4 (ACBO) composites with a small quantity of Ag3PO4 nanoparticles (0.5–10 wt.%) were synthesized by an in situ precipitation method and characterized by XRD, SEM, EDS, TEM, BET, XPS, UV–vis absorption spectra, PL, EIS and ESR analysis. Obviously, all the ACBO photocatalysts exhibited significantly enhanced photocatalytic performances. Meanwhile, ACBO with 5 wt.% content of Ag3PO4 (ACBO-5) showed the highest photocatalytic activity, which is around 2.79 and 2.16-fold higher than that of pristine Ag3PO4 and CuBi2O4, respectively. The enhanced photocatalytic activity could be due to the efficient separation of photogenerated electron-hole pairs through the formation of Z-scheme system composed of Ag3PO4, Ag and CuBi2O4, in which a small quantity of reducible Ag nanoparticles acted as the charge transmission-bridge. Moreover, the high photocatalytic stability of as-synthesized ACBO heterojunction photocatalyst was obtained through five successive cycling experiments. Finally, a possible photocatalytic mechanism was also discussed.