Efficient visible-light driven photodegradation of sulfonamide antibiotics using a Z-scheme Ag2O/Bi-nicotinate nanocomposite

In this article, a two-dimensional bismuth complex (Bi-nic) was successfully synthesized via hydrothermal method using nicotinic acid (nic) as ligand. Then, Ag2O/Bi-nic nanocomposites with high visible-light driven photocatalytic activity were prepared at 60 degrees C, 80 degrees C and 100 degrees C, respectively, using Bi-nic as precursor. The synthesized Ag2O/Bi-nic nanocomposites were structurally characterized by XRD, FT-IR, EDX, XPS and DRS. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images displayed that Ag2O nanoparticles with an average size of 20 nm distributed on the surface of Bi-nic nano-sheets. The Ag2O/Bi-nic composites exhibited excellent photocatalytic activities in degradation of sulfonamide antibiotics under visible light. Under the catalysis of Ag2O/Bi-nic-80, the degradation efficiencies of sulfadiazine and sulfamethoxazole antibiotics were up to 94% and 93% after irradiating for 160 and 60 min, respectively. Ag2O and Bi-nic form a Z-scheme heterojunction structure in the Ag2O/Bi-nic nanocomposite, which allows electrons to transfer from the conduction band of Bi-nic to the valence band of Ag2O. It is revealed that the photogenerated e  and h+ can be effectively separated on the interfacial between Ag2O nanoparticle and Bi-nic nanosheet, which significantly improved the photocatalytic activity of Ag2O/Bi-nic.