Mechanism and degradation pathways insight of photocatalytic oxidation antibiotics by geometrical Ag/AgNbO3/BiVO4 plasmon Z-type heterojunction

Three-dimensions geometry-like plasmon Ag/AgNbO3/BiVO4 (Ag/ANO/BVO) Z-type heterojunction photocatalyst was synthesized by electrostatic self-assembly and photo-deposition method. Levofloxacin hydrochloride (LEF) became the target degradation object to evaluate photocatalytic activity. The 3-Ag/ANO/BVO showed the best photocatalytic properties compared with other as-synthesized catalysts. The apparent rate constant of 3-Ag/ANO/BVO was 0.0235 min−1, which separately was 47.00, 5.22, and 1.85 times higher than that of AgNbO3 (ANO), BiVO4 (BVO), and 40%-AgNbO3/BiVO4 (40-ANO/BVO). Several reaction parameters including catalyst dosage, initial LEF concentration, and reaction pH values were filtrated to investigate optimal photocatalytic reaction conditions of the 3-Ag/ANO/BVO composite. The elevated photocatalytic activity can be attributed to the effective migration and separation of photo-induced carriers on the contact interface due to the formation of Z-type heterojunction and broadened visible light absorption range by localized surface plasmon resonance (LSPR) in 3-Ag/ANO/BVO composite. Furthermore, formed intermediates during the photocatalytic oxidation of LEF molecules were detected via high-performance liquid chromatography-mass spectrometry (HPLC-MS). Ultimately, a plasmonic Z-type photocatalytic mechanism was verified through a variety of characterization tests and simulations method (finite difference time domain, FDTD).