Highly efficient photocatalysis toward tetracycline under simulated solar-light by Ag+-CDs-Bi2WO6: Synergistic effects of silver ions and carbon dots

Abstract A novel Ag + -carbon dots (CDs)-Bi 2 WO 6 ternary composite with excellent solar-light-driven photocatalytic performance was firstly synthesized using hydrothermal-impregnation method. It was used to degrade tetracycline (TC) in water. 5Ag + -CDs2.5-Bi 2 WO 6 (0.5 g/L) displayed superior photocatalytic efficiency with nearly 100% removal of TC (20 mg/L) in 20 min and 64% mineralization in 90 min. The degradation reaction coefficient ( k obs ) was approximately 1.8 times higher than pure Bi 2 WO 6 as a result of the synergistic effects of Ag + and CDs co-doped on the surface of Bi 2 WO 6 . Both CDs and Ag + could effectively trap the photoexcited electrons generated by Bi 2 WO 6 , promoting the charge transfer and separation of electron-hole pairs. In addition, after accepting the electrons, Ag + was photoreduced to Ag attached to Bi 2 WO 6 nanosheets. The plasmonic-Ag and CDs displayed stronger utilization of visible light capacities. Moreover, Ag + itself also served as an oxidant to degrade TC in water directly. Electron transfer mainly occurred in the order of Bi 2 WO 6  → Ag → CDs. Superoxide radical species and photogenerated holes were predominant reactive species responsible for the photodegradation of TC. The study indicated that novel Ag + -CDs-Bi 2 WO 6 has a great potential for rapid and efficient treatment of organic pollutants in water.