Environment-friendly Ag/CDots/g-C^sub 3^N^sub 4^ photocatalysts: Remarkably enhanced photocatalytic tetracycline degradation in visible light

The g-C¢sub¢3¤sub¤N¢sub¢4¤sub¤ was widely used in water purification recently. However, the further application was severely suppressed because of the rapid electron-hole recombination and low visible-light utilization efficiency. Herein, we fabricated the three-component Ag/CDots/g-C¢sub¢3¤sub¤N¢sub¢4¤sub¤ nanocomposites which effectively enhanced the photodegradation of tetracycline (TC) under visible light irritation (～93.4% in 60 min), compared with Ag/g-C¢sub¢3¤sub¤N¢sub¢4¤sub¤ (∼76.1%), CDots/g-C¢sub¢3¤sub¤N¢sub¢4¤sub¤ (∼63.8%) and g-C¢sub¢3¤sub¤N¢sub¢4¤sub¤ (∼44.2%). The morphology, structural and compositional information of Ag/CDots/g-C¢sub¢3¤sub¤N¢sub¢4¤sub¤ was observed as well as the optical and electric properties, and the photocatalytic mechanism was revealed in detail. The addition of CDots could effectively increase light absorption efficiency, accelerate electron transfer and separation, and act as an electron-reservoir center. The presence of Ag had increased electron density via SPR effect, further enhancing the photocatalytic performance. The Ag/CDots/g-C¢sub¢3¤sub¤N¢sub¢4¤sub¤ also showed great stability and reusability with ignorable change in five recycle. Besides, the toxicity assessment proved the good biocompatibility and low cytotoxicity of Ag/CDots/g-C¢sub¢3¤sub¤N¢sub¢4¤sub¤. The study indicated that the successful synthesis of Ag/CDots/g-C¢sub¢3¤sub¤N¢sub¢4¤sub¤ paved way to water purification.