Synergistic degradation of tetracycline by CDs decorated g-C3N4 under LED light irradiation combined with the persulfate-based advanced oxidation process

Graphitic carbon nitride (g-C3N4, CN) has been applied to degrade a variety of pollutants. However, two major defects, the low utilization of light energy and the high recombination of photogenerated electron and hole (e--h+) pairs, need to be improved. In this study, a LED-light-driven photocatalyst, carbon dots decorated graphitic carbon nitride (CNC), was successfully prepared by simple thermal polymerization. Due to the remarkable up-conversion photoluminescence properties and superior charge transport capability of CDs, CNC had higher e--h+ separation efficiency and broader visible light response. In this experiment, a combined process of CNC and persulfate (CNC/PS) was used for tetracycline (TC) degradation. High-efficient photocatalytic degradation rate of 81.9% was obtained in the CNC/PS system. Moreover, the mechanism analysis indicated that the reaction between PS and photogenerated e- effectively promoted the separation of electrons-holes pairs, thereby enhancing the formation of dominant active radicals •O2- and holes for TC degradation.