Graphene quantum dots decorated graphitic carbon nitride nanorods for photocatalytic removal of antibiotics

Abstract

The over-use of antibiotics has resulted in seriously environmental pollution. Metal-free photocatalysts have received tremendous attentions due to their environmental friendliness. Meanwhile, morphology and structure of photocatalysts have significant influence on their photocatalytic performance. Herein, we report a metal-free composite photocatalyst of 0-dimensional (0D) graphene quantum dots (GQDs) decorated graphitic carbon nitride nanorods (g-CNNR) that was obtained by a hydrothermal treatment. Characterizations of physicochemical properties demonstrate that this GQDs/g-CNNR photocatalyst has a high crystallization level, enhanced visible light absorption and a staggered band alignment, which can promote the formation, the transportation and the separation of photo-excited electrons and holes. These prominent advantages bring improved photocatalytic activity of the GQDs/g-CNNR for efficient removal of antibiotics. Its photocatalytic reaction rate is 3.46 and 2.03 times higher than those of the pristine graphitic carbon nitride (g-C3N4) and the g-CNNR, respectively. Furthermore, this composite photocatalyst has good application universality for decomposing other antibiotics, and also possesses excellent stability and reusability. We further proved that photo-induced holes and superoxide radicals are main active species in the photocatalytic process. Our findings suggest that efficient g-C3N4 based photocatalysts can be well fabricated by structural regulation of g-C3N4 and formation of tightly contacted interface between g-C3N4 and GQDs.