▎ 摘　　要

Environmental pollution has become one of the greatest problems worldwide, and photocatalysts have attracted a great deal of attention as one solution to this problem. In the present study, we report a novel environmentally friendly property of graphene quantum dots (GQDs) as efficient nano-materials for the degradation of organic pollutant dyes based on the photocatalytic behavior of GQDs under visible-light irradiation. GQD samples were derived from citric acid by a pyrolysis procedure. The synthesized GQDs were characterized by various techniques including transmission electron microscopy, UV-Vis absorption, Raman spectroscopy, fluorescence spectroscopy, and zeta potential measurements. The photocatalytic degradation of Celestine Blue (CB) was studied using GQDs under visible light irradiation. The effect of pH value, contacting time, dosage of GQDs, and initial dye concentration on the degradation kinetics of CB was systematically investigated. MS analyses were conducted to determine the degradation products evolving during the photocatalytic degradation. The possible mechanisms of degradation of CB based on GQDs under visible light are discussed as well.