Coordination of Mg(II) Enhancing Photoinduced Oxidase-Like Activity of Carbon Dots for Efficient Degradation of Organic Dyes

Abstract

Water pollution caused by organic dyes not only seriously damages the ecological environment but also poses a great threat to human health. Herein, the doping of Mg(II) enhancing the photoinduced oxidase-like activity of carbon dots (CDs) in a wide pH range from 2.3 to 8.2 is reported. The Mg-CDs catalyze the generation of superoxide anions (O₂^•–) and singlet oxygen (¹O₂) from dissolved oxygen under light irradiation. Compared to CDs without Mg(II) doping, Mg-CDs exhibit much higher photoinduced oxidase-like activity (more than 250%) because the coordination of Mg(II) facilitates the content ratio of enol to ketone, enhancing the rigidity of the π-system and boosting the electron transition within CDs. A universal strategy for degrading organic dyes, including azo, triphenylmethane alkaline, and alkaline azo dyes, is constructed based on the remarkable photoinduced oxidase-like performance of Mg-CDs. The degradation rates of methyl orange, crystal violet, and rhodamine B are 92.2%, 96.5%, and 98.5%, respectively. Our findings provide a strategy to design desirable photoinduced nanozymes for water pollution control and demonstrate great potential of metal-doped CDs in photocatalysis.