Enhanced photocatalytic activity of Cu2O for visible light-driven dye degradation by carbon quantum dots

Cuprous oxide (Cu2O), a p-type semiconductor material, plays an important role in photocatalysis, which has narrower band gap (~2.1 eV), abundant availability, and low toxicity. However, the applications of Cu2O are mainly restricted by its high recombination rate and low charge collection. Hence, it is of great significance to find an efficient method to improve the photocatalytic activity of Cu2O. In this work, the CQDs-loaded Cu2O nanocomposites (CQDs/Cu2O) were successfully obtained via hydrothermal method. It was worth noting that the CQDs/Cu2O nanocomposite displayed improved photocatalytic activity compared to that of pure Cu2O with a lower dosage (25 mg) under visible light, which could completely degrade the methylene blue in 8 min. The recycling experiments also showed that the photocatalytic activity still remained up to 90% after 8 cycles. In addition to the photodegradation of methylene blue, the CQDs/Cu2O nanocomposite also had an excellent antibacterial activity against Escherichia coli (100%, 30 min). These results demonstrated that introducing CQDs to Cu2O was a feasible method to improve the photocatalytic performance of Cu2O.