Hydrothermal synthesis of carbon quantum dots using different precursors and their combination with TiO2 for enhanced photocatalytic activity

In this study, carbon quantum dots (CQDs) were successfully synthesized by a facile and green hydrothermal method, and further coupled with P25 (commercial TiO2) to form CQDs/P25 heterojunctions for enhanced photocatalytic activity. Two typical precursors, glucose and citric acid were selected as precursors for the synthesis of CQDs. The effects of precursors on the properties of CQDs and the photocatalytic activity of resultant CQDs/P25 was indeed investigated. The TEM, Raman and XPS analysis revealed the good combination of CQDs on the surface of P25. The photodegradation experiments indicated that CQDs/P25 exhibited enhanced photocatalytic performance than that of pure P25. In addition, with the better crystallinity of CQDs, the higher photocatalytic activity of CQDs/P25 was achieved. More importantly, based on the comprehensive and detailed discussion, the hydrothermal carbonization process of various precursors and the possible mechanism for the enhanced photocatalytic activity of different CQDs/P25 composites were significantly put forward.