Carbon dot-sensitized urchin-like Ti3+ self-doped TiO2 photocatalysts with enhanced photoredox ability for highly efficient removal of Cr6+ and RhB

In this study, carbon dot-sensitized Ti3+ self-doped TiO2 dual-phase (TiO2-x/CDs) composite photocatalytic systems were successfully constructed using a low-temperature hydrothermal method. The TiO2-x photocatalyst showed improved photocatalytic activities for the removal of Cr6+ and RhB under visible light. Remarkably, RhB (10 mg L-1) and Cr6+ (40 mg L-1) solutions were degraded completely in 30 and 120 min, respectively, by the composite photocatalyst (1 g L-1) under visible-light irradiation. These results were much better than those of commercial P25. This fascinating photocatalytic performance was attributed to the improved photogenerated electron-hole separation efficiency from the synergistic effects of rutile and anatase, and the reduced photogenerated charge carrier recombination and facilitated visible-light absorption from the introduced CDs. This study provides a promising approach for the treatment of real wastewater using sunlight.