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

Abstract

In this study, carbon dot-sensitized Ti³⁺ self-doped TiO₂ dual-phase (TiO_2−x/CDs) composite photocatalytic systems were successfully constructed using a low-temperature hydrothermal method. The TiO_2−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.