Mesoporous TiO2 modified with carbon quantum dots as a high-performance visible light photocatalyst

We report a preparation method for visible light responsive Carbon Quantum Dots (CQDs) embedded in mesoporous TiO2 materials. The as-prepared mesoporous TiO2 (meso-Ti-450) material is a member of the recently designed University of Connecticut (UCT) mesoporous materials family. The UCT materials were synthesized based on sol-gel chemistry. The nanoparticles are randomly packed in inverse surfactant micelles and mesopores are formed by interconnected intraparticles. To achieve full usage of the visible region of sunlight (>400 nm), CQDs were introduced without destroying the mesopores. The photocatalytic performance of the CQDs/meso-Ti-450 was investigated by the degradation of methylene blue. Due to the up-conversion property and electron withdrawing property of CQDs, the photocatalytic activity of the composite material was largely enhanced under visible light irradiation. The highest photocatalytic activity was achieved by 5% CQDs/meso-Ti-450 in an hour. Compared to commercial P25, which is capable of removing 10% methylene blue (MB) under visible light conditions, the 5% CQDs/meso-Ti-450 can mostly remove MB (98%) under the same conditions. To date, the usage of mesoporous titanium oxide and carbon material composites for dye degradation under visible light has not been reported.