Photocatalytic hydrogen evolution of carbon quantum dots-modified TiO2 achieved by green synthesis

Carbon quantum dots (C-dots) play an integral part in various photocatalytic systems due to their low toxicity, high photoluminescence, small size, conductivity, and light-emission properties. In this study, C-dots acting as effective sensitizers were synthesized via a green route using Aspergillus sp. mold as the carbon source and, for the first time, integrated with TiO₂ to construct a composite system for photocatalytic hydrogen evolution (PHE). The PHE activity of the C-dots-sensitized TiO₂ was measured at 1.9 mmol g⁻¹ h⁻¹, which increased to 2.6 mmol g⁻¹ h⁻¹ with the addition of a Pt co-catalyst. Herein, C-dots served as sensitizers on TiO2 to increase the visible light absorption, and the enhanced PHE performance is attributed to synergistic interaction between the C-dots and TiO₂, which not only broadens the light absorption range but also facilitates more efficient charge transport. Consequently, C-dots enhance the effectiveness of TiO₂, enabling it to perform more efficiently in photocatalytic reactions, particularly hydrogen evolution systems.