Integrating optimal amount of carbon dots in g-C3N4 for enhanced visible light photocatalytic H2 evolution

Carbon dots (CDs) hold great promise for photocatalytic application owning to their low production cost, unique optical properties, as well as excellent stability and conductivity. Integrating CDs in graphite carbon nitride (g-C₃N₄) nanosheets helps to broaden visible light absorption, retard charge recombination and promote photoelectrons transport. Herein, we demonstrated a simple strategy to introduce CDs on g-C₃N₄ nanosheets by hydrothermal treatment of ginkgo leaves followed by thermal polymerization of urea. We found that there was were two volcano-trends in the photocatalytic H₂ evolution rate with the increase of CDs loading. As a result, the optimized CDs/g-C₃N₄ nanocomposites demonstrated a superior hydrogen evolution rate as high as 3.12 mmol g^?1·h^?1 and 14.4% apparent quantum efficiency (AQE) was achieved at 420 nm visible light irradiation. The contribution of CDs towards the photocatalytic hydrogen evolution enhancement was discussed in depth via experiment characterization and Density functional theory (DFT) calculation. This work may shed light on the rational design and bottom-up synthesis of eco-friendly energy conversion materials with high-performance and low cost.