Graphitic carbon nitride (g-C₃N₄) is a representative photocatalyst, but the photocatalytic activity is often limited because of the easy recombination and slow migration of photogenerated charges. Herein, we have successfully prepared carbon quantum dots (CQDs) functionalized g-C₃N₄ (CCN) by a simple thermal polymerization method. Besides, the CQDs serving as a photosensitizer can enlarge the absorption range of visible light of the composite material. As a result, under the irradiation of visible light, the optimized CCN showed superior catalytic activity with a high H₂ production rate of 2321 μmol·g⁻¹·h⁻¹, which was almost about 7.4 times higher than that of bulk g-C₃N₄. Based on the systematic characterization and density functional theory (DFT) calculation, it was proved that the efficiencies of the separation and transfer of photogenerated charges were enhanced by the micro-regional heterostructure of CQDs and g-C₃N₄.

石墨碳氮化物（gC ₃ N ₄）是一种代表性的光催化剂，但由于易于重组和光生电荷迁移缓慢，因此光催化活性通常受到限制。在这里，我们已经通过简单的热聚合方法成功地制备了功能化的gC ₃ N ₄（CCN）的碳量子点（CQDs）。此外，用作光敏剂的CQD可以扩大复合材料对可见光的吸收范围。结果，在可见光的照射下，优化的CCN显示出优异的催化活性，具有2321μmol·g ^-1 ·h ^-1的高H ₂生成率。，几乎是块状gC ₃ N _4的7.4倍。通过系统表征和密度泛函理论（DFT）计算，证明了CQD和gC ₃ N ₄的微区异质结构提高了光生电荷的分离和转移效率。