C4N quantum dots/g-C3N4 nanosheets organic homogeneous structure self-assembly for efficient charge separation and photocatalytic hydrogen evolution

Abstract

Homogeneous structures play important roles in photogenerated charge separation in photocatalysis due to their structure similarity. Herein, C₄N quantum dots/graphite-phase carbon nitride nanosheets assembly (C₄NQDs/C₃N₄NSs) is achieved through a simple self-assembly process. Compared with original g-C₃N₄ nanosheets, C₄N quantum dots have a narrower band gap of 1.83 eV, which is conducive to the effective utilization of visible light. The photocatalytic hydrogen production of the resultant C₄NQDs/C₃N₄NSs assembly is up to 1980 μmol g⁻¹ h⁻¹ and the apparent quantum yield (AQY) can reach 32% at 365 nm, which is two times higher than that of original g-C₃N₄ nanosheets. This can be ascribed to the strong electron absorption activity of pyrazine nitrogen in C₄N quantum dots activating the conjugated structure of the whole complex skeleton and thus promoting the migration and separation of photogenerated charge carriers. More importantly, the obtained C₄NQDs/C₃N₄NSs assembly shows high stability even after 6 recycles, indicating its potential for applications in the field of energy. This work provides an effective synthesis strategy for organic homogeneous structure assembly with high photocatalytic performance.