A graphitic carbon nitride metal-free visible light photocatalyst with controllable carbon self-doping towards efficient hydrogen evolution

Controlling molecular defects via element doping is an effective strategy for tailoring electronic structures and charge separation in photocatalysts. However, the rational design of self-doped catalysts is generally confronted with the need for expensive reagents, high dopant ratios and environmentally unfriendly materials. Herein, carbon self-doped graphitic carbon nitride (DCN-x) is obtained via one-pot thermal polymerization of urea and d-mannitol. The sp(2)-hybridized nitrogen atoms are partially substituted by carbon atoms from dopants. The corresponding defects provide the photocatalyst with extended light harvesting up to 600 nm, a tunable optical bandgap, and the formation of more delocalized electrons with a uniform distribution at the defect scope of a C-C bond. In addition, increased band-tail states are found in DCN-3, which greatly enhance charge separation. A high photocatalytic hydrogen evolution rate of 3180 mu mol g(-1) h(-1) is achieved under visible light irradiation (lambda > 420 nm), which is about 5.3 fold higher than that of pristine g-C3N4. This work provides a green and economical method to synthesize g-C3N4 with controllable carbon self-doping sites for efficient energy conversion related applications.

Automated summary

Controlling molecular defects through element doping is an effective strategy for tailoring electronic structures and charge separation in photocatalysts. In this study, carbon self-doped graphitic carbon nitride was successfully synthesized, which showed extended light harvesting, tunable optical bandgap, and enhanced charge separation for high photocatalytic hydrogen evolution. This green and economical method provides a promising approach for efficient energy conversion applications.