Enhanced n→π* electron transition of porous P-doped g-C3N4 nanosheets for improved photocatalytic H2 evolution performance

Graphitic carbon nitride (g-C 3 N 4 ) has been demonstrated to be a rising star among semiconductor materials for photocatalytic hydrogen (H 2 ) production. However, pristine g-C 3 N 4 usually suffers from inferior activity due to the inadequate visible light harvesting capacity and quick charge recombination. Herein, porous P doped g-C 3 N 4 nanosheets (PCNNSs) were fabricated via a simple thermal condensation of adenosine phosphate and urea followed by thermal exfoliation method. The synergetic effect of the porous structure and P dopant can provide abundant active sites for the photocatalytic reaction, which can enhance light absorption range extending from 450 nm to 700 nm attributed to the n→π* electronic transition, and improve hydrophilicity for easier water molecules adsorption via introducing hydroxyl groups. Furthermore, impurity level caused by the P dopant would change the excitation process and accelerate the charge separation efficiency. Therefore, the PCNNSs exhibited significantly elevated photocatalytic H 2 generation performance (9523.7 μmolg -1 h -1 ) under visible-light (λ > 420 nm) irradiation, which was about 20 times that of unmodified g-C 3 N 4 (458 μmol -1 h -1 ).