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

Graphitic carbon nitride (g-C3N4) has been demonstrated to be a rising star among semiconductor materials for photocatalytic hydrogen (H-2) production. However, pristine g-C3N4 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 ->pi* 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 H2 generation performance (9523.7 mu molg(-1)h(-1)) under visible- light (lambda > 420 nm) irradiation, which was about 20 times that of unmodified g-C3N4 (458 mu mol(-1)h(-1)).