Carbon Self-Doping Induced Activation of n–π* Electronic Transitions of g-C3N4 Nanosheets for Efficient Photocatalytic H2 Evolution

Graphical Carbon self-doped g-C 3 N 4 nanosheets were synthesized in a simple way by a one-step calcination of a ternary supramolecular network of cyanuric acid, ethylene glycol (EG), and melamine. Carbon doping resulted in a distorted framework and induced the activation of n–π* electronic transitions of the C-g-C 3 N 4 nanosheets. The obtained C-g-C 3 N 4 displayed high activity for photocatalytic H 2 evolution owing to the extended light harvesting and faster separation of photogenerated electrons and holes. This paper reports a facile one-pot synthesis strategy to prepare carbon self-doped g-C 3 N 4 (C-g-C 3 N 4 ) nanosheets by using supramolecular networks consisting of cyanuric acid, ethylene glycol (EG), and melamine (CEM) bonded through hydrogen bonding as the thermal polycondensation precursor, in which EG serves as a solvent for cyanuric acid and melamine, and as a source of the doped carbon simultaneously. The threedimensional structure of CEM resulted in the distortion of C-g-C 3 N 4 , which is capable of motivating the n–π* electronic transition involving the N lone pairs to give an additional absorption region from 450 to 600 nm. The hydrogen evolution rate of C-g-C 3 N 4 reaches 73.09 μmol h −1 , which is about 15 times of that over the g-C 3 N 4 obtained from direct thermal polycondensation of melamine owing to its extended light harvesting and faster separation of photogenerated electrons and holes.