Synthesis of highly crystallized g-C3N4 by regulating staged gaseous intermediates for hydrogen production

Graphitic carbon nitride (g-C 3 N 4 ) attract extensive attentions as an organic semiconductor. However, incomplete polymerization and low crystallinity remain a challenge for synthesizing g-C 3 N 4 with ideal structure and property. Herein the critical roles of gaseous intermediates produced at certain stage to polymerization and crystallization is investigated by venting gaseous intermediates at a fixed heating temperature. The g-C 3 N 4 vented at 230 °C demonstrates superior crystal quality and hydrogen production activity over others, inversely demonstrating the negative influence of these gaseous intermediates on the polymerization and crystallization. Crystal quality and hydrogen production rate decreases gradually when vented at 390 and 550 °C, suggesting the relatively positive effect. Venting the gaseous intermediates unfavorable to polymerization contributes significantly to orderly stacking of the 2D planes, thus greatly boosting the interlayer charge transfer and the hydrogen production rate. This venting strategy clarifies the role of staged gaseous intermediates by simply regulating the calcination process, which is important for synthesizing g-C 3 N 4 with desired microstructure and properties. Graphical abstract