High-yield and crystalline graphitic carbon nitride photocatalyst: One-step sodium acetate-mediated synthesis and improved hydrogen-evolution performance.

To avoid the drawbacks (such as multi-step operations and causing big quality loss) of currently reported molten salt-assisted strategy for the preparation of crystalline graphitic carbon nitride (g-CN) photocatalysts, in this study, an innovative and one-step sodium acetate (CHCOONa)-mediated synthesis strategy has been designed to synthesize a high-yield and crystalline g-CN photocatalyst. It is found that CHCOONa can strongly combine with dicyandiamide (DCDA) to availably prevent the massive sublimation of DCDA and the following intermediates, causing the high-efficiency transformation of DCDA into g-CN with a high yield (52.2 wt%). In addition to the promoted denitrification and quick polymerization of DCDA via CHCOONa, the produced NaCO from CHCOONa decomposition at a higher temperature can further accelerate the polymerization reaction of 3-s-triazine units, leading to the final production of highly ordered and crystalline g-CN. Consequently, the resultant high-yield and crystalline g-CN shows an obviously strengthened hydrogen (H)-evolution rate, about 2.4 times higher than that of bulk g-CN, which is due to the synergetic function of highly crystalline structure, reduced band gap and cyano-groups. The current one-step CHCOONa-mediated synthesis strategy may open a novel horizon for the facile preparations and various applications of crystalline g-CN materials.