One-step fabrication of crystalline carbon nitride with tunable in-plane/interlayer crystallinity for enhanced photocatalytic hydrogen evolution

Improving the crystallinity of polymeric carbon nitride has been proved highly efficient for advanced photocatalysis . Nevertheless, controllable tuning the in-plane and interlayer crystallinity of crystalline carbon nitride has not been realized and their specific effect on photocatalysis is not clear yet. Herein, we proposed a facile one-step approach to selectively fabricate the in-plane or interlayer ordered crystalline carbon nitride by calcining melamine with KOH and NH 4 Cl at different KOH/NH 4 Cl ratios. Specifically, a high KOH/NH 4 Cl ratio results in sample with a highly in-plane integrity while a low ratio leads to a more orderly interlayer stacking. All the crystalline carbon nitride samples exhibit significantly boosted photocatalytic H 2 evolution reaction rate as compared to polymeric carbon nitride, suggesting the positive contribution of enhanced crystallinity to photocatalytic activity. More importantly, the as-prepared sample with a highly in-plane integrity surpasses another sample with a more orderly interlayer stacking in photocatalytic performance, benefitting from its highly in-plane ordered structure, which extends light-harvesting range and promotes exciton dissociation. This work provides a platform to investigate the structure activity relationship between crystallinity and photocatalytic properties of crystalline carbon nitride.