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

Abstract

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 NH4Cl at different KOH/NH4Cl ratios. Specifically, a high KOH/NH4Cl 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 H2 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.