Regulating bulk polymeric carbon nitride (PCN) into nanostructured PCN (NPCN) has long been proved effective to improve its photocatalytic activity, which is applicable to crystalline carbon nitride: potassium poly (heptazine imide) (K-PHI). Currently, simplifying the synthesis of nanostructured K-PHI (NK-PHI) is challenging and has drawn widespread attention. This work demonstrated the one-step concise and sustainable synthesis of NK-PHI by a steam-assisted method. The NK-PHI exhibited a highly boosted visible-light photocatalytic hydrogen evolution activity, which is 38.4, 4.4 and 3.4 times to that of PCN, NPCN and K-PHI. The improvement of photocatalytic activity mainly benefitted from increased active sites and highly facilitated photoinduced charges transfer and separation. Moreover, the sustainability of this approach was proved by recycling the structure-directing agents (KCl) and steam source (Mg(OH)₂) to repeatedly synthesize high-quality NK-PHI.

长期以来，将本体聚合的氮化碳（PCN）调节为纳米结构的PCN（NPCN）可以有效地提高其光催化活性，这适用于结晶氮化碳：聚庚二酰亚胺钾（K-PHI）。当前，简化纳米结构的K-PHI（NK-PHI）的合成是具有挑战性的，并引起了广泛的关注。这项工作证明了通过蒸汽辅助方法一步一步精简和可持续地合成NK-PHI。NK-PHI表现出高度增强的可见光光催化氢释放活性，是PCN，NPCN和K-PHI的38.4、4.4和3.4倍。光催化活性的提高主要得益于活性位点的增加和高度促进的光诱导电荷的转移和分离。而且，₂）反复合成高质量的NK-PHI。