Polymeric carbon nitride is a promising candidate for photocatalytic hydrogen evolution but mostly just shows moderate activity because of its inefficient charge separation and sluggish surface reaction kinetics. Phase-based heterostructures, especially crystal-phase heterostructures that are composed of identical compositions with different crystal phases, can endow nanomaterials with promising properties and efficient photocatalysis applications. In this study, a novel crystalline hexagonal-C₃N₄/g-C₃N₄ hetero-phase junction was synthesized using a direct in situ alkali salt template coupled with organic solvents strategy. High hydrophilicity was obtained because of the synergistic effect between alkali salt and organic solvents in the polycondensation process. The greatly increased separation and transfer efficiency of charge carriers and the improved proton absorption in the surface reaction of the photocatalyst were achieved by the constructed phase junctions between the crystalline hexagonal-C₃N₄ and amorphous g-C₃N₄ decorated with numerous hydrophilic groups. Thus, the carbon nitride hetero-phase junction exhibited dramatically enhanced photocatalytic performance in hydrogen evolution and excellent cycling stability under visible light irradiation. This work presents a novel insight into phase engineering based on carbon nitride materials with surface functional modification for an efficient photocatalytic activity.

聚合氮化碳是光催化氢释放的有前途的候选者，但由于其电荷分离效率低和表面反应动力学缓慢，因此大多仅表现出中等活性。基于相的异质结构，尤其是由具有不同晶相的相同组成组成的晶相异质结构，可以赋予纳米材料以希望的性能和有效的光催化应用。在这项研究中，一种新型的晶体六角C ₃ N ₄ / gC ₃ N ₄使用直接原位碱金属盐模板结合有机溶剂策略合成了异相连接。由于碱盐和有机溶剂在缩聚过程中的协同作用，因此获得了很高的亲水性。通过在晶体六方C ₃ N ₄和非晶gC ₃ N ₄之间建立相连接，可以大大提高电荷载流子的分离和转移效率，并改善光催化剂在表面反应中的质子吸收。装饰有许多亲水基团。因此，氮化碳异相结在氢释放中表现出显着增强的光催化性能，并且在可见光照射下表现出优异的循环稳定性。这项工作为基于具有有效功能光催化活性的表面功能改性的氮化碳材料的相工程提出了新的见解。