Polymeric carbon nitrides (PCNs) are candidates for metal-containing photocatalysts due to the unique conjugated structures. However, the low activity of PCNs due to their complex microstructure and lack of active surface functional groups can be boosted by finely controlling the active heptazine structure and chemical modification. We herein propose a self-assembly strategy to synthesize PCNs with adjustable microstructure and composition, using benzoic acid and melamine as raw materials. Addition of benzoic acid not only controlled morphology, heptazine structure and band structure, but also introduced hydroxyl and carboxyl groups. The introduced polar groups boosted the formation of singlet oxygen and superoxide anion, improving the photocatalytic activity in selective oxidation of benzylamine; the regulation of heptazine units enhanced the separation and mobility of charge carriers, promoting the activity of hydrogen evolution. Our work provides a strategy for the design of metal-free photocatalysts for the selective synthesis of organics and hydrogen production via photocatalysis.

由于独特的共轭结构，聚合碳氮化物（PCN）是含金属光催化剂的候选材料。但是，由于精细控制活性庚嗪的结构和化学修饰，可增强PCN由于其复杂的微结构和缺乏活性表面官能团而导致的低活性。我们在此提出一种自组装策略，以苯甲酸和三聚氰胺为原料合成具有可调节的微观结构和组成的PCN。苯甲酸的加入不仅控制形态，庚嗪结构和能带结构，而且还引入了羟基和羧基。引入的极性基团促进了单线态氧和超氧阴离子的形成，提高了苄胺选择性氧化的光催化活性。庚嗪单元的调节增强了电荷载流子的分离和迁移，促进了析氢活性。我们的工作为无金属光催化剂的设计提供了一种策略，用于通过光催化选择性合成有机物和生产氢气。