Polymeric carbon nitride (PCN) is a metal‐free semiconductor that has received extensive research attention due to its unique advantages such as low cost, high stability, and visible‐light response. However, pristine PCN is not an ideal photocatalyst because of fast electron–hole recombination and its inert surface for molecular adsorption. Nevertheless, benefiting from the N‐linked tri‐s‐triazine structure, PCN can be readily functionalized through chemical modifications. As such, researchers have made enormous efforts to develop various strategies for modifying PCN to achieve enhanced photocatalytic activities. Herein, recent advances in PCN functionalizations with different atomic or molecular units, including metal and nonmetal elements, small functional groups, organic functional fragments, and metal complex motifs, are summarized. Moreover, the effect of different PCN functionalization strategies on the molecular structure, optical properties, electronic behaviors, and photocatalytic activities particularly for water splitting and CO₂ reduction is discussed. In the end, the remaining challenges in the structural modification of PCN and future opportunities of functional PCN‐based photocatalysts for efficient solar fuel production are elaborated on.

中文翻译：

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聚合物碳氮化物在太阳能燃料生产中的原子和分子水平官能化

聚合碳氮化物（PCN）是一种无金属的半导体，由于其独特的优势（例如低成本，高稳定性和可见光响应）而受到了广泛的研究关注。但是，原始PCN并不是理想的光催化剂，因为它具有快速的电子-空穴复合以及其惰性的分子吸附表面。但是，得益于N-连接的三-s-三嗪结构，PCN可以通过化学修饰轻松地功能化。因此，研究人员付出了巨大的努力来开发各种修饰PCN的策略，以实现增强的光催化活性。本文中，总结了具有不同原子或分子单元（包括金属和非金属元素，小官能团，有机功能片段和金属配合物基序）的PCN功能化的最新进展。此外，讨论₂减少。最后，阐述了PCN的结构改造中仍然存在的挑战，以及基于功能性PCN的光催化剂在高效生产太阳能方面的未来机会。