Single-atom catalysts (SACs) with M-N₄ structure have drawn significant attention due to the facile preparation, maximum atom efficiency, unique electronic properties, uniform active sites, and excellent activity. Such catalysts integrated the merits of traditional homogeneous and heterogeneous catalysts effectively solve the cost, activity, and reuse problems. More importantly, the M-N₄ structure is flexible and other species like atoms, groups, and particles can be added to precisely control the local environment of M-N₄ to further improve the catalytic performance. Although unprecedented progress has been made, it remains difficulties in the rational design and controllable synthesis of a suitable SAC for a certain application. This review introduces the progress of M-N₄ catalysts and summarizes the strategies to modulate the M-N₄ structure, including changing the coordination number, tailoring the coordination structure, coordinating with groups, creating dual-atom catalysts (DACs), and coexisting of SAC with DAC and cluster. Special emphasis is placed on the preparation, structure characterization, and reaction mechanism of M-N₄-derived catalysts. Finally, the current challenges of these catalysts are also discussed to provide guidelines for the future design of efficient catalysts.

_{具有MN 4}结构的单原子催化剂(SACs)由于制备简单、原子效率最高、独特的电子性质、均匀的活性位点和优异的活性而备受关注。该类催化剂综合了传统均相和非均相催化剂的优点，有效解决了成本、活性和再利用等问题。更重要的是，MN ₄结构灵活，可以添加原子、基团、粒子等其他物种，精确控制MN _{4的局部环境}进一步提高催化性能。尽管取得了前所未有的进展，但在针对特定应用合理设计和可控合成合适的SAC方面仍然存在困难。_{本综述介绍了MN 4}催化剂的研究进展，总结了调节MN ₄结构的策略，包括改变配位数、剪裁配位结构、与基团配位、创建双原子催化剂（DAC）以及SAC与DAC共存和集群。特别强调MN _{4的制备、结构表征和反应机理}-衍生的催化剂。最后，还讨论了这些催化剂目前面临的挑战，为未来高效催化剂的设计提供指导。