Single-atom catalysts (SACs) have been extensively employed for peroxymonosulfate-based advanced oxidation processes (PMS-AOPs), because of the maximum atomic efficiency offered by homogeneous-dispersed metal atoms and facile recyclability attained by the heterogeneous substrate. Intriguingly, though SACs with atomically isolated metal–nitrogen moieties have shown exceptional activities in PMS-AOP-based water treatment, their catalytic performances and mechanisms varied with the structures. In this review, the catalytic mechanisms of SACs/PMS systems were summarized. Specifically, nonradical reactive oxygen species are involved in the majority of the reactions, while singlet oxygenation, electron-transfer, and high-valent metal-oxo species are identified as dominant nonradical pathways. We also discussed the effects of metal center, metal loading, and substrate on the overall catalytic activities and mechanisms in PMS-AOPs. The pivotal roles of coordination environment in modulating the activity of SACs and reaction pathways were highlighted. Furthermore, an outlook on future challenges and prospective for SACs in water purification is presented.

中文翻译：

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用于过一硫酸盐介导的水净化的单原子配位依赖性催化

单原子催化剂（SAC）已广泛用于基于过一硫酸盐的高级氧化过程（PMS-AOP），因为均匀分散的金属原子提供了最大的原子效率，并且非均质基质实现了轻松的可回收性。有趣的是，尽管具有原子隔离的金属氮部分的 SAC 在基于 PMS-AOP 的水处理中表现出优异的活性，但其催化性能和机制因结构而异。本综述总结了 SAC/PMS 系统的催化机制。具体来说，非自由基活性氧参与了大多数反应，而单线态氧化、电子转移和高价金属氧被认为是主要的非自由基途径。我们还讨论了金属中心、金属负载和底物对 PMS-AOP 整体催化活性和机制的影响。强调了协调环境在调节 SAC 活性和反应途径中的关键作用。此外，还对 SAC 在水净化领域的未来挑战和前景进行了展望。