Nanoconfined Catalysts for Persulfate‐Based Fenton‐Like Oxidation: Mechanisms, Selectivity, and Environmental Applications

Persulfate (PS)-based Fenton-like advanced oxidation processes (AOPs) have emerged as promising strategies for the degradation of emerging pollutants. Nevertheless, their practical deployment remains hindered by low PS utilization efficiency, poorly controlled generation of reactive species, and limited catalyst durability. Nanoconfinement engineering has emerged as a powerful strategy to overcome these limitations by tailoring the catalytic microenvironment at the nanoscale. This review comprehensively summarizes the recent progress of nanoconfined catalysts in PS-based AOPs, including nanoconfined metallic atomic catalyst, metal nanocluster catalyst, metal nanoparticle catalyst, and metal compound catalyst within nanoconfined structures. In addition, the superiorities of these nanoconfined architectures that enhance catalytic performance are analyzed thoroughly in terms of active site dispersion, reaction dynamics, electronic structure, reaction selectivity, and catalyst stability to provide a deeper mechanistic understanding of confinement-induced catalytic behaviors. Importantly, the reasons why nanoconfinement enables selective regulation of radical and non-radical pathways for improving oxidation selectivity and robustness in complex water matrices are also summarized. Despite significant advances, challenges remained in precise structure control, mechanistic understanding, and large-scale implementation are proposed. This review highlights forward-looking perspectives on the rational design and application of nanoconfined catalysts in PS-based Fenton-like AOPs, providing guidance for future advancements in sustainable water treatment.