Multidimensional Nanoconfined Catalysts in Advanced Oxidation Processes: Mechanisms, Performance, and Limitations

Water pollution caused by the continuous emergence of organic contaminants poses increasing challenges to conventional treatment technologies. Although advanced oxidation processes (AOPs) based on nanoconfined materials show great promise, their practical application remains constrained by short radical lifetimes, mass transfer limitations, and catalyst deactivation. This review systematically summarizes the critical role of nanoconfinement effects in AOPs. Through size exclusion and electrostatic regulation, confined spaces promote reactant enrichment and interference exclusion, while confined mass transfer and capillary-driven effects accelerate reaction kinetics. Particular emphasis is placed on multidimensional nanoconfined systems, ranging from zero-dimensional to three-dimensional structures and catalytic membranes, and on how structural design improves reaction microenvironments and active-site accessibility. The synergistic integration of confined structures with external fields, such as electric fields, is further discussed, highlighting their ability to regulate the electronic structure of active sites and shift reaction pathways from non-selective radical oxidation to efficient and highly selective non-radical routes. By optimizing parameters such as pH and catalyst-to-oxidant ratio, nanoconfined systems can achieve efficient pollutant degradation under near-neutral conditions while maintaining strong anti-interference capability and stability in real water matrices containing natural organic matter and inorganic ions.