Advances and Challenges in the Application of Confined Catalysts in Heterogeneous Advanced Oxidation Processes: A Review

The traditional advanced oxidation processes (AOPs) encounter numerous challenges, including the brevity of free radical lifespan, substantial reagent consumption, and the potential risk of secondary pollution. Furthermore, issues associated with agglomeration, leakage, and deactivation of heterogeneous catalysts cannot be overlooked. As an innovative strategy, confined materials can significantly enhance the efficient and stable degradation of pollutants through mechanisms such as reactant enrichment, enhanced mass transfer, and modulation of molecular structure. In-situ characterization technology, while offering profound insights into the mechanisms underlying confinement effects, faces certain practical constraints. In comparison to non-confined materials, confined materials exhibit obvious advantages in terms of cost-effectiveness. This paper reviews the recent advancements in confined materials utilized within heterogeneous AOPs. Moreover, the efficiency and cost-effectiveness of confined materials across various application systems are systematically analyzed. Additionally, the mechanisms of confinement, including enhanced mass transfer and modifications in molecular structure, are highlighted, along with the critical role of confinement strategies in optimizing the properties of nanomaterials. Finally, this paper summarizes the challenges confronted by confined catalysts in the field of water treatment AOPs and outlines promising avenues for future research endeavors.