Single-Atom Catalysts Originated from Metal-Organic Frameworks for Sulfate Radical-Based Advanced Oxidation Processes: Critical Insights into Mechanisms

The widely discussed single-atom catalysts (SACs) are regarded as a kind of attractive material for sulfate radical-based advanced oxidation processes (SR-AOPs) owing to their maximum atomic utilization efficiency and outstanding stability. Currently, metal-organic frameworks (MOFs) have appeared as prospective precursors for building SACs due to extensive chelating sites, functional adjustability, and structural tunability. However, there are few critical and systematic reviews about the application of MOF-derived SACs in SR-AOPs, especially in-depth analysis of the mechanisms. Therefore, this review seeks to offer a thorough summary of the development of MOF-derived SACs in SR-AOPs. First, the unique advantages of MOFs as derivative precursors for SACs are discussed thoroughly. Afterward, the current synthesis strategies are elaborated categorically to unveil the formation process of single atoms and their coordination environments. Notably, the roles of different reaction sites including the generation of reactive species and mediating electron transfer are further analyzed to explain mechanisms comprehensively. Thereafter, the characterization techniques and theoretical calculations for mechanisms studies are also highlighted. Eventually, critical insights into present challenges and future developments are proposed, which are expected to enhance the catalytic efficiency of MOF-derived SACs in SR-AOPs. This review aims to offer a thorough summary of the development of metal-organic framework-derived single-atom catalysts in sulfate radical-based advanced oxidation processes. The current synthesis strategies are elaborated categorically and the roles of different reaction sites are further analyzed. The related characterization techniques and theoretical calculations for mechanisms studies are also highlighted. Eventually, critical insights into present challenges and perspectives are proposed.image