Size Matters: A Comparison of Nanoparticle Catalysts vs. Single Atom Catalysts as Applied to Engineered Systems for Catalytic Oxidation Wastewater Sterilization

Catalytic oxidation processes for engineering advanced wastewater sterilization have been well reported. Despite remarkable advancements, a systematic analysis of metal site dimensions (ranging from nanoscale clusters to single-atom configurations) for wastewater sterilization and their bactericidal properties/mechanisms remains conspicuously absent. This comprehensive review fills this critical void by rigorously examining how metallic site dimensionality governed reactive oxygen species (ROS) production in both photocatalytic and Fenton-like systems for water sterilization. The bactericidal efficacy of catalytic oxidation systems originates from size-mediated electronic configurations and geometric structures at metal active centers. Single-atom catalysts (SACs) achieve superior atomic efficiency in ROS production, while nanoparticle configurations demonstrate favorable cost-stability performance. These structural variations collectively determine microbe-catalyst contact dynamics, reactive oxygen formation, and material longevity under continuous operation, highlighting the necessity for tailored catalyst design strategies. We further culminate in highlighting enduring challenges including economic scalability and practical implementation barriers, while proposing innovative cross-disciplinary solutions incorporating machine learning (ML) methodologies. By establishing direct correlations between metal site architecture and bactericidal efficacy, this work seeks to inform the creation of advanced sustainable water purification technologies.