Calcium-Based Bifunctional Lewis Acid-Base Sites Induce the Directional Generation of Radical in Catalytic Ozonation

Reactive oxygen species (ROS) mediate critical redox processes in contaminant degradation, precise regulation of radical speciation remains fundamentally constrained by the heterogeneity in active site configurations and coordination microenvironments. Here, a site-specific engineering strategy is demonstrated through spatially organized Ca─O basic sites and Ca─O─Si acidic centers, fabricated via Ca²⁺-mediated cross-linking of sodium alginate. Mechanistic studies reveal that the alkaline Ca─O domains enhance spin density of *OO intermediates to promote hydroxyl radical (·OH) generation, while adjacent acidic Ca─O─Si moieties simultaneously lower *O formation energy barrier and suppress *OO conversion, establishing a selective radical generation pathway. This bifunctional design achieves near-complete removal (>99.9%) of recalcitrant pollutants including oxalic acid and atrazine within 30 min, demonstrating 3-230-fold rate enhancement over conventional advanced oxidation processes (AOPs). The engineered catalyst maintains stable efficiency over 20 cycles in actual wastewater treatment processes, providing a molecular-scale blueprint for directional ROS manipulation in water treatment.