Curvature-strained single-atom cobalt for water purification: Breaking the adsorption-activation trade-off in...

Catalytic ozonation stands as a pivotal solution for water purification by targeting recalcitrant pollutants. Yet, breaking the intrinsic "adsorption-activation" trade-off is critical for advancing catalytic ozonation and remains a formidable challenge due to the rigid electronic structure of conventional catalysts. Herein, a curvature strain engineering strategy is proposed to modulate the intrinsic activity of single-atom Co sites on hollow carbon spheres. By regulating the support curvature, we introduce precise tensile strain onto the Co-N₄ moieties. Theoretical and experimental investigations reveal that although this geometric distortion elongates Co-N bonds, the downshift of the d-band center not only stabilizes the structure by minimizing antibonding orbital filling but also optimizes Co-N/O orbital overlap, establishing a low-resistance hybridization channel. This enables a synergistic "Push-Pull" mechanism: the electron-deficient Co center firmly anchors O₃ and stabilizes surface-adsorbed oxygen species (AOS, *O and *OO) ("Pull"); simultaneously, the curvature-induced charge accumulation drives electrons through the optimized orbital channel to trigger O₃ activation ("Push"). Quantitative analysis unveils that the curvature-dependent enhancement of single-atom Co as strong Lewis acid sites directly boosts O₃ utilization efficiency. Consequently, the high-curvature catalyst exhibits exceptional intrinsic activity for ·OH and AOS generation, significantly outperforming its low-curvature counterparts. Furthermore, this robust atomic structure translates to impressive long-term stability, while the strong anchoring of AOS confers exceptional resistance to environmental interferences. Practical application in real biological effluent demonstrated efficient mineralization and detoxification. This work advances the atomic-level design of robust ozonation catalysts by shifting the paradigm from chemical doping to geometric topological modulation.