Single‐Atom Cobalt Species on Curved Hollow Carbon Sphere: Breaking Linear Scaling Relationship Limitations in Electrocatalytic Deactivation of Dilute Antibiotic Pollutants

Despite maximal atomic efficiency, single-atom catalysts (SACs) are constrained by linear scaling relationships in electrocatalytic hydrodechlorination (ECHD), a process effective for antibiotic pollutant deactivation yet challenged by multi-proton /electron transfer and dilute reactant conditions. Herein, a novel cobalt (Co)-SACs consisting of single-atom Co anchored on a nitrogen-doped hollow porous carbon sphere (Co₁/N-HCS) is fabricated, which exhibits a remarkable mass activity of 14.1 g_FLO g_Co ^-1 at -0.30 V toward florfenicol (FLO, a typical antibiotic pollutant), outperforming Co₁/carbon black, Co nanoparticles/carbon black, and previously reported catalysts. Mechanistic studies reveal that the unique hollow porous architecture of N-HCS facilitates fluid dynamic enhancement and localized adsorptive enrichment of dilute FLO, while its curved surface boosts proton transfer at Co₁ through localized electric field enhancement. The dual enhancements enable Co₁ to break the linear scaling relationship limitations. Field tests for Co₁/N-HCS in natural lake water demonstrate excellent environmental stability and matrix interference resistance. Furthermore, it could effectively deactivate dilute FLO (5 µmol L^-1) while suppressing the emergence of antibiotic resistance gene, highlighting its prospect in antibiotic pollution remediation. This study introduces a paradigm-shifting support architecture to transcend the SACs performance boundary, while pioneering the application of ECHD for antibiotic pollutant remediation.