Asymmetric Coordination in Cobalt Single‐Atom Catalysts Enables Fast Charge Dynamics and Hierarchical Active Sites for Two‐Stage Kinetics in Photodegradation of Organic Pollutants

Single-atom catalysts (SACs) have attracted growing interest in solar-driven catalysis, though challenges persist due to symmetrical metal coordination, which results in limited driving force and sluggish charge dynamics. Additionally, uneven energy and mass distribution complicate reaction pathways, ultimately restricting solar energy utilization and catalytic efficiency. Herein, we synthesized cobalt single atoms decorated carbon nitride catalysts featuring a highly asymmetric Co─C₂N₃ coordination, tailored for photocatalytic organic pollutants removal. Advanced experimental studies and simulation results collectively revealed that the unique microenvironment surrounding Co single atoms improved charge dynamics and created reactive hot spots, facilitating the generation of reactive oxygen species during the photocatalytic degradation of organic pollutants. These enhanced charge dynamics, combined with hierarchical active sites, resulted in two-stage reaction kinetics and excellent stability for the degradation of bisphenol A in wastewater, distinctly outperforming the first-stage kinetics observed for polymeric carbon nitride. This work advances the understanding of structure-performance relationships in SAC-based photocatalytic degradation and offers valuable insights for the design of next-generation SACs in environmental catalysis.