Precise construction of carbon/nitrogen dual-defects synergizing with Co single-atoms for enhanced Fenton-like degradation of emerging contaminants

Introducing nitrogen or carbon defects (V N or V C ) in g-C 3 N 4 improves the electronic properties of metal active sites, enhancing Fenton-like catalytic efficiency. However, the combined introduction of V N and V C are rarely studied, and understanding their synergistic effects is important. Herein, this study proposes a precise synthesis strategy by combining Co single atom active centers with graphitic carbon nitride containing carbon/nitrogen double defects (V C, N ) to obtain Co-V C, N /CN-2 catalyst. This catalyst can efficiently activate peroxymonosulfate (PMS) to degrade paracetamol (PCM), achieving nearly 100 % non-radical degradation pathway. Moreover, the V C, N of Co-V C, N /CN-2 can regulate the electron density around Co atoms, optimizing charge separation and migration. Based on a series of experiments and density functional theory (DFT) calculations, it has been confirmed that there is a strong synergistic effect between Co single atom reaction sites and V C, N and the introduction of double defects can enhance photocatalytic efficiency, with a degradation rate exceeding 85 % in 15 cycles. This research offers a scalable method for creating stable single-atom catalysts and insights into electronic structure-mediated non-radical catalysis, advancing high-efficiency water purification system design.