Constructing peroxydisulfate selective N-doped carbon catalyst via copolymerization strategy for removal of organic contaminants

Nitrogen-doped carbon catalysts have shown high efficiency in activating both peroxydisulfate (PS) and peroxymonosulfate (PMS), making them well-suited for the removal of organic pollutants. In this study, we presented the fabrication of N-doped carbon by adopting copolymer strategy, where aniline and pyrrole are used as monomer molecules. As obtained catalyst displayed excellent bisphenol-A (BPA) removal efficiency with PS (∼98%) compared with PMS (60%). The effect of carbonization temperature on the chemical properties of copolymer-derived N-doped carbon (CNC) were studied using X-ray diffraction, X-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller analysis. Batch experiment results revealed that CNC is more catalytic to PS over PMS activation despite holding a decent amount of PMS active graphitic-N sites. This activity difference was attributed to unique graphitic-N configurations in the CNC. Electron spin resonance spectroscopy, scavenging experiments, and electrochemical studies combinedly revealed that no reactive oxygen species were generated in PS/CNC system. Instead, the BPA degradation proceeds via direct electron transfer mechanism. The optimized CNC system demonstrated promising activity for the removal of other frequently encountered phenolic compounds. Ultimately, this study challenges the generalized notion of high graphitic-N sites are always beneficial for high PMS activation capability, which is not applicable for N-doped carbon catalysts involving direct electron transfer process.