N,O co-doped carbon quantum dots nano-island anchored cobalt single-atom catalysts for efficient peroxymonosulfate activation

A novel Co SA-N,O-CQDs/g-C 3 N 4 (CoCCN) single-atom nano-island is synthesized for PMS activation. • 1 O 2 is identified as the dominant reactive species responsible for pollutant degradation. • DFT calculations elucidated that the N,O-CQD optimize charge transfer, reducing the energy barrier for 1 O 2 generation. The persistent contamination of aquatic ecosystems by antibiotic pollutants such as tetracycline hydrochloride (TCH) necessitates advanced oxidation processes (AOPs) for effective remediation. Peroxymonosulfate (PMS)-based AOPs offer high oxidation potential but face challenges in catalyst design, such as the conflict between catalytic activity and durability, as well as metal leaching. Herein, we developed a novel single-atom nano-island (SANI) catalyst composed of cobalt single atoms anchored on N,O co-doped carbon quantum dots (N,O-CQDs) nano-islands supported on g-C 3 N 4 , denoted as CoCCN. This configuration utilizes robust interactions between metal and support to simultaneously boost durability and facilitate PMS activation. The CoCCN catalyst achieved 98.3% TCH degradation within 40 min, with a kinetic constant (k obs  = 0.0873 min −1 ) 2.66-fold higher than that of CoCN/PMS and 15.9-fold higher than CN/PMS. Mechanistic exploration uncovered that singlet oxygen ( 1 O 2 ) is the dominant reactive species responsible for pollutant degradation. Density functional theory (DFT) calculations further elucidated that the N,O-CQD nano-islands optimize charge transfer, reducing the energy barrier for 1 O 2 generation. The catalyst maintained 94.1% efficiency over ten cycles with minimal cobalt leaching, highlighting its robustness across a pH range of 3–10. This work provides a synergistic strategy to overcome activity-stability conflicts in single-atom catalysts for environmental applications. Download: Download high-res image (162KB) Download: Download full-size image