Peroxydisulfate activation by atomically-dispersed Fe-Nx on N-doped carbon: Mechanism of singlet oxygen evolution for nonradical degradation of aqueous contaminants

Single-atom catalysts have drawn increasing attention in advanced oxidation due to their unique structure and significant promise in heterogeneous catalysis. Herein, single-atom iron anchored on nitrogen-doped carbon (SAFe-N-C) was synthesized with iron phthalocyanine (FePc) and metal-organic framework (ZIF-8). With thermal treatment and acid leaching, atomically-dispersed Fe-Nx sites were successfully formed on the surface of N-C support derived from ZIF-8. The prepared catalyst was demonstrated to activate peroxydisulfate (PDS) for chloramphenicol (CAP) degradation. Compared with N-C, the SAFe-N-C shows 6 times enhanced removal efficiency (from 15.3% to 93.1%) for CAP. Moreover, the catalyst shows high catalytic activity in a wide pH range of 5 to 9 and good resistance to inorganic anions, in which a singlet oxygen-dominated process is found. This study reveals the role of single-atom site in singlet oxygen evolution and offers a new catalytic approach for selective removal of organic pollutants in complex water matrix.