Iron Single Atoms and Clusters Anchored on Natural N-Doped Nanocarbon with Dual Reaction Sites as Superior Fenton-Like Catalysts

Ultra-small metal clusters have emerged as one of the most promising alternatives to heterogeneous Fenton-like catalysts. Despite the high atom utilization and structural stability of catalysts with ultra-small clusters and single-atom sites, there is still challenging for the synthesis of these catalysts due to their facile aggregation. Herein, we designed and successfully fabricated a catalyst (Fe-NC-900) with single atoms and ultra-small clusters by a ball milling method, which showed highly efficient in catalytic oxidation of refractory organic compounds by activation of peroxymonosulfate (PMS). Combined with chemical quenching experiments and electron spin resonance (ESR), which showed that the degradation of RhB in the Fe-NC-900/PMS system was dominated by the non-radical pathway. Particularly, the 1 O 2 oxidation and electron transfer mechanism were the main non-radical pathway rather than the high-valent iron oxidation, and PMS formed non-radical PMS* intermediates upon activation at the Fe-N x sites, while RhB adsorbed to the pyrrole-N site via a "donor-acceptor complex" mechanism. Benefiting from this system, the Fe-NC-900 exhibited superior activity and stability during the oxidation process. This work provides useful insights into the design and synthesis of catalysts with single atoms and ultra-small clusters for practical applications in catalytic Fenton-like processes