Discriminative Peroxymonosulfate Activation on Iron Carbides for Redox-Neutral Singlet Oxygen Generation

In conventional redox cycle-based Fenton-like processes, the imbalanced rates between the reductive activation of peroxymonosulfate (PMS) and the subsequent catalyst recovery by PMS oxidation often leads to the catalyst deactivation, posing a major challenge to achieving long-term stability. Herein, we report a discriminative, redox-neutral PMS activation pathway enabled by a core-shell Fe₃C@C catalyst, which eliminates performance loss caused by such redox imbalance. Covalent Fe─C bonds within Fe₃C@C suppress complete electron transfer for PMS oxidation or reduction, preventing the radical-forming pathways. Instead, PMS is activated through electronic induction, discriminatively cleaving the peroxyl O─O bond to generate singlet oxygen (¹O₂) as the sole reactive oxygen species (ROS) without significant changes in the Fe valence state, thereby greatly enhancing catalyst durability. Beyond PMS activation, the highly conductive Fe₃C@C network serves as an efficient electron relay, promoting pollutant degradation with ¹O₂ by facilitating electron-exchange between PMS and pollutant. By integrating redox-neutral PMS activation with electron-connection driven pollutant oxidation, Fe₃C@C achieves both high reactivity and exceptional long-term stability, overcoming the traditional trade-off between activity and durability. This work introduces a new paradigm in Fenton-like catalysis, demonstrating how covalent coordination engineering can unlock selective, nonradical pathways for sustainable and robust water treatment.