Unlocking the Potential of Peroxymonosulfate Activation: Rare-Earth-Modulated Cobalt Species in N-Doped Carbon Catalyst for Efficient Organic Pollutant Degradation

The development of efficient catalysts for peroxymonosulfate (PMS) activation remains a pivotal yet formidable challenge in advanced oxidation processes (AOPs). While Co-based catalysts are promising, their performance is often hindered by significant bottlenecks. Herein, we report a strategy of electronic structure engineering via rare-earth europium (Eu) doping to enhance the catalytic performance of Co-N-C substantially. The incorporated Eu³⁺ ions serve a dual function: They act as Lewis acid sites to strengthen the adsorption capacity of PMS and simultaneously function as electron donors to modulate the electronic structure of the Co active centers. Consequently, the optimized catalyst (1:10-Eu₂O₃@Co-N-C-700) exhibits exceptional degradation activity, achieving near-complete RhB removal within 2 min with a high reaction rate constant (<i>k</i>) of 2.393 min^-1─2.2 times greater than that of its undoped counterpart. Furthermore, the catalyst demonstrates excellent mineralization efficiency, stability, and reusability. Mechanistic investigations, corroborated by quenching experiments, reveal that singlet oxygen (¹O₂) is the dominant species in a nonradical degradation pathway, ensuring its robustness in complex aqueous matrices. This work establishes a rare-earth doping paradigm for the rational design of high-performance cobalt-based catalysts.