Search

This work presented a dry ball milling combined with subsequent pyrolysis strategy to prepare soybean residue nanocarbon anchored dual-site catalysts (Fe-NC-900) with Fe single atoms and ultra-small clusters for the efficient catalytic oxidation of RhB by activated PMS. Particularly, the 1O 2 oxidation was the main non-radical pathway rather than the high-valent iron oxidation and electron transfer mechanism, 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 advanced oxidation processes. [Display omitted] • Successful synthesis of catalysts with ultra-small clusters and single-atom sites by a ball milling method combined with subsequent pyrolysis process. • Fe-NC-900 catalysts are highly active and extremely stable for catalytic oxidation of refractory organic compounds. • 1O 2 oxidation is the main non-radical pathway rather than the high-valent iron oxidation and electron transfer mechanism. • The RhB is adsorbed on the pyrrole-N sites via a "donor-acceptor" mechanism. • The single-atom Fe-N x generated is responsible for peroxydisulfate activation. 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 successfully fabricated a catalyst (Fe-NC-900) with single-atom sites and ultra-small clusters by a ball milling method combined with subsequent pyrolysis process. Fe-NC-900 showed high efficiency and superior stability in the activation of peroxymonosulfate (PMS) for catalytic oxidation of refractory organic compounds. Chemical quenching experiments, electron paramagnetic resonance (EPR), in-situ Raman spectra, and electrochemical analysis indicated that the 1O 2 oxidation was the main non-radical pathway rather than the high-valent iron oxidation and electron transfer mechanism for the degradation of RhB in the Fe-NC-900/PMS system. This work provides useful insights into the design and synthesis of the catalysts with single atoms and ultra-small clusters for practical applications in Fenton-like catalytic processes. [ABSTRACT FROM AUTHOR]