Electronic structure reconstruction of Fe-Mn diatomic pair for disentangling activity-stability tradeoff in Fenton-like reactions

Enhanced catalytic activity is often accompanied with loss of selectivity or stability. Herein, we develop the Fe-Mn diatomic catalysts (Fe-Mn DACs) with FeMnN₆ moiety supported on N-doped carbon, which retain the high selectivity of single atom catalysts (SACs) and offer boosted activity and stability due to cooperative interaction between neighboring Fe and Mn atoms. Fe-Mn DACs achieve 100 % 2-chlorophenol (2-CP) degradation in 5 min and near 100 % selectivity for high-valent metal-oxo (HVMO) generation with 100 % peroxymonosulfate (PMS) utilization efficiency, outperforming the counterpart SACs and previously reported Fe/Mn-based catalysts. Multiple experiments demonstrate introducing Fe into the Mn SACs enhances the catalytic activity of Mn sites by boosting the generation of Mn(IV)=O. Theoretical calculations combined with experiments unveil that band gap narrowing and electronic structure optimization triggered by Fe-Mn interaction strengthen orbital overlap and electron transfer between Fe-Mn DACs and PMS, thus promoting PMS adsorption, activation, and HVMO generation. Rapid and sustainable generation of a stable heteronuclear Fe(V)-O-O-Mn(IV) species simultaneously achieves pollutant degradation with high activity, selectivity, and stability to favor water decontamination application. This work offers an atomic-level insight into the synergistic interplay on Fe-Mn diatomic sites in Fenton-like reactions, with promising implications for green environmental remediation.