Breaking scaling relationship limitations in peroxymonosulfate activation through electronegativity-driven Fe–Mn dual-metal synergy

Dual-atom catalysts (DACs) driven by peroxymonosulfate (PMS) activation have demonstrated significant potential for addressing the inherent scaling relationship limitation of reaction intermediates, but in-depth mechanistic insight into synergistic interactions between dual-metal sites remains elusive. The Fe-Mn DAC has been designed with the largest electronegativity difference among Fe-based metal pairs to enhance electron transfer and synergistic interactions. The Fe-Mn DAC exhibits exceptional catalytic performance for bisphenol A (BPA) degradation, achieving a reaction rate constant (k_obs) of 1.36 min^-1, and a turnover frequency to PMS concentration ratio of 34.0 L min^-1 g^-2, which significantly surpasses the performance of reported state-of-the-art DACs, SACs, and nanocatalysts. The log k_obs value correlated well with the σ⁺ value (R² = 0.80), indicating that the Fe-Mn DAC readily targets pollutants with strong electron-donating abilities. Besides, ¹O₂ plays a key role in the Fe-Mn DAC/PMS system for BPA degradation. Based on density functional theory calculations, Fe and Mn active sites with a large electronegativity difference effectively enhance the synergistic interactions and decouple the activation and stabilization of reaction intermediates to address the inherent scaling relationship limitation. This study provides a robust framework for the rational design of DACs to enable efficient and sustainable water treatment.