Unveiling the fundamental understanding of two dimensional π-conjugated FeN4+4 sites for boosting peroxymonosulfate activation

The absence of periodic structures and uncertainty concerning active sites in traditional single-atom catalysts (SACs) consistently impede the understanding of the coordination environment and its impact on the peroxymonosulfate (PMS) activation mechanism. In this study, we develop well-defined FeN4+4 active-site configurations featuring robust and ordered N-coordinated Fe single-atomic centers within fully π-conjugated polyphthalocyanine frameworks (CPFs). CPF–FeN4+4 functions as an outstanding PMS activator, exhibiting remarkable efficiency in the degradation of bisphenol A (BPA) with a rate constant of 1.87 min−1, surpassing the majority of state-of-the-art SAC-based PMS systems. Mechanistic scrutiny unveils heightened chemisorption and electron transfer dynamics between PMS and CPF–FeN4+4, facilitating a 1O2-dominated selective oxidation pathway. The distinctive FeN4+4 active sites, integrated into π-conjugated frameworks, expedite S–O bond cleavage in PMS, thereby reducing the energy barrier for the formation of *HSO3 and *O2 (1O2 precursors). The charge redistribution in CPF–FeN4+4 engenders a dual-pump-driven, electron-fast shuttle path, involving electron-rich Fe centers and electron-poor C surrounding adjacent benzene rings, ensuring the continuous production of 1O2. This study not only delineates precise active sites at the atomic level for PMS activation but also advances the evolution of a highly promising catalytic oxidation system tailored for practical environmental purification.