Degradation of levofloxacin by activation of monopersulfate over energetic MOF-based monatomic Fe catalysts: Bubble formation and degradation mechanism

s Single-atom Fe catalysts are attractive for antibiotic removal via peroxymonosulfate (PMS) activation, with support design being crucial. The metal triazolate framework (hereafter MET) serves as an ideal template due to extremely high theoretical nitrogen content; however, the changes in physicochemical properties and reaction mechanisms during its thermal activation remain unclear. In this work, Fe@C-X catalysts were synthesized by pyrolyzing Fe@MET-6. Characterization revealed that the material features Fe N 4 coordination structure and “bubble-like” hierarchical pores formed during pyrolysis play a key role in enhancing catalytic performance. These structures not only increase specific surface area and pore volume, but also anchor dense Fe N 4 sites and facilitate efficient electron transfer. Consequently, Fe@C-700/800 exhibited rate constants of 0.1152 and 0.2766 min −1 for LEV degradation, respectively, an order of magnitude higher than Fe@C-600 (0.0105 min −1 ). Mechanistic studies indicated that the “bubble”, induced structural optimization governs the PMS activation pathway: the Fe@C-600/PMS system relies on a singlet oxygen ( 1 O 2 ) mechanism, while Fe@C-700/800 with developed conductive networks follow an electron-transfer-dominated route. Additionally, the Fe@C-700 with high LEV degradation and energy-efficiency demonstrated excellent recyclability, strong potential for practical applications and reduced toxicity of degradation intermediates. This study provides new insights into designing efficient single-atom catalysts by regulating MOF-derived architectures.