A Highly Efficient Catalyst for Fenton-Like Reactions Derived from Bimetallic-Doped Zeolitic Imidazolate Frameworks

Heterogeneous Fenton-like reactions (HTFR) have obtained significant attention for their high efficiency in pollutant degradation. However, developing effective strategies to enhance their performance continues to be a persistent issue. Herein, we synthesized a bimetallic Fe/La-co-doped HTFR catalyst (FeLa-NC) containing Fe3C which was capsulated in the dodecahedral structure of zeolitic imidazolate frameworks. The X-ray absorption fine structure spectroscopy tests indicated that FeLa-NC exhibited two characteristic peaks at approximately 1.47 Å and 2.11 Å, which were assigned to the Fe-C and Fe-Fe coordination shells, respectively. The incorporation of Fe and La not only promoted the formation of a reactive component of nanoscale-encapsulated Fe3C but also induced the complete volatilization of Zn, resulting in a hierarchical porous structure with significantly enhanced specific surface area. Consequently, the prepared FeLa-NC induced a kinetic favorable peroxymonosulfate (PMS) decomposition process during which the activation energy decreased from 40.23 to 10.06 kJ/mol, subsequently, 93.5% degradation efficiency of tetracycline (TC) within 60 min was achieved. The bimetallic modification strategy significantly enhanced the direct electron transfer capability which was verified by the galvanic oxidation process test. O2•-, 1O2, and high-valent metal-oxo species as the primary generated reactive species were identified by quenching experiments and electron paramagnetic resonance tests. Ecotoxicity analysis confirmed the low environmental risk of the degradation intermediates. This work elucidates the bimetallic synergy mechanism in PMS activation and provides a practical design strategy for developing high-performance MOF-derived catalysts for HTFR.