Trimetallic carbon-based catalysts derived from metal-organic frameworks for electro-Fenton removal of aqueous pesticides

Abstract

Pesticide overuse has posed a threat to agricultural community as well as aquatic animals. Heterogeneous electro-Fenton (HEF) processes have received considerable attention for aqueous contaminants removal, and metal-organic frameworks (MOFs) serve as promising templates for fabrication of carbon-based HEF catalysts with low Fe leaching and enhanced stability. Herein, multimetallic MOF-derived HEF catalysts CMOFs@PCM have been demonstrated as efficient and stable HEF catalysts for aqueous pesticide degradation and mineralization. The porous carbon monolith (PCM) substrate effectively catalyzed 2-electron oxygen reduction reaction (ORR) over the pH range of 4–10 to in situ generate H₂O₂, which was then activated by the anchored Fe₃O₄, Fe₃C and NiO into OH for pesticide degradation. Fe₈Al₇Ni₅-CMOF@PCM achieved over 90% napropamide degradation within 60 min in the pH range of 4–10, and 96% degradation at neutral condition, 39% higher than monometallic CMIL-88(Fe)@PCM. Meanwhile, the embedded NiO and γ-Al2O₃ showed synergistic effect in promoting the catalytic activity of Fe sites, resulting in substantially enhanced performance of trimetallic Fe_xAl_yNi_z-CMOF@PCM compared to the monometallic counterparts. On the other hand, the unique core-shell structure and Fe₃C interlayer formed by co-pyrolyzing Fe-containing MOFs-NH₂ with PCM greatly minimized the metal leaching and enhanced the stability of the electrocatalysts.

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