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 FexAlyNiz-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.