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

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.