Confined conductive and light-adsorbed network in metal organic frameworks (MIL-88B(Fe)) with enhanced photo-Fenton catalytic activity for sulfamethoxazole degradation

High light adsorption and fast charge separation are crucial for photo-Fenton catalytic activity of MOFs. Herein, bottom-up design was proposed to fabricate polypyrrole (PPyC) nanowires in MIL-88B(Fe) cages as photo-Fenton catalyst for Sulfamethoxazole (SMX) efficient degradation. Pyrrole was prior anchored into MIL-88B(Fe) cluster via Fe-N coordination, and then the additional monomer pyrrole was further triggered bottom-up polymerization in confined cages of MIL-88B(Fe) and formed PPyC@Py-MIL(Fe) composite. These PPyC nanowires were dispersed in Py-MIL(Fe) cages and tightly connected with MOFs clusters via Fe-N bonding. Characterization proved that: (1) Interfacial Fe-N can significantly promote the efficient electron transport from PPyC nanowires to Py-MIL(Fe), enhance optical absorption property, and construct strong Lewis acidic sites and ligand vacancies in PPyC@Py-MIL(Fe). (2) The confined PPyC nanowire via Fe-N connection remarkably promote photo-generated electron-hole separation, Fe2+|Fe3+ redox ability of MOF, and improved photo-electric corrosion ability. As a result, it significantly enhanced the photo-Fenton catalytic performance for SMX degradation. Catalytic oxidation was attributed to the generation of ‧OH species that oxidized 93% SMX in 60 min, showing ultra-rapid degradation and TOC removal rates of 33.7 min−1·mg·g−1 and 8.68 min−1·mg·g−1 respectively, which was about 4–220 times higher than those reported state-of-the-art catalysts. Additionally, the PPyC@Py-MIL(Fe) catalyst showed minimal loss in catalytic activity even after recycling for 10 times, exhibiting good recycling stability compared to many MOFs. Systematic analysis shown that in-situ anchored growth of polypyrrole in confined porous cages of MOF can effectively enhance the catalytic activity and stability of MIL-88B(Fe), and has great development potential applications for photo-Fenton catalytic degradation of organic pollutants.