In-Situ Growing of MIL88A(Fe)@Active Faceted Cu2O Core-Shell Heterostructure for Super Photocatalytic Performance and Catalytic Reduction of Toxic Nitrophenol Compounds

Herein, well-constructed 2D active (110) and (111) faceted Cu₂O nanosheets are in-situ grown on the surface of spindle MIL-88A to form a novel porous MIL88A (Fe)@active faceted Cu₂O core-shell heterostructure via a facile solvothermal method. The fabricated heterostructure is optimized to be a promising catalyst for the catalytic reduction of various nitrophenol compounds such as P-nitrophenol and 2,4-dinitrophenols, as well as the removal of methylene blue dye (MB). The optimal M88@Cu₂O-2 heterostructure demonstrated an outstanding catalytic performance for reducing nitrophenols, reaching 96.7% for P-nitrophenol and 96.1% for 2.4-dinitrophenol. It also achieved excellent photocatalytic activity for MB dye, reaching 95% through 30 min, compared to 64% and 72% for Cu₂O and MIL-88A, with rate constants (k) reaching 0.1, 0.038, and 0.04 min^-1, respectively. The surprising photocatalytic performance of the prepared structure could be attributed to the following aspects: (i) the growth of the active (111) and (110) facets Cu₂O on the surface of MIL-88A, which could provide various surface energies, reactivates, and crystallographic arrangements, all of which impact the photocatalytic efficiency of the designed M88@Cu₂O-2 heterostructure, (ii) the construction of an efficient heterojunction between active faceted Cu₂O and MIL88A, which resists the recombination of e^- and h⁺, improving the migration and separation of charge carriers, and (iii) the core-shell construction could provide more electron transport channels to significantly enhance the suppression of electron-hole pair recombination in the photocatalytic process. Besides that, the M88@Cu₂O-2 core-shell has great photo-electrochemical performance, reaching 17.68 μA/cm² for the photocurrent test and 73 mA/cm² for the LSV test when exposed to visible light. Our study will provide a new vision for developing more hierarchical core/shell MOF-based heterostructures with outstanding multifunctional performance for future industrial practice.