Construction of MOF-on-MOF Heterojunctions for the Highly Efficient Catalytic Nitroarene Hydrogenation under Mild Conditions

Precise modulation of the electronic structure of the catalyst is critical for generating highly active sites in targeted catalytic transformations. We report a strategy to regulate the electronic properties of metal-organic frameworks (MOFs) by constructing functional-group-modified MOF-on-MOF heterojunctions for selective nitroarene hydrogenation. As a representative heterostructure, the ZIF-67-on-NH₂-UiO-66 heterostructure is fabricated by epitaxially growing Co-based ZIF-67 on NH₂-UiO-66. Combining experimental studies and first-principles calculations demonstrates that the electron-donating substituent (-NH₂) group elevates the d-band center of the heterojunction, facilitating electron transfer compared to the unfunctionalized ZIF-67-on-UiO-66 analog. Consequently, ZIF-67-on-NH₂-UiO-66 exhibits exceptional reactivity and chemoselectivity for hydrogenating diverse functionalized nitroarenes under mild conditions, surpassing most reported catalysts under comparable settings. This work establishes ZIF-on-MOF functionalization as an effective strategy to engineer electronic structures at catalytic interfaces for advanced selective hydrogenations.