Photocatalytic Reduction of Nitroaromatics over a Cu-MOF/MoS2 Heterojunction via an Indirect Coupling Pathway

Photocatalytic reduction of nitroaromatics to amines is an attractive sustainable alternative to conventional hydrogenation. However, the commonly proposed sequential reduction pathway, involving multiple nitrogen-containing intermediates, can suffer from competing reaction routes and limited control over intermediate conversion, compromising chemoselectivity. Here we construct a face-to-face S-scheme heterojunction by integrating two-dimensional MoS2 nanosheets with a Cu-NTCDA metal–organic framework (CNM) to regulate the reduction pathway. The interfacial electric field promotes charge separation and migration, while the porous MOF enhances substrate enrichment. The optimized CNM1/Mo1 photocatalyst achieves high conversion and excellent stability under 425 nm LED irradiation, with broad functional-group tolerance and negligible dehalogenation of C–X (X = F, Cl, Br, I) bonds. In situ FTIR spectroscopy reveals an indirect coupling pathway involving an azobenzene intermediate that directs amine formation. This work demonstrates the potential of interfacial engineering to control reaction pathways for selective photocatalytic nitroaromatic reduction.