Interface-Engineered Bismuthene/PCN-222 Heterojunctions for the Visible-Light Photoredox C–H Arylation of (Hetero)arenes

The photocatalytic performance of semiconductor metal–organic frameworks (MOFs) is often limited by rapid charge-carrier recombination, insufficient visible-light absorption, and weak interfacial interactions in heterojunctions, highlighting the need for synthetic strategies that enable strong interfacial coupling for efficient charge transfer. Herein, we rationally engineered MOF/2D semiconductor heterojunctions through two different assembly strategies: physical mixing (P) and in situ interfacial growth (I). The heterojunctions were formulated by using bismuthene (Biene) and PCN-222 MOF via either mechanical blending (Biene/PCN-222(P)) or chemical integration (Biene/PCN-222(I)). In the visible-light-driven C–H arylation of (hetero)arenes, Biene/PCN-222(I) exhibited markedly superior photocatalytic activity compared with the individual components and the physically assembled counterpart while also demonstrating a broad substrate scope. Notably, excellent catalytic performance was maintained even for benzene, which is one of the most challenging substrates. The superior performance of the in situ-assembled Biene/PCN-222(I) heterojunction is attributed to the formation of a strongly coupled interface and complex type-II band alignment, which synergistically suppress charge-carrier recombination and promote directional interfacial charge migration, thereby improving charge-separation and charge-transfer efficiencies under visible-light irradiation. Mechanistic studies further confirmed the generation of aryl-radical intermediates during the photocatalytic process, validating the single electron transfer pathway.