Topological Insulator‐Supported Organic π ‐Dimers Enable Heterogeneous conPET Photocatalysis for Inert C–X Bond Functionalization

The photocatalytic activation of inert aryl halides remains a central challenge in organic synthesis due to their high reduction potentials and limited accessibility by conventional visible‐light photocatalysts. Herein, we report a heterogeneous photoredox system based on a topological insulator‐supported organic π ‐dimer, Sb 2 Te 3 @Rubrene 2 2+ , which enables reduction photocatalysis via a consecutive photoinduced electron transfer (conPET) mechanism. Rubrene radical cations self‐assemble into stable π ‐bonded dimers on the Sb 2 Te 3 surface, forming a closed‐shell dicationic photosensitizer that undergoes one‐electron reduction upon reductive quenching to generate [Sb 2 Te 3 @Rubrene 2 2 ] •‒ . This intermediate can be further photoexcited to achieve highly negative reduction potentials, enabling the activation of inert C─Br, C─Cl, and even C─F bonds. The resulting carbon‐centered radicals can be selectively trapped to afford dehalogenation, C─H, and C─B coupling products with broad substrate scope and high chemoselectivity. This work demonstrates a new strategy for stabilizing reactive organic intermediates through topological interfaces and establishes a heterogeneous conPET platform for reduction photocatalysis.