Guest‐Enhanced Charge Separation in Porphyrin‐Based Double‐Cavity Metallacages for Visible‐Light‐Driven H ₂ O ₂ Production

ABSTRACT Hydrogen peroxide (H 2 O 2 ) is a versatile and green oxidant with wide industrial applications, yet its large‐scale production still relies on the energy‐intensive anthraquinone process. Photocatalytic synthesis of H 2 O 2 under visible light offers a sustainable alternative but remains limited by inefficient charge separation and mass transport in extended framework materials. Herein, we report the modular construction of two porphyrin‐based double‐cavity metallacages via orthogonal Pt(II)/carboxylate/pyridine and Zn‐porphyrin/pyridine coordination. The resulting metallacages feature an intrinsic donor‐acceptor architecture that promotes photoinduced electron transfer and charge separation. Encapsulation of electron‐rich aromatic guests (triphenylene or benzotrithiophene) further stabilizes the charge‐separated state and prolongs carrier lifetimes, thereby enhancing the photocatalytic H 2 O 2 generation with a rate of 4037 µmol·g −1 ·h −1 in the presence of benzyl alcohol, among the highest reported values for visible‐light supramolecular photocatalysts. This work establishes discrete metallacages and their host–guest complexes as an emerging platform for supramolecular photocatalysis and rational H 2 O 2 photosynthesis, which will pave the way for the future development of metallacages in photocatalytic applications.