Halogen Engineering in Supramolecular Halogen‐Bonded Organic Frameworks Enables Efficient Photocatalytic Hydrogen Peroxide Production

Abstract Development of stable and efficient photocatalysts for hydrogen peroxide (H 2 O 2 ) production is highly desirable. In this study, a novel class of two‐dimensional halogen‐bonded organic frameworks (XOFs), XOF(I/Br)‐TTF, was prepared using Isoquinoline‐derived electron‐rich tetrathiafulvalene and three‐center electron‐deficient N···I/Br···N + halogen bonds. XOF(I/Br)‐TTF exhibit high crystallinity, as confirmed by powder X‐ray diffraction (PXRD), high‐resolution transmission electron microscopy (HR‐TEM), selected area electron diffraction (SAED), and small‐angle X‐ray scattering (SAXS). The N⋯X⋯N + (X = I or Br) halogen bonds significantly enhance charge transfer, electron–hole separation, and intersystem crossing (ISC), leading to superior photocatalytic performance compared to the TTF monomer. Contrary to the typical heavy‐atom effect, the lighter N···Br···N + linkage in XOF(Br)‐TTF induced a narrower band gap, enhanced charge transfer, and improved intersystem crossing relative to XOF(I)‐TTF, leading to superior photocatalytic performance.XOF(Br)‐TTF achieves an exceptional H 2 O 2 production rate of 10,284 µmol g −1 h −1 in pure water without sacrificial agents and 28,200 µmol g −1 h −1 with ethanol as sacrificial agent, with an apparent quantum yield (AQY) of 18.9%. XOF(I/Br)‐TTF also demonstrated excellent photocatalytic cross‐dehydrogenative coupling (CDC) reactions, with XOF(Br)‐TTF showing superior performance. This work demonstrates the potential of halogen‐bonded organic frameworks as a versatile platform for designing efficient photocatalysts for H 2 O 2 production and organic transformations.