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

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.