Confinement‐Deconfinement Engineering Induces Ultrastrong Dipole Moments in Metastable Assemblies: Driving Leap in Photocatalytic Hydrogen Evolution Efficiency

Abstract The high exciton binding energy ( E b ) in symmetric organic photocatalysts has long hindered solar‐to‐hydrogen efficiency. Here, a confinement‐deconfinement engineering strategy is presented that transforms molecular symmetry from an intrinsic limitation into a tunable design parameter. By confining symmetric molecules within layered double hydroxide interlayers, a highly oriented stacking configuration is enforced, compelling molecules to deviate from their thermodynamically stable modes. Subsequent deconfinement preserves this metastable structure. This confinement‐deconfinement synergy induces giant dipole moments (22.50 Debye) and internal electric fields, collectively reducing E b to 44.42 meV (comparable to inorganic semiconductors). Interfacial water molecules activated by deconfinement act as structural co‐architects, further dynamically stabilizing the metastable supramolecular assemblies (SA) via hydrogen‐bonding networks. The optimized SA achieves a hydrogen evolution rate of 100.48 mmol · g −1 · h −1 , representing the current state‐of‐the‐art. These results establish confinement‐deconfinement engineering as a universal paradigm for enhancing photocatalytic performance, as it enables controlled symmetry‐to‐function conversion across diverse symmetric molecular systems.