Dynamic Soft‐Confinement via Hydrogen‐Bonded Organic Frameworks Reshapes C–C Coupling Interfacial Chemistry at Bi 1 –Bi 2 Sites

ABSTRACT The core bottleneck in photocatalytic CO 2 reduction toward multi‐carbon oxygenates lies in the thermodynamic‐kinetic dual limitations of the C–C coupling step. Conventional strategies have focused on intrinsic electronic structure optimization of active sites while overlooking the critical influence of the reaction microenvironment on coupling probability. Herein, we propose a dynamic soft‐confinement catalytic strategy by in situ constructing a disordered hydrogen‐bonded organic framework (HOF) layer on Bi 3 O 4 Br surfaces, thereby establishing an HOF/Bi 3 O 4 Br integrated photocatalytic system. The introduction of HOF not only induces the formation of asymmetric Bi 1 –Bi 2 coupling sites but also establishes a dynamic hydrogen‐bonding microenvironment surrounding them. This microenvironment enhances CO 2 coverage near the coupling sites by constructing a persistent carbon source enrichment layer. Simultaneously, the interfacial polarization field promotes exciton dissociation and directs electron transport toward the Bi 1 –Bi 2 sites. Furthermore, the reconfigurable hydrogen bonds impose orientational soft confinement on *CO intermediates, guiding them into spatial configurations favorable for *OCCO bond formation. This soft‐hard synergistic interfacial design enables 0.7HOF/Bi 3 O 4 Br to achieve a CH 3 COOH production rate of 325.12 µmol g −1 h −1 with 98.81% product selectivity under sacrificial agent‐free conditions. This work demonstrates that dynamic microenvironment programming around active sites constitutes a critical pathway for overcoming the photocatalytic C–C coupling bottleneck.