Rational Design of 3D Space Connected Donor–Acceptor System in Covalent Organic Frameworks for Enhanced Photocatalytic Performance

Abstract Herein, a rational strategy is presented to reduce the energy barrier of singlet ground state to singlet excited state transitions, whilst simultaneously reducing energy losses in populating triplet excited states. The approach relies on constructing 3D space connected donor–acceptor systems in COFs. The 3D space connected D–A system in 8‐connected 3D COFs (denoted as COF‐1 and COF‐2) allows the efficient transfer of electrons, overcoming the traditional electron transport limitations of 2D COFs and significantly boosting the solar energy utilization efficiency under visible light irradiation. COF‐2, possessing an extended π‐conjugated structure relative to COF‐1, demonstrated high selectivity for the photocatalytic generation of H 2 O 2 (6.93 mmol g −1 h −1 ) in natural seawater without the need for sacrificial reagents, exceeding the performance of most previously reported COF‐based photocatalysts. The 3D space connected D–A system reported in this work offers a new approach for optimizing electron and energy transfer in COF‐based photocatalysts for H 2 O 2 production and other applications.