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

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 pi-conjugated structure relative to COF-1, demonstrated high selectivity for the photocatalytic generation of H2O2 (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 H2O2 production and other applications. A 3D space connected donor-accepter system is constructed to simultaneously reduce the energy barrier of electron transfer from the ground state to singlet excited states and also minimize energy losses in reaching triplet excited states in covalent organic frameworks (COFs), thereby boosting photocatalytic H2O2 production performance in seawater. This allows a deeper understanding of the photocatalytic mechanism of COFs. image