Tailoring asymmetric electron distribution in covalent organic frameworks to regulate electron- and energy-transfer processes for efficient hydrogen peroxide photosynthesis

A series of COFs with different degrees of in-plane electron asymmetry distribution were successfully constructed. • NS-COF exhibits the strongest in-plane and intramolecular asymmetric polarization and donor-acceptor interactions. • Strongest local asymmetric electron distribution builds side-on Yeager-type O 2 bonding sites with enhanced adsorption. • NS-COF achieves outstanding H 2 O 2 photosynthesis of 7882 μmol·g −1 ·h −1 in pure water and air without sacrificial agents. Conventional photocatalysts generally rely on optimizing charge-transfer processes or specific oxygen activation pathways, while the molecular-level regulation of coupled excited-state and oxygen activation processes remains challenging. Simultaneously regulating charge-transfer and energy-transfer-related oxygen activation processes within a photocatalyst remains a significant challenge. Herein, we present a targeted strategy to finely tailor the asymmetric electron distribution of covalent organic framework (COF) to regulate charge-transfer and energy-transfer-related oxygen activation processes for superior H 2 O 2 photosynthesis. The results reveal that NS-COF regulates excited-state behavior and electron transport dynamics through linkage-controlled electronic modulation. The enhanced in-plane polarization promotes spin-state conversion and intersystem crossing (ISC), facilitating efficient triplet-state generation and energy-transfer-related oxygen activation. Furthermore, the lone-pair electrons of heteroatoms can partially delocalize onto the aromatic backbone, modulating the HOMO and LUMO energy levels and facilitating charge-transfer processes. Additionally, the enhanced local asymmetric electron distribution in NS-COF creates a polarized microenvironment that favors O 2 adsorption in a Yeager-type configuration with strengthened interaction. Upon electron injection, this adsorbed O 2 generates surface-bound •O 2 - species, which undergo subsequent protonation to form *OOH intermediates, thereby promoting the stepwise two-electron oxygen reduction pathway (O 2 → •O 2 - → *OOH → H 2 O 2 ), while also enabling an energy-transfer-related oxygen activation process involving 1 O 2 generation and subsequent H 2 O 2 formation (O 2 → 1 O 2 → H 2 O 2 ). These complementary processes collectively contribute to the enhanced H 2 O 2 production activity, resulting in a superior H 2 O 2 production rate of 10885 μmol g cat. −1 h −1 in pure water and oxygen. The feasibility of regulating complementary charge-transfer and energy-transfer-related excited-state processes provides new perspectives for photocatalysis, optoelectronic devices, and energy storage. Download: Download high-res image (290KB) Download: Download full-size image