Modulating dimensional transitions in covalent organic frameworks for seawater-based photocatalytic hydrogen peroxide...

Covalent organic frameworks (COFs) with identical compositions but distinct dimensionalities are exceptionally rare, and the intrinsic relationship between their structure and photocatalytic performance remains poorly understood. Herein, we report the precise synthesis, achieved through meticulous monomer design, enabling a dimensional transition from one-dimensional (1D) chain-like structures (BS-OB-COF and BS-MB-COF) to a two-dimensional (2D) layered framework (BS-PB-COF). Compared to their 1D counterparts, the 2D COF exhibits significantly enhanced photocatalytic H₂O₂ production via the predominant two-electron oxygen reduction reaction (2e^- ORR) pathway. This improvement stems from the highly efficient carrier transport channels established through the enhanced in-plane conjugation of the donor-acceptor (D-A) network. Under oxygen atmosphere without sacrificial agents, BS-PB-COF demonstrated 3.2-fold and 1.6-fold higher seawater-based photosynthetic H₂O₂ production than small-ring 1D COFs and 1D COFs, respectively, while also exhibiting activity under near-infrared irradiation. Furthermore, BS-PB-COF demonstrated excellent stability and notable antibacterial performance. This study unveils the profound impact of dimensionality control on H₂O₂ photosynthetic performance and provides new insights for the rational design of COFs for H₂O₂ production.