Constructing Synergistic Triazine and Acetylene Cores in Fully Conjugated Covalent Organic Frameworks for Cascade Photocatalytic H2O2 Production

Covalent organic frameworks (COFs) are an ideal template for photocatalytic H2O2 synthesis because of the tunable chemical structures and semiconductor properties. However, the photoactivity for COFs is still under-improved due to the inefficient intrinsic charge generation, fast recombination of photogenerated charges, and limited electron transport along the frameworks. Herein, spatially separated and synergistic triazine and acetylene units are first integrated into COFs (EBA-COF and BTEA-COF) for photocatalytic H2O2 production. The spatial separation of triazine and acetylene cores leads to efficient charge separation and suppressed charge recombination, and C═C linkage facilitates electrons transport over the skeletons. Both experimental and computational results suggested that triazine and acetylene units synergistically promote H2O2 synthesis in a two-electron pathway. The EBA-COF showed an attractive activity with a H2O2 production rate of 1830 μmol h-1 gcat-1, superior to that of most other COF-based catalysts. This study provides a method for designing photocatalysts with synergistic photocatalytic active sites based on vinylene-linked COFs