Ultrafast Charge Dynamics in Nitrogen‐Rich Covalent Organic Frameworks for Hydrogen Peroxide Photosynthesis

Abstract Four new tetrazine‐based COFs, DT‐COF‐ n ( n = 0–3, indicating the number of ─OH groups), incorporating diamino‐bis‐tetrazine and hydroxy‐functionalized benzo‐tri‐carbaldehyde monomers are used to explore the link between bonding reversibility in supramolecular chemistry and photocatalytic H 2 O 2 production. DT‐COFs exhibit an exceptionally high nitrogen content, with 72 nitrogen atoms per pore structure, accounting for 50.3% of the framework composition‐far exceeding previously reported COFs with less than 32% nitrogen. This high nitrogen density, coupled with the strong electron‐accepting nature of tetrazine units and an azo linker, promotes charge separation and stabilization, critical for efficient photocatalysis. DT‐COF‐1, which includes a single hydroxyl group, shows a highly ordered structure and extended conjugation. This led to a H 2 O 2 yield of 4300 µmol g −1 h −1 and an apparent quantum yield of 14.1% at 420 nm under visible light in water. With respect to peroxide yield and quantum yield, DT‐COF‐1 outperforms most other COFs used to produce peroxide. DT‐COF‐1 also achieves ultrafast intramolecular electron transfer (<500 fs) and a prolonged excited state lifetime (≈90 ps). In situ electron paramagnetic resonance spectroscopy and DFT calculations suggest a Yeager‐type absorption of O 2 •− intermediate, favoring H 2 O 2 production.