Modulating Linker Conjugation in Covalent Organic Frameworks to Enable Direct Two‐Electron ORR for Boosting Photocatalytic H 2 O 2 Production and Ae
Shuangshuang Liu, Rui Zhao, Zhen Lu, Linxi HouABSTRACT
Precise regulation of photocatalytic oxygen reduction reaction (ORR) pathway, especially one‐step two‐electron (2e − ) pathway, holds great potential for achieving high efficiency in hydrogen peroxide (H 2 O 2 ) production by using covalent organic framework (COF) as photocatalysis. However, elucidating the mechanism of 2e − ORR pathway and clarifying the regulatory strategies of COF photocatalysts remain a significant challenge. Ligands play a critical role in regulating the physicochemical properties of COF and controlling the migration and transformation behavior of charge carriers. Herein, three COFs with structurally varied linkers were constructed to reveal the regulatory rules on charge carrier behavior and enhance the photocatalytic production of H 2 O 2 and oxidation performance under aerobic conditions. TPA‐TATB‐COF achieves high H 2 O 2 yield rate of up to 3.4 mmol g −1 h −1 without sacrificial agent, which is 1.7 and 4 times that of the other two COFs. Detailed theoretical studies indicate that the incorporation of triphenyl unit accelerates the separation of photoinduced electron–hole pairs and promotes Yeager‐type O 2 adsorption, facilitating one‐step 2e − ORR pathway and enhancing the aerobic oxidation of 1,1‐diphenylethylene. This work uncovers a previously overlooked structure and pathway correlation and provides a rational linker‑engineering strategy to adjust ORR pathway, accelerating both H 2 O 2 photosynthesis and selective alkene oxidation.