Regulating the 2e – ORR Pathway in Tetrazine-Based Covalent Organic Frameworks for Efficient Hydrogen Peroxide Photosynthesis

Covalent organic frameworks (COFs) as emerging oxygen reduction reaction (ORR) photocatalysts have shown great potential for artificial hydrogen peroxide (H 2 O 2 ) production but often suffered from low generation efficiency following the • O 2 – -orientated two-step 2e – ORR pathway. In this work, we constructed three isomeric COFs (COF-TpDBT, m -COF-TpDBP, and o -COF-TpDBP) based on tetrazine-cored diamines functionalized with benzene, meta -pyridine, and ortho -pyridine. o -COF-TpDBP with adjacent nitrogen atoms between ortho -pyridine and tetrazine linkage can suppress the two-step 2e – ORR pathway and facilitate a more efficient one-step 2e – ORR pathway, which exhibited remarkable H 2 O 2 photoproduction rates of 6699 μmol h –1 g –1 in pure water and 14017 μmol h –1 g –1 in the presence of benzyl alcohol. The result demonstrated that optimizing the microenvironment around active sites in COFs is an effective strategy to regulate the 2e – ORR pathway for efficient H 2 O 2 photosynthesis.