Regulating Relative Nitrogen Locations of Diazine Functionalized Covalent Organic Frameworks for Overall H₂O₂ Photosynthesis

Abstract

Abstract Nitrogen‐heterocycle‐based covalent organic frameworks (COFs) are considered promising candidates for the overall photosynthesis of hydrogen peroxide (H 2 O 2 ). However, the effects of the relative nitrogen locations remain obscured and photocatalytic performances of COFs need to be further improved. Herein, a collection of COFs functionalized by various diazines including pyridazine, pyrimidine, and pyrazine have been judiciously designed and synthesized for photogeneration of H 2 O 2 without sacrificial agents. Compared with pyrimidine and pyrazine, pyridazine embedded in TpDz tends to stabilize endoperoxide intermediate species, leading toward the more efficient direct 2e ‐ oxygen reduction reaction (ORR) pathway. Benefiting from the effective electron‐hole separation, low charge transfer resistance, and high‐efficiency ORR pathway, an excellent production rate of 7327 μmol g −1 h −1 and a solar‐to‐chemical conversion (SCC) value of 0.62 % has been achieved by TpDz, which ranks one of the best COF‐based photocatalysts. This work might shed fresh light on the rational design of functional COFs targeting photocatalysts in H 2 O 2 production.