Trifluoromethyl‐Functionalized Covalent Organic Frameworks for Efficient Photosynthesis of Hydrogen Peroxide in Pure Water

Covalent organic frameworks (COFs) have emerged as promising photocatalysts for the photosynthesis of hydrogen peroxide (H 2 O 2 ). However, the photocatalytic activity over COFs in pure water is limited due to poor carrier dynamics as well as sluggish oxygen reduction and water oxidation reactions. Herein, two β‐ketoenamine‐linked COF photocatalysts is designed via solvothermal Schiff‐base condensation: TP‐TFMB COF (with the trifluoromethyl group modification) and TP‐DADB COF (pristine COF). In pure water, TP‐TFMB COF delivers an excellent H 2 O 2 production with a yield rate of 3.83 mmol g −1 h −1 (16 folds higher than that of TP‐DADB COF) under visible‐light irradiation. As demonstrated by experimental results, the superior photocatalytic performance of TP‐TFMB COF stems from the introduction of electron‐withdrawing CF 3 groups, which simultaneously improve charge separation and promoted •O2 − generation in oxygen reduction as well as critically boost water oxidation. This work provides the insight into the effect of the electron‐withdrawing group on photocatalytic activity for H 2 O 2 generation over COFs and may enlighten the design of catalysts for H 2 O 2 photosynthesis.