Keto-anthraquinone covalent organic framework for H 2 O 2 photosynthesis with oxygen and alkaline water.

Hydrogen peroxide photosynthesis suffers from insufficient catalytic activity due to the high energy barrier of hydrogen extraction from H 2 O. Herein, we report that mechanochemically synthesized keto-form anthraquinone covalent organic framework which is able to directly synthesize H 2 O 2 (4784 μmol h -1 g -1 at λ > 400 nm) from oxygen and alkaline water (pH = 13) in the absence of any sacrificial reagents. The strong alkalinity resulted in the formation of OH - (H 2 O) n clusters in water, which were adsorbed on keto moieties within the framework and then dissociated into O 2 and active hydrogen, because the energy barrier of hydrogen extraction was largely lowered. The produced hydrogen reacted with anthraquinone to generate anthrahydroquinone, which was subsequently oxidized by O 2 to produce H 2 O 2 . This study ultimately sheds light on the importance of hydrogen extraction from H 2 O for H 2 O 2 photosynthesis and demonstrates that H 2 O 2 synthesis is achievable under alkaline conditions.