This study reports the synthesis of a keto-form anthraquinone covalent organic framework (KfAQ) that can efficiently produce hydrogen peroxide (H₂O₂) from oxygen and alkaline water (pH = 13) without the need for sacrificial reagents. The KfAQ framework, mechanochemically synthesized from 2,4,6-triformylphloroglucinol (Tp) and 2,6-diaminoanthraquinone (AQ), exhibits a high H₂O₂ production rate of 4784 μmol h⁻¹ g⁻¹ at λ > 400 nm. The strong alkalinity of the solution leads to the formation of OH(H₂O)ₙ clusters, which adsorb on the keto moieties within the KfAQ framework and then dissociate into O₂ and active hydrogen, lowering the energy barrier for hydrogen extraction. The produced hydrogen reacts with anthraquinone to form anthrahydroquinone (HAQ), which is subsequently oxidized by O₂ to produce H₂O₂. This study highlights the importance of hydrogen extraction from water for H₂O₂ photosynthesis and demonstrates that H₂O₂ synthesis is achievable under alkaline conditions. The mechanism involves the adsorption of OH(H₂O)ₙ clusters on the keto moieties, followed by their dissociation into O₂ and active hydrogen, and the subsequent reaction of hydrogen with anthraquinone to form H₂O₂. The study provides insights into the design of highly active photocatalysts for efficient H₂O₂ production from water and oxygen.This study reports the synthesis of a keto-form anthraquinone covalent organic framework (KfAQ) that can efficiently produce hydrogen peroxide (H₂O₂) from oxygen and alkaline water (pH = 13) without the need for sacrificial reagents. The KfAQ framework, mechanochemically synthesized from 2,4,6-triformylphloroglucinol (Tp) and 2,6-diaminoanthraquinone (AQ), exhibits a high H₂O₂ production rate of 4784 μmol h⁻¹ g⁻¹ at λ > 400 nm. The strong alkalinity of the solution leads to the formation of OH(H₂O)ₙ clusters, which adsorb on the keto moieties within the KfAQ framework and then dissociate into O₂ and active hydrogen, lowering the energy barrier for hydrogen extraction. The produced hydrogen reacts with anthraquinone to form anthrahydroquinone (HAQ), which is subsequently oxidized by O₂ to produce H₂O₂. This study highlights the importance of hydrogen extraction from water for H₂O₂ photosynthesis and demonstrates that H₂O₂ synthesis is achievable under alkaline conditions. The mechanism involves the adsorption of OH(H₂O)ₙ clusters on the keto moieties, followed by their dissociation into O₂ and active hydrogen, and the subsequent reaction of hydrogen with anthraquinone to form H₂O₂. The study provides insights into the design of highly active photocatalysts for efficient H₂O₂ production from water and oxygen.