Modulation of Anthraquinone Moieties in Covalent Organic Framework for Efficient Photocatalytic H2o2 Production from Water and Dioxygen

Photocatalytic H2O2 production is a promising strategy to realize its decentralized application but limited by the low production efficiency in the absence of organic sacrifice. Herein, anthraquinone functionalized covalent organic frameworks (TpAQ-COFs) were fabricated by β-ketoenamines links of 2,6-diaminoanthraquinone (AQ) and 2, 4, 6-triformylphloroglucinol (Tp), and the structures and compositions were tuned by controlling the condensation time. The extending of condensation time favors to produce more ordered lamellar stacking structure and increase enol-imine contents. The critical role of anthraquinone moieties as the active sites for oxygen reduction was proved, that is, facilitating charge separation and enhancing the activity and selectivity of H2O2 production. Upon visible light irradiation, the TpAQ-COF after 12 h condensation has the highest content of anthraquinone moieties and the best performance for H2O2 production (420 μmol h-1g-1) from pure water. These findings bring insights to incorporate anthraquinone chemistry into photocatalysts at molecular levels for efficient H2O2 production.