Accelerated oxygen activation over uranyl decorated covalent organic framework for universally promoted H2O2 photosynthesis
Photocatalytic synthesis has been considered a promising technology for solar-to-chemicals conversion. Here, a series of novel photocatalysts was synthesized by decorating uranyl sites on imine-based covalent organic frameworks (i-COF) and proved functioning for the uniformly boosted H2O2 production by 1.6–10.1 folds compared with the bare i-COFs in a wide pH range from 2 to 11. Typically, an optimal H2O2 production rate of 1435.9 μmol g−1 h−1, i.e., 28.72 mmol g(U)−1 h−1, was realized over uranyl decorated TTa-COFs under visible light. Systematic investigations reveal that the universally and remarkably promoted performance is attributed to the outstanding electron-transfer ability, accelerated activation of molecular oxygen and favored formation of ·O2− and *OOH as the key intermediate by virtue of the decorated uranyl ions; thus the two-step single-electron oxygen reduction reaction (ORR) for H2O2 photo-generation is significantly facilitated. This work paves a new way for the uranyl-decorated COFs as a novel photocatalyst and provides in-depth insight to the reaction mechanism for photocatalytic H2O2 production.