Visible-Light-Driven Hydrogen Peroxide Production from Water and Dioxygen by Perylenetetracarboxylic Diimides Modified Titanium-Based Metal–Organic Frameworks

Metal‒organic frameworks (MOFs) are promising materials for photocatalytic hydrogen peroxide (H2O2) production from water (H2O) and dioxygen (O2). However, H2O2 production from H2O and O2 using MOFs has remained challenging due to the fast recombination of photogenerated charges in MOFs matrix. Herein, a heterojunction structure was constructed by modification of an organic semiconductor, perylenetetracarboxylic diimide (PDI) upon a titanium-based MOF (MIL-125-NH2), forming MIL-125-PDI to promote the separation of photogenerated charges between PDI and MOFs. As a result, the as-formed MIL-125-PDI displayed a H2O2 production rate of 4800 μM • g–1 • h–1, which was 4.3 times that of the pristine MIL-125-NH2 under visible-light irradiation (λ > 420 nm). Furthermore, MIL-125-PDI exhibited a better durability, compared with MIL-125-NH2 with noble-metallic Pt nanoparticles as co-catalysts. The results of trapping experiments of active species for H2O2 production indicated that a new one-step two-electron process of O2 reduction to H2O2 occurred in MIL-125-PDI, while the original one was two-step one-electron process in MIL-125-NH2. This work used MOFs as the main active component in photocatalysts, which opens up the new application of MOFs in photocatalysis and provides an effective strategy to design MOFs-based photocatalysts for the artificial photosynthesis of clean liquid fuels.