Oxidation-Reduction Molecular Junction Covalent Organic Frameworks for Full Reaction Photosynthesis of H2O2.

Abstract

The full reaction photosynthesis of H2O2 that can combine water-oxidation and oxygen-reduction without sacrificial agents is highly demanded to maximize the light-utilization and overcome the complex reaction-process of traditional anthraquinone-oxidation. Here, a kind of oxidation-reduction molecular junction covalent-organic-framework (TTF-BT-COF) has been synthesized through the covalent-coupling of tetrathiafulvalene (photo-oxidation site) and benzothiazole (photo-reduction site), which presents visible-light-adsorption region, effective electron-hole separation-efficiency and suitable photo-redox sites that enables full reaction generation of H2O2. Specifically, a record-high yield (TTF-BT-COF, ~276,000 µM/h/g) for H2O2 photosynthesis without sacrificial agents has been achieved among porous crystalline photocatalysts, which is ~10 times higher than single linkers or physical-mixture. Noteworthy, it enables the facile generation of high concentration H2O2 (~18.7 wt%) in long time batch-experiment, holding much potential in practical applications. As proved by theoretical calculations, the oxidation-reduction molecular junction can facilitate the charge-transfer and largely reduce the energy-barriers of both WOR and ORR to boost the performance.