Spatial Confinement of Photogenerated Electrons at Catalytic Sites in Covalent Organic Frameworks for Efficient Photocatalytic H<sub>2</sub>O<sub>2</sub> Production.
basic_science · Level V
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- Record sourced from PubMed, PMID 42246402.
- Also identified by DOI 10.1002/adma.73490.
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Abstract
Solar-driven synthesis of hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) offers a sustainable pathway for storing renewable energy using only water and oxygen (O<sub>2</sub>). Yet its efficiency is often constrained because photogenerated electrons recombine before reaching the O<sub>2</sub>-activation sites. To address this challenge, we developed a thiophene-bipyridine covalent organic framework (BT-Bpy-COF) that localizes photoexcited electrons directly at the catalytic centers. Ultrafast transient absorption spectroscopy and Operando X-ray photoelectron spectroscopy reveal that these confined electrons are rapidly transferred into adsorbed O<sub>2</sub>, occurring prior to electron-hole recombination. The efficient charge utilization results in markedly enhanced photocatalytic activity. As a result, BT-Bpy-COF achieves an H<sub>2</sub>O<sub>2</sub> production rate of 5.3 mmol g<sup>-1</sup> h<sup>-1</sup> under visible light with an apparent quantum yield of 6.74% at 420 nm and a solar-to-chemical conversion efficiency of 0.58%, which is 5.8 times higher than natural photosynthesis. This finding provides a versatile design strategy for advancing high-efficiency and multi-electron photocatalysis.