Keto-enol tautomerism as dynamic electron/hole traps promote charge carrier separation for hydrogen peroxide photosynthesis.
basic_science · Level V
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- Record sourced from PubMed, PMID 40790031.
- Also identified by DOI 10.1038/s41467-025-62286-9 and PMC identifier 12340163.
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Abstract
Covalent organic frameworks (COFs) are promising photocatalysts for H<sub>2</sub>O<sub>2</sub> photosynthesis, but charge carrier separation remains a critical challenge. Donor-acceptor COFs enhance charge separation, but the slow kinetics of water oxidation and oxygen reduction reactions lead to carrier accumulation, thereby decreasing efficiency. Here, we report T-C type COFs (T = trap units, C = catalytic units), demonstrating that units with keto-enol tautomerism can serve as dynamic electron/hole traps (T) to mitigate Coulomb forces. This design effectively facilitates swift charge transfer and extends carrier lifetimes, thereby enhancing reactions at the C units. Imine COFs derived from 2,4,6-trihydroxybenzaldehyde (Tp) outperform those based on 1,3,5-benzenetricarboxaldehyde due to tautomerization. The optimal Tp COF (TpBpy) achieves an H<sub>2</sub>O<sub>2</sub> generation rate of 37.9 μmol h⁻¹ (or 8350 μmol h⁻¹ g⁻¹) under simulated light, and a solar-to-chemical conversion efficiency of 0.038% in a flow reactor under natural sunlight. This work provides molecular design strategies and standard criteria for efficient H<sub>2</sub>O<sub>2</sub> photocatalysts.