| 1. |
- He, Jianqiao, et al.
(author)
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Ferrocene-integrated conjugated microporous polymer nanosheets : Active and regenerative catalysts for photomediated controlled radical polymerization
- 2020
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In: Applied materials today. - : Elsevier BV. - 2352-9407. ; 18
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Journal article (peer-reviewed)abstract
- The challenge of light-driven controlled radical polymerization through non-noble metal catalyst remains the most significant issue. Ferrocene-bearing microporous aromatic polymer nanosheets (termed FeMAP-11) that feature high chemical stability were reported here to synergistically combine the advantageous properties of the redox-active ferrocene units and the conjugated microporous polymers (CMPs), and to be able to serve as photocatalyst for activators regenerated by electron transfer atom transfer radical polymerization (AGET-ATRP). It succeeded in initiating polymerizations of 3 common vinyl monomers, i.e. methyl methacrylate (MMA), methacrylate (MA) and styrene (St), and produced polymers with controlled molecular weight and relatively low molecular weight dispersity ((1) over tilde .3). Benefiting from steric hindrance through ketone-amine chemistry, the microporous catalyst with tolerance to acidic and basic media was found stable under the AGET-ATRP conditions. It showed negligible metal leaching and good recyclability for at least 10 cycles without sacrifice of its catalytic performance. Our tests proved that FeMAP-11 exceeded the state-of-the-art ATRP photocatalysts such as UiO-66-NH2, titanium MOF-901 and the commercial P-25 Titania, demonstrating promising potential in catalysis in view of green chemistry.
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| 2. |
- Yang, Song, et al.
(author)
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Regulating the Tautomerization in Covalent Organic Frameworks for Efficient Sacrificial Agent-Free Photocatalytic H2O2 Production
- 2024
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In: Macromolecules. - 0024-9297 .- 1520-5835. ; 57:5, s. 2039-2047
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Journal article (peer-reviewed)abstract
- The efficiency of photocatalytic production of H2O2 is constrained by the low selectivity toward oxygen reduction, and the active sites are still under debate. Herein, analogous covalent organic framework photocatalysts were synthesized from triformylphloroglucinol (Tp) and predesigned diamines, in which a molecular engineering strategy was employed to manipulate the energy barrier for the targeted proton transfers. The tautomerization of enol-imine to keto-enamine introduced abundant alkene bonds (C═C), which serve as the primary adsorption sites and have a lower energy barrier for the reduction of the O2 reduction. DHAA-Tp COF displayed a remarkable photocatalytic H2O2 production rate of 219.5 μmol h–1 g–1 without any sacrificial reagent, which stands out among the structure-related materials. A switch from a concerted one-step 2e– to a two-step single e– process in O2 reduction was observed in TCNAQ-Tp COF, which is presumably ascribed to the suppressed tautomerization mediated by the strong electron-withdrawing cyano groups. The results demonstrate a novel concept for the photocatalytic production of H2O2 using an efficient, stable, and recyclable metal-free photocatalytic system.
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