为什么表面疏水性促进CO2电还原：疏水性聚合物N-杂环卡宾的案例研究,Chemical Science

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为什么表面疏水性促进CO2电还原：疏水性聚合物N-杂环卡宾的案例研究
Chemical Science ( IF 7.6 ) Pub Date : 2023-08-08 , DOI: 10.1039/d3sc02658b
Qiang Luo ₁ , Hanyi Duan ₂ , Michael C McLaughlin ₁ , Kecheng Wei ₃ , Joseph Tapia ₄ , Joseph A Adewuyi ₁ , Seth Shuster ₁ , Maham Liaqat ₁ , Steven L Suib ₁ , Gaël Ung ₁ , Peng Bai ₄ , Shouheng Sun ₃ , Jie He _{1,

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Affiliation

我们报道了使用聚合物N-杂环卡宾（NHC）来控制金属纳米催化剂周围的微环境，从而增强其在CO ₂电还原中的催化性能。设计了三种具有不同疏水性的聚合物NHC配体：亲水性聚环氧乙烷（PEO-NHC）、疏水性聚苯乙烯（PS-NHC）和两亲性嵌段共聚物（BCP）（PEO-b-PS-NHC ）。所有三种聚合物NHC在CO ₂电还原过程中通过抑制质子还原而表现出增强的金纳米颗粒(AuNP)的反应性。值得注意的是，与亲水性 PEO-NHC 相比， PS-NHC 和 PEO- b -PS-NHC中疏水性 PS 片段的掺入导致 CO 形成的部分电流密度增加了一倍。虽然聚合物配体不会阻碍离子扩散，但它们的疏水性改变了水的局部氢键结构。这通过衰减全反射表面增强红外吸收光谱和分子动力学模拟在实验和理论上得到证实，证明了疏水性聚合物存在下CO _{2扩散的改善和随后的减少。}此外，与硫醇末端聚合物不同，NHC 在还原条件下表现出合理的稳定性，保持了 AuNP 的结构完整性。NHC 结合基序与疏水性聚合物的结合为控制金属纳米催化剂的微环境提供了宝贵的见解，为人工金属酶的设计提供了一种仿生策略。

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Why surface hydrophobicity promotes CO2 electroreduction: a case study of hydrophobic polymer N-heterocyclic carbenes

We report the use of polymer N-heterocyclic carbenes (NHCs) to control the microenvironment surrounding metal nanocatalysts, thereby enhancing their catalytic performance in CO₂ electroreduction. Three polymer NHC ligands were designed with different hydrophobicity: hydrophilic poly(ethylene oxide) (PEO–NHC), hydrophobic polystyrene (PS–NHC), and amphiphilic block copolymer (BCP) (PEO-b-PS–NHC). All three polymer NHCs exhibited enhanced reactivity of gold nanoparticles (AuNPs) during CO₂ electroreduction by suppressing proton reduction. Notably, the incorporation of hydrophobic PS segments in both PS–NHC and PEO-b-PS–NHC led to a twofold increase in the partial current density for CO formation, as compared to the hydrophilic PEO–NHC. While polymer ligands did not hinder ion diffusion, their hydrophobicity altered the localized hydrogen bonding structures of water. This was confirmed experimentally and theoretically through attenuated total reflectance surface-enhanced infrared absorption spectroscopy and molecular dynamics simulation, demonstrating improved CO₂ diffusion and subsequent reduction in the presence of hydrophobic polymers. Furthermore, NHCs exhibited reasonable stability under reductive conditions, preserving the structural integrity of AuNPs, unlike thiol-ended polymers. The combination of NHC binding motifs with hydrophobic polymers provides valuable insights into controlling the microenvironment of metal nanocatalysts, offering a bioinspired strategy for the design of artificial metalloenzymes.

更新日期：2023-08-08

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