Symmetry-Breaking Plasmonic Mesoporous Gold Nanoparticles with Large Pores
Symmetry-Breaking Plasmonic Mesoporous Gold Nanoparticles with Large Pores
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DOI：
10.1021/acs.chemmater.2c01125
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发表时间：
2022-08-12
影响因子：
8.6
通讯作者：
Yamauchi, Yusuke
中科院分区：
文献类型：
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作者：
Nugraha, Asep Sugih;Guselnikova, Olga;Yamauchi, Yusuke
创建具有大孔的独立式金纳米颗粒（Au NP）是理想的，因为外部和内部空隙可以增强电催化活性、质量传输和消光特性。然而，Au 前驱体的高迁移率和显着的正还原电位使得制备具有足够大小的孔以与光发生强烈相互作用的 Au 纳米粒子变得具有挑战性。我们展示了一种合成具有大的、可调节孔的介孔金纳米粒子的方法。 L-半胱氨酸充当金属胶凝剂，形成致密、移动性较小的 Au(I)-硫醇盐前体，捕获聚集的嵌段共聚物胶束并促进介孔 Au NP 的还原。电子断层扫描测量表明，孔分布在颗粒的内部和外部。使用电化学方法来估计表面活性位点的化学反应性并估计孔的可接触表面积，以确保金属表面最大限度地与环境接触。然后使用断层扫描生成的 3D 模型来模拟它们的光学特性。介孔金纳米粒子支持多极等离激元共振，深入渗透到纳米粒子的内部孔隙中。一个简单的模型表明，孔隙率通过将纳米粒子细分为微小的纳米级结点来影响纳米粒子的局部光导率，这些结点使等离激元模式红移，而不改变纳米粒子的整体尺寸或形状。大孔隙促进对称性破缺，导致四极和偶极模式重叠并形成强杂化的等离激元模式。在光催化的背景下，孔隙引起的对称性破缺是有利的，因为等离子体激元的强电场沿着凹/凸特征共定位，其中原子结构中的阶梯边缘和扭结产生许多催化活性位点。使用等离子增强的金属黄光降解来证明内消旋金纳米粒子与无孔金纳米粒子相比具有优越的光催化性能。
Creating free-standing gold nanoparticles (Au NPs) with large pores is desirable because the exterior and interior voids can enhance electrocatalytic activity, mass transport, and optical extinction properties. However, the high mobility and significant positive reduction potential of Au precursors make it challenging to create Au NPs with pores of sufficient size to strongly interact with light. We demonstrate a method to synthesize mesoporous Au NPs with large, tunable pores. L-Cysteine acts as a metallogelator to form a dense, less mobile Au(I)-thiolate precursor that traps aggregated block copolymer micelles and facilitates the reduction of mesoporous Au NPs. Electron tomography measurements showed that the pores were distributed throughout the interior and exterior of the particle. Electrochemical methods were used to estimate the chemical reactivity of the surface active sites and estimate the accessible surface area of the pores to ensure that the metal surfaces were maximally accessible to the environment. The 3D models generated by tomography were then used to simulate their optical properties. Mesoporous Au NPs support multipolar plasmon resonances that penetrate deep into the interior pores of the NP. A simple model indicates that porosity affects the local optical conductivity of the NP by subdividing it into tiny nanoscale junctions that redshift the plasmon modes without changing the overall size or shape of the NPs. Large pores promote symmetry breaking, causing the quadrupolar and dipolar modes to overlap and form strongly hybridized plasmon modes. In the context of photocatalysis, porosity-induced symmetry breaking is advantageous because strong electric fields of the plasmon are colocalized along concave/convex features where step-edges and kinks in the atomic structure generate numerous catalytic active sites. Plasmon-enhanced photodegradation of metanil yellow was used to demonstrate the superior photocatalytic properties of meso Au NPs versus nonporous Au NPs.