Li Zhandong, Kurouski Dmitry
Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, United States.
The Institute for Quantum Science and Engineering, Texas A&M University, College Station, Texas 77843, United States.
Acc Chem Res. 2021 May 18;54(10):2477-2487. doi: 10.1021/acs.accounts.1c00093. Epub 2021 Apr 28.
ConspectusHot carriers are highly energetic species that can perform a large spectrum of chemical reactions. They are generated on the surfaces of nanostructures via direct interband, phonon-assisted intraband, and geometry-assisted decay of localized surface plasmon resonances (LSPRs), which are coherent oscillations of conductive electrons. LSPRs can be induced on the surface of noble metal (Ag or Au) nanostructures by illuminating the surfaces with electromagnetic irradiation. These noble metals can be coupled with catalytic metals, such as Pt, Pd, and Ru, to develop bimetallic nanostructures with unique catalytic activities. The plasmon-driven catalysis on bimetallic nanostructures is light-driven, which essentially enables green chemistry in organic synthesis. During the past decade, surface-enhanced Raman spectroscopy (SERS) has been actively utilized to study the mechanisms of plasmon-driven reactions on mono- and bimetallic nanostructures. SERS has provided a wealth of knowledge about the mechanisms of numerous plasmon-driven redox, coupling, and scissoring reactions. However, the nanoscale catalytic properties of both mono- and bimetallic nanostructures as well as the underlying physical cause of their catalytic reactivity and selectivity remained unclear for decades.In this Account, we focus on the most recent findings reported by our and other research groups that shed light on the nanoscale properties of mono- and bimetallic nanostructures. This information was revealed by tip-enhanced Raman spectroscopy (TERS), a modern analytical technique that has single-molecule sensitivity and subnanometer spatial resolution. TERS findings have shown that plasmonic reactivity and the selectivity of bimetallic nanostructures are governed by the nature of the catalytic metal and the strength of the rectified electric field on their surfaces. TERS has also revealed that the catalytic properties of bimetallic nanostructures directly depend on the interplay between the catalytic and plasmonic metals. We anticipate that these findings will be used to tailor synthetic approaches that are used to fabricate novel nanostructures with desired catalytic properties. The experimental and theoretical results discussed in this Account will facilitate a better understanding of TERS and explain artifacts that could be encountered upon TERS imaging of a large variety of samples. Consequently, plasmon-driven chemistry should be considered as an essential part of near-field microscopy.
综述热载流子是具有高能量的物种，能够进行多种化学反应。它们通过直接带间跃迁、声子辅助带内跃迁以及局域表面等离子体共振（LSPR）的几何辅助衰减在纳米结构表面产生，LSPR是导电电子的相干振荡。通过用电磁辐射照射贵金属（Ag或Au）纳米结构表面，可以诱导产生LSPR。这些贵金属可以与催化金属（如Pt、Pd和Ru）耦合，以开发具有独特催化活性的双金属纳米结构。双金属纳米结构上的等离子体驱动催化是光驱动的，这在有机合成中本质上实现了绿色化学。在过去十年中，表面增强拉曼光谱（SERS）已被积极用于研究单金属和双金属纳米结构上等离子体驱动反应的机制。SERS提供了大量关于众多等离子体驱动的氧化还原、偶联和剪接反应机制的知识。然而，几十年来，单金属和双金属纳米结构的纳米级催化性能以及它们催化反应性和选择性的潜在物理原因仍不清楚。在本综述中，我们关注我们和其他研究小组最近报道的揭示单金属和双金属纳米结构纳米级性质的发现。这些信息是通过针尖增强拉曼光谱（TERS）揭示的，TERS是一种具有单分子灵敏度和亚纳米空间分辨率的现代分析技术。TERS研究结果表明，双金属纳米结构的等离子体反应性和选择性受催化金属的性质及其表面整流电场强度的控制。TERS还揭示了双金属纳米结构的催化性能直接取决于催化金属和等离子体金属之间的相互作用。我们预计这些发现将用于定制合成方法，以制造具有所需催化性能的新型纳米结构。本综述中讨论的实验和理论结果将有助于更好地理解TERS，并解释在对各种样品进行TERS成像时可能遇到的假象。因此，等离子体驱动化学应被视为近场显微镜的重要组成部分。
