Probing the Redox Selectivity on Au@Pd and Au@Pt Bimetallic Nanoplates by Tip-Enhanced Raman Spectroscopy,ACS Photonics

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Probing the Redox Selectivity on Au@Pd and Au@Pt Bimetallic Nanoplates by Tip-Enhanced Raman Spectroscopy
ACS Photonics ( IF 6.5 ) Pub Date : 2021-06-21 , DOI: 10.1021/acsphotonics.1c00561
Zhandong Li ₁ , Dmitry Kurouski _{1,

2}

Affiliation

Bimetallic nanostructures possess unique catalytic reactivity and selectivity in plasmon-driven reactions. Such nanostructures are typically composed of plasmonic and catalytic metals. A growing body of evidence suggests that unique catalytic reactivity and selectivity of bimetallic nanostructures are determined by the intensity of the rectified electric field, the nature of the catalytic metals, and the interplay between catalytic and plasmonic metals at the nanoscale. However, the actual impact of all these factors remains unclear. In this study, we use tip-enhanced Raman spectroscopy (TERS) to determine the underlying physical cause of catalytic reactivity and selectivity of gold–platinum (Au@PtNPs) and gold–palladium (Au@PdNPs) bimetallic nanoplates. We perform nanoscale imaging of plasmon-driven oxidation of 4-mercapto-phenyl-methanol (MPM) to 4-mercaptobenzoic acid (MBA) and a reversed plasmon-driven reduction of MBA to MPM on Au@PtNPs, Au@PdNPs, and their monometallic analogues, AuNPs. Our results show that plasmon-driven reduction of MBA to MPM is evident only for Au@PdNPs, whereas Au@PtNPs exclusively possess oxidation properties enabling MPM to MBA conversion. These results show that the nature of the catalytic metal determines redox properties of bimetallic nanostructures. At the same time, none of these redox reactions are evident for AuNPs. Instead, we observe only C–C cleavage of both MPM and MBA that yields thiophenol. These findings suggest that the rectified electric field determines the reactivity of plasmon-driven reactions, whereas its intensity can be used to predict chemical transformations on these mono- and bimetallic nanostructures.

中文翻译：

通过尖端增强拉曼光谱探测 Au@Pd 和 Au@Pt 双金属纳米片的氧化还原选择性

双金属纳米结构在等离子体驱动的反应中具有独特的催化反应性和选择性。这种纳米结构通常由等离子体和催化金属组成。越来越多的证据表明，双金属纳米结构的独特催化反应性和选择性取决于整流电场的强度、催化金属的性质以及纳米级催化金属和等离子体金属之间的相互作用。然而，所有这些因素的实际影响仍不清楚。在这项研究中，我们使用尖端增强拉曼光谱（TERS）来确定金-铂（Au@PtNPs）和金-钯（Au@PdNPs）双金属纳米片的催化反应性和选择性的潜在物理原因。我们对 4-巯基苯基甲醇 (MPM) 到 4-巯基苯甲酸 (MBA) 的等离子体驱动氧化进行纳米级成像，以及在 Au@PtNP、Au@PdNP 及其上将 MBA 反向等离子体驱动还原为 MPM。单金属类似物，AuNPs。我们的结果表明，等离子体驱动的 MBA 到 MPM 的还原仅对 Au@PdNPs 很明显，而 Au@PtNPs 仅具有氧化特性，使 MPM 能够转化为 MBA。这些结果表明催化金属的性质决定了双金属纳米结构的氧化还原性能。与此同时，AuNPs 的这些氧化还原反应均不明显。相反，我们仅观察到 MPM 和 MBA 的 C-C 裂解产生苯硫酚。这些发现表明，整流电场决定了等离子体驱动反应的反应性，

更新日期：2021-07-21

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