Chemical Mapping of Nanodefects within 2D Covalent Monolayers by Tip-Enhanced Raman Spectroscopy,ACS Nano

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Chemical Mapping of Nanodefects within 2D Covalent Monolayers by Tip-Enhanced Raman Spectroscopy
ACS Nano ( IF 15.8 ) Pub Date : 2018-04-16 00:00:00 , DOI: 10.1021/acsnano.8b02513
Feng Shao ₁ , Wenyang Dai ₂ , Yao Zhang ₃ , Wei Zhang ₄ , A. Dieter Schlüter ₂ , Renato Zenobi ₁

Affiliation

Nanoscale defects in monolayers (MLs) of two-dimensional (2D) materials, such as graphene, transition-metal dichalcogenides, and 2D polymers, can alter their physical, mechanical, optoelectronic, and chemical properties. However, detailed information about nanodefects within 2D covalent monolayers is difficult to obtain because it requires highly selective and sensitive techniques that can provide chemical information at the nanoscale. Here, we report a 2D imine-linked ML prepared from two custom-designed building blocks by dynamic imine chemistry at the air/water interface, in which an acetylenic moiety in one of the blocks was used as a spectroscopic reporter for nanodefects. Combined with density functional theory calculations that take into account surface selection rules, tip-enhanced Raman spectroscopy (TERS) imaging provides information on the chemical bonds, molecular orientation, as well as nanodefects in the resulting ML. Additionally, TERS imaging visualizes the topography and integrity of the ML at Au(111) terrace edges, suggesting possible ductility of the ML. Furthermore, edge-induced molecular tilting and a stronger signal enhancement were observed at the terrace edges, from which a spatial resolution around 8 nm could be deduced. The present work can be used to study covalent 2D materials at the nanoscale, which are expected to be of use when engineering their properties for specific device applications.

中文翻译：

尖端增强拉曼光谱在二维共价单层内纳米缺陷的化学作图

二维（2D）材料的单层（ML）中的纳米级缺陷，例如石墨烯，过渡金属二卤化物和2D聚合物，会改变其物理，机械，光电和化学特性。但是，很难获得有关2D共价单层内纳米缺陷的详细信息，因为它需要能够在纳米级提供化学信息的高度选择性和灵敏的技术。在这里，我们报告了通过空气/水界面处的动态亚胺化学反应，由两个定制设计的构建基块由两个定制设计的构建基块制备的二维亚胺基连接的ML，其中一个基块中的炔基部分用作纳米缺陷的光谱报告分子。结合考虑表面选择规则的密度泛函理论计算，尖端增强拉曼光谱（TERS）成像可提供有关所得ML中的化学键，分子取向以及纳米缺陷的信息。此外，TERS成像可以使ML在Au（111）平台边缘的形貌和完整性可视化，表明ML可能具有延展性。此外，在梯田边缘观察到边缘诱导的分子倾斜和更强的信号增强，由此可以推断出约8 nm的空间分辨率。本工作可用于研究纳米级的共价2D材料，当设计其特定设备应用的性能时，有望使用这些材料。提示ML可能具有延展性。此外，在平台边缘观察到边缘诱导的分子倾斜和更强的信号增强，由此可以推断出约8 nm的空间分辨率。本工作可用于研究纳米级的共价2D材料，当设计其特定设备应用的性能时，有望使用这些材料。提示ML可能具有延展性。此外，在平台边缘观察到边缘诱导的分子倾斜和更强的信号增强，由此可以推断出约8 nm的空间分辨率。本工作可用于研究纳米级的共价2D材料，当设计其特定设备应用的性能时，有望使用这些材料。

更新日期：2018-04-16

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