论文总字数：27687字

摘 要

二维纳米材料具有优良的光学、电学特性，近年来受到了广泛的关注，在电子、能源、材料、医学等领域都有诸多的应用。二维纳米材料中一种非天然的折叠结构作为一个新兴的研究热点，不仅具有二维纳米薄片本身的优点，同时又有新颖的光致发光性能和宽间接带隙，对于开发新一代薄膜器件有着重要的研究意义。

本文对二维纳米材料的制备方法、表征手段以及折叠结构的最新研究进展和应用前景做了简要介绍。使用机械剥离法制备了少层二硫化钼（MoS₂）纳米薄片，并使用光学显微镜、超低波拉曼光谱仪和原子力显微镜对其中含有折叠结构的样品进行了表面形貌和层间相互作用的表征。

研究结果表明，MoS₂折叠结构中层间耦合作用的强弱决定了超低波拉曼图谱中峰的位置及强弱，对拉曼峰的进一步分析表明折叠结构中存在较弱、中等和较强等三种不同强度的耦合作用。下一步可结合理论计算与高分辨原子力显微镜，探究折叠角度与折叠结构中层间耦合作用强度之间的关系，制备新一代的光电器件。

关键词：二维纳米材料 折叠结构 机械剥离法 二硫化钼 超低波拉曼光谱 原子力显微镜

Preparation and Characterization of Folded Few-Layer Molybdenum Disulfide Nanosheets

Abstract

In recent years, two-dimensional (2D) nano-materials have been extensively concerned in the fields of electronics, energy, materials, medicine and so on due to their excellent optical and electrical properties. As one of the novel hotspots, folded few-layer MoS₂ nanosheet has excellent photoluminescence and enlarged indirect band gap while maintains its intrinsic properties. It may provide desirable electronic and optical properties to engineer transition metal dichalcogenide for preparing new generation of thin film devices.

In the first part of this work, preparation and characterization of two-dimensional nano-materials, as well as the state-of-art of the folded 2D nano-materials are briefly introduced. After MoS₂ nanosheets were prepared by mechanical exfoliation, the folded few-layer MoS₂ nanosheets were identified by optical microscopy. The surface morphology, interlayer interaction and other aspects of the folded MoS₂ nanosheets were characterized by ultra-low frequency Raman spectroscopy and atomic force microscopy.

The interlayer coupling strength in folded MoS₂ nanosheets determines the strength and position of the peaks in the ultra-low frequency Raman spectra. Analysis of Raman peaks indicates there are three kinds of coupling with different intensities, i.e., weak, middle and strong couplings. The next step is to explore the relationship between the folding angle and coupling strength in the folded structure by theoretical calculation in combination with high-resolution atomic force microscopy, which shows potential for preparing new generation of optoelectronic devices.

Key Words: Two-dimensional nano-material; folded structure; mechanical exfoliation; molybdenum disulfide; ultra-low frequency Raman spectroscopy; atomic force microscopy; optical microscopy

目 录

摘 要 I

Abstract II

第一章 引言 1

1.1 二维纳米材料简介 1

1.2 二维纳米材料的研究进展 2

1.3 二维纳米材料的制备方法 3

1.3.1 机械剥离法 3

1.3.2 液相剥离法 4

1.3.3 锂离子插层法 5

1.3.4 化学气相沉积法（CVD） 5

1.3.5 水热法 6

1.4 二维纳米材料的表征手段 6

1.4.1 光学显微镜 6

1.4.2 拉曼光谱仪 7

1.4.3 原子力显微镜 8

1.5 二维纳米材料的折叠结构简介 9

1.5.1 折叠结构的定义 9

1.5.2 折叠结构的获得方法 9

1.5.3 折叠结构的特点 10

1.5 小结 10

1.6 本论文研究内容及创新点 11

1.6.1 研究内容 11

1.6.2 创新点 11

第二章 MoS₂纳米薄片的制备和表征 12

2.1 实验试剂、仪器、及表征设备 12

2.1.1 实验试剂 12

2.1.2 实验仪器 12

2.1.3 表征仪器 13

2.2 MoS₂折叠结构的制备 13

2.2.1 切割衬底 13

2.2.2 清洗衬底 13

2.2.3 机械剥离法制备MoS₂样品 13

2.3 MoS₂折叠结构的表征 14

2.3.1 光学显微镜表征 14

2.3.2 超低波拉曼光谱仪表征 14

2.3.3 原子力显微镜表征 14

2.4 实验结果与讨论 15

2.4.1 光学图像分析 15

2.4.2 原子力显微镜图像分析 16

2.4.3 超低波拉曼光谱分析 17

2.5 实验结论 20

2.6 总结与展望 20

参考文献 21

附 录 26

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