Synthesis and Characterization of Uniform Nanowires of Trigonal Selenium
Synthesis and Characterization of Uniform Nanowires of Trigonal Selenium
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DOI：
10.1002/1616-3028(200203)12:3
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发表时间：
2002-03
影响因子：
19
通讯作者：
B. Gates;B. Mayers;B. Cattle;Younan Xia
中科院分区：
文献类型：
--
作者：
B. Gates;B. Mayers;B. Cattle;Younan Xia
本文描述了一种软的、溶液相方法来大规模合成均匀的三角硒纳米线(t-Se)，其横向尺寸可控制在∼10到∼800 nm的范围内，长度可达数百微米。这些高度各向异性的一维(1D)纳米结构是直接从水溶液中成核和生长的，而不需要任何物理模板的帮助，例如在多孔材料中蚀刻的沟道状结构，或者由表面活性剂或嵌段共聚物组装的支架。产物的一维形态完全由构建块的线性特征决定--即t-Se晶格中包含的延伸的螺旋链原子。当直径从∼32减小到∼10 nm时，这些纳米线的带隙和链间跃迁发生了蓝移。用四探针法测量了单根纳米线的光电导，发现当样品从黑暗中取出并用∼3μWμm-2钨光曝光时，其光电导增加了150倍。由于这种合成过程不涉及外来种子，所以每根纳米线(包括两端)都应该完全由纯硒制成，在三角相中结晶。我们相信，这里描述的方案可以扩大到大规模生产t-Se纳米线，这些纳米线随后可以作为物理或化学模板来生成各种功能材料的一维纳米结构。合成策略本身也可能扩展到包含链状构建块的其他系统。这些纳米线的单晶性以及没有扭结和其他相关缺陷，应该使它们在制造纳米级电子、光学或机械纳米设备方面特别有用。
This article describes a soft, solution-phase approach to the large-scale synthesis of uniform nanowires of trigonal selenium (t-Se) with lateral dimensions controllable in the range of ∼10 to ∼800 nm, and lengths up to hundreds of micrometers. These highly anisotropic, one-dimensional (1D) nanostructures were directly nucleated and grown from aqueous solutions without the help of any physical templates, such as channel-like structures etched in porous materials, or scaffolds assembled from surfactants or block-copolymers. The 1D morphology of the product was solely determined by the linear characteristics of the building blocks—i.e., the extended, helical chains of atoms contained in the crystalline lattice of t-Se. A blue shift was observed for the bandgap and interchain transition of these nanowires when their diameters were reduced from ∼32 to ∼10 nm. The photoconductivity of individual nanowires has also been measured using the four-probe method, and an increase by ∼150 times was found when the sample was taken from the dark and exposed with ∼3 μW μm–2 tungsten light. Since no exotic seeds were involved in this synthetic process, every nanowire (including both ends) should be made entirely of pure selenium, crystallized in the trigonal phase. We believe the protocol described here can be scaled up for the high-volume production of t-Se nanowires that can subsequently serve as the physical or chemical templates to generate 1D nanostructures of various kinds of functional materials. The synthetic strategy itself, may also be extendable to other systems containing chain-like building blocks. The single crystallinity and absence of kinks and other related defects in these nanowires should make them particularly useful in fabricating nanoscale electronic, optical, or mechanical nanodevices.