Cation Exchange in Single Nanowires

单纳米线中的阳离子交换

• 批准号: 325949791
• 负责人: Professor Dr. Alf Mews, since 5/2017
• 金额: --
• 依托单位: Institut für Physikalische Chemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/325949791?language=en
• 关键词: Cation; Exchange; Single; Nanowires

Cation exchange reactions are typically very slow in macroscopic solids and are therefore often not favorable. Nanostructures, however, have very large surface to volume ratios, which enable cation exchange to progress many orders of magnitude faster than in the corresponding bulk materials. Cation exchange reactions have therefore become a very popular and efficient rout for modifying the material composition of nanostructures. However, currently relatively little is known about the kinetics of cation exchange reactions in individual nanostructures. In macroscopic solids and in ensembles of nanoparticles, cation exchange reactions appear to proceed continuously. However, in these scenarios cation exchange reactions are averaged over a multitude of domains, defects, and crystal facets. Reaction kinetics could therefore be markedly different at the single nanostructure level.The goal of our project is to control and analyze cation exchange reactions in individual nanowires in situ by means of optical and electronic measurements. As model systems we will study the well-known reactions from CdSe to Ag2Se and from CdS to Ag2S. Synthesizing and contacting single nanowires are already well established procedures in our labs. We will extend our method for in situ electrical monitoring of cation exchange on nanowire ensembles to single nanowires and to include optical measurement techniques.We plan to investigate the following questions: a) How does the electrical conductivity, fluorescence, and optical absorption change at the single nanowire level during cation exchange, and which conclusions can be drawn with respect to reaction kinetics? b) How precisely can the electronic and optical properties of individual nanowires be controlled through cation exchange? c) How homogeneous is cation exchange from CdSe to Ag2Se in single nanowires? d) Does the appearance of striped phases during the cation exchange reaction from CdS to Ag2S in nanowires have corresponding signatures in the electrical conductivity? In addition to being of basic interest in materials science, our results could find applications in semiconductor doping, battery electrodes, and in chemical sensors.

阳离子交换反应在宏观固体中通常非常缓慢，因此通常是不利的。然而，纳米结构具有非常大的表面积与体积比，这使得阳离子交换的进展速度比相应的块体材料快多个数量级。因此，阳离子交换反应已成为一种非常流行且有效的改变纳米结构材料组成的途径。然而，目前对单个纳米结构中阳离子交换反应的动力学知之甚少。在宏观固体和纳米粒子集合中，阳离子交换反应似乎连续进行。然而，在这些情况下，阳离子交换反应在多个域、缺陷和晶面上进行平均。因此，反应动力学在单个纳米结构水平上可能明显不同。我们项目的目标是通过光学和电子测量来原位控制和分析单个纳米线中的阳离子交换反应。作为模型系统，我们将研究众所周知的从 CdSe 到 Ag2Se 以及从 CdS 到 Ag2S 的反应。合成和接触单纳米线已经是我们实验室中成熟的程序。我们将把纳米线集合体上阳离子交换的原位电监测方法扩展到单纳米线，并包括光学测量技术。我们计划研究以下问题：a）在阳离子交换过程中单纳米线水平上的电导率、荧光和光吸收如何变化，以及可以得出哪些关于反应动力学的结论？ b) 通过阳离子交换可以如何精确地控制单个纳米线的电子和光学特性？ c) 单纳米线中从 CdSe 到 Ag2Se 的阳离子交换的均匀程度如何？ d) 纳米线中从 CdS 到 Ag2S 的阳离子交换反应过程中条纹相的出现是否在电导率方面具有相应的特征？除了对材料科学具有基本意义外，我们的研究结果还可以在半导体掺杂、电池电极和化学传感器中找到应用。