Atomically Thin Gold - Synthesis and Application

这个项目的第一部分解决了我们对AUNS生产的理解和形态控制。AUNS是在低浓度甲基橙(MO)存在下，在室温下通过金盐还原在水溶液中生成的。该方法需要良好的振动稳定性和温度稳定性，且生长缓慢(长达12h)。MO的一个特征性质是它的两亲性和刚性芳香族核心的结合--这种溶致‘色相’材料被认为可以自组装成2D片材和3D堆叠/柱状物，通常不需要临界浓度就可以组装。我们建议更系统地探索这种生长，我们将建造一个温度控制和振动隔离的小室，允许在定义良好的条件下进行长达24小时的研究。影响液晶组装的因素以及AUNS合成的参数的组合提供了一个大的相空间条件，以帮助更好地了解形成机制和发展对形态的控制。例如，我们将研究不同官能团(头部、尾部和芳香族核心)在控制AUNS生长方面的重要性，例如甲基红、苯磺酸和4-十二烷基苯磺酸)。此外，不同的介元聚集成不同的结构，如CI红酸266，形成中空烟囱结构，开启了模板化大直径原子薄Au纳米管的有趣可能性(理论预测它是稳定的)。除了不同的溶致介原类型外，浓度、温度、盐的存在和pH都在它们的组装中起着作用。其中已知的行为将被绘制到现有的相图上(或者将得到形成的显色体系的核磁共振/UV-Vis研究的补充)。此外，我们还将独立研究Au盐和柠檬酸还原剂浓度对成核中心数量和反应速率的影响。通过这些研究的结合，我们的目标是实现对NS产生的形态控制。用XPS、UPS、AFM、扫描开尔文探针、表面增强拉曼光谱(SERS)和相关的电子显微镜(荧光和电子显微镜)对表面修饰的AUNS进行了表征。在项目的第二部分，我们将研究这种材料的一个潜在应用--电子皮肤的发展。首先，使用四探针扫描隧道显微镜来确定单个声子源的电学性质。这使得两个或四个独立控制的STM尖端可以在扫描电子显微镜的指导下接触到物体上，并在我们的实验室中被广泛用于纳米材料的表征。[2]最后，我们将把AUNS构建到聚合物基质中，以创建基于聚合物的导电材料，并研究它们的导电性随拉伸的变化--这是开发电子皮肤等新材料的重要因素。

The first part of this project addresses our understanding and morphological control of the production of AuNS. The AuNS are produced in aqueous solution, at room temperature, via the reduction of gold salt in the presence of low concentrations of methyl orange (MO). The method requires good vibrational and temperature stability and the growth is slow (up to 12 h). A characteristic property of MO is its combination of amphiphilic nature and rigid aromatic core - such lyotropic 'chromonic phase' materials are known to self-assemble into 2D sheets and 3D stacks/columns, often with no critical concentration required for assembly.We propose to explore the growth more systematically, we will construct a temperature-controlled and vibrationally isolated chamber to allow investigations to be made for extended periods, up to 24 hr, under well-defined conditions. The combination of factors affecting LC assembly as well as the parameters for AuNS synthesis provides a large phase-space of conditions to be explored to help better understand the formation mechanism and to develop control over morphology. For example, we will look at the importance of the different functional groups (head, tail, and aromatic core) in controlling AuNS growth, eg Methyl Red Fenaminosulf and 4-Dodecylbenzenesulfonic). Further, different mesogens assemble into different structures, eg CI RED acid 266, forms hollow chimney structures opening the intriguing possibility of templating large-diameter atomically thin Au nanotubes (which are predicted by theory to be stable. In addition to the different lyotropic mesogen type, the concentration, temperature, presence of salts and pH are all known to play a role in their assembly. Where known behaviour will be mapped on to existing phase-diagrams (or will be complemented with NMR / UV-vis studies of the chromonic systems formed). We will additionally investigate, independently, the role of Au salt and citrate reductant concentration on the number of nucleation centres and reaction rates. Through the combination of these studies, we aim to achieve morphological control over the NS produced. The surface-modified AuNS will be characterised using XPS, UPS, AFM, Scanning Kelvin Probe, surface-enhanced Raman (SERS), and correlative TEM (fluorescence and TEM). In the second part of the project, we will investigate one potential application of such materials - towards the development of electronic skin. Firstly, the electrical properties of single AuNS will be determined using 4-probe STM. This allows either 2- or 4- independently controlled STM tips to be brought into contact on an object under SEM guidance and has been extensively used in our labs for the characterisation of nanomaterials.[2] Finally, we will build the AuNS into polymeric matrices to create polymer-based conductive materials and investigate their conductivity as a function of stretch - this is an important factor for the development of new materials such as electronic skin.[3]