Atomically Thin Gold - Synthesis and Application

该项目的第一部分解决了我们对AuNS生产的理解和形态控制。在水溶液中，在室温下，通过在低浓度的甲基橙子（MO）的存在下还原金盐来产生AuNS。该方法需要良好的振动和温度稳定性，并且生长缓慢（长达12小时）。MO的一个特性是它的两亲性和刚性芳香核的组合-已知这种溶致“色相”材料自组装成2D片和3D堆叠/柱，通常不需要组装所需的临界浓度。我们建议更系统地探索生长，我们将构建一个温度控制和振动隔离的腔室，以允许长时间进行研究，在明确规定的条件下，最多24小时。影响LC组装的因素以及AuNS合成的参数的组合提供了待探索的条件的大相空间，以帮助更好地理解形成机制并开发对形态的控制。例如，我们将研究不同官能团（头部，尾部和芳香核心）在控制AuNS生长中的重要性，例如甲基红芬氨基磺酸和4-十二烷基苯磺酸。此外，不同的介晶组装成不同的结构，例如CI RED酸266，形成中空的烟囱结构，开启了模板化大直径原子级薄的Au纳米管（理论预测其是稳定的）的有趣的可能性。除了不同的溶致液晶元类型之外，已知盐的浓度、温度、存在和pH都在其组装中起作用。其中已知的行为将被映射到现有的相图（或将补充与NMR /紫外-可见光谱研究所形成的有色系统）。我们还将独立研究Au盐和柠檬酸盐还原剂浓度对成核中心数量和反应速率的作用。通过这些研究的结合，我们的目标是实现形态控制NS生产。将使用XPS、UPS、AFM、扫描开尔文探针、表面增强拉曼（Sers）和相关TEM（荧光和TEM）来表征表面改性的AuNS。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，单AuNS的电性能将使用4探针STM确定。这使得2个或4个独立控制的STM尖端在SEM引导下与物体接触，并已广泛用于我们实验室的纳米材料表征。[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作为拉伸的函数-这是开发电子皮肤等新材料的重要因素。[3]第一章

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]