Nanosphere Synthesis and the Impact of Curvature on Molecule Adsorption

化学系的大分子、超分子和纳米化学项目将资助弗吉尼亚大学的Petra Reinke教授开发新型的、由碳（碳化物）与金属化学结合而成的超小型催化剂颗粒。这些直径小于几十亿分之一米的颗粒具有广泛的潜在应用，从催化到分子电子学，从碳化物基颗粒可以替代昂贵的贵金属。该项目解决了两个挑战，这也是使用碳化物基纳米颗粒的关键瓶颈：首先，合成具有狭窄尺寸分布的稳定碳化物基纳米颗粒，可以适应其最大限度地提高性能；其次，了解几何和电子结构对化学反应性的影响。外展活动和基于网络的、学生设计的纳米技术资源的开发与研究计划相结合。纳米粒子曲率作为分子吸附几何的控制参数，在驱动自下而上组装中具有强大的功能。目前的建议目标的大小制度，分子的大小变得相当的金属或半导体纳米颗粒的直径，它被吸附。本文的工作主要针对两个方面，一是合成稳定的超小纳米颗粒（纳米球）作为模型体系，二是研究分子吸附。纳米球是由作为碳支架的富勒烯和金属衬底之间的固态反应形成的。研究纳米球的形成机制，以控制其组成、键合和表面结构。本文将主要利用扫描隧道显微镜和光谱学技术研究纳米球的合成机理以及冠烯在纳米球上的吸附。基于同步加速器的光电子能谱将用于阐明分子中的键合和吸附引起的变化。实验工作将整合(i)统计图像分析，（ii）曲面尖端卷积模拟，以及（iii）用密度泛函方法模拟金属-分子相互作用和纳米球形成。

With this award, the Macromolecular, Supramolecular and Nanochemistry program in the Division of Chemistry is funding Professor Petra Reinke at the University of Virginia to develop novel, ultrasmall catalyst particles that consist of carbon (carbides) chemically bound to a metal. These particles, with diameters of less then a few billionths of a meter, havea wide range of potential applications, from catalysis, where carbide-based particles can substitute for expensive noble metals, to molecular electronics. The project addresses two challenges, which are critical bottlenecks for the use of carbide-based nanoparticles: First, the synthesis of stable carbide-based nanoparticles with a narrow size distribution, which can be adapted to maximize performance, and second, understanding the impact of geometric and electronic structure on chemical reactivity. Outreach activities, and the development of a web-based, student-designed nanotechnology resources are integrated with the research program. Nanoparticle curvature, as a control parameter for molecule adsorption geometry, has the potential to function as a powerful tool in driving bottom-up assembly. The present proposal targets the size regime where molecule size becomes comparable to the diameter of a metallic or semiconducting nanoparticle on which it is adsorbed. The proposed work targets two areas, first, the synthesis of stable ultra-small nanoparticles (nanospheres) as model systems, and, second, the study of molecule adsorption. The nanospheres are formed by a solid-state reaction between fullerenes, which serve as the carbon scaffold, and a metal substrate. The mechanism of nanosphere formation will be studied to control composition, bonding and surface structure. The mechanisms of nanosphere synthesis, and the adsorption of coronene on these nanospheres will be studied mainly with scanning tunneling microscopy and spectroscopy. Synchrotron-based photoelectron spectroscopy will be applied to elucidate bonding, and adsorption-induced changes in the molecule. The experimental work will be integrated with (i) statistical image analysis, (ii) simulation of tip convolution for curved surfaces, and (iii) simulation of metal-molecule interaction and nanosphere formation with DFT (density functional methods).