Materials World Network: The Designer Nanoparticle

如果反应物（即，金属离子和还原剂）通过它们在两个（不混溶的）液相中的位置而彼此物理分离。 然后在这两个液相之间的界面处发生纳米颗粒的成核和生长。 伊利诺伊大学芝加哥分校和英国曼彻斯特大学之间的合作使用最先进的X射线光谱学，表面散射和电化学技术来研究分子水平上的颗粒生长，因为它发生在液/液界面上。 在界面处的这种定位允许使用X射线吸收，其不容易检测均匀分散在整个溶液体积中的颗粒，但是可以应用于界面情况，因为颗粒高度集中在界面处。X射线吸收光谱探测非晶体系统中的局部几何和电子结构，包括确定原子的化学物质和化学状态。除了这种光谱探针，研究人员还使用结构探针，X射线表面散射，来研究平面内和平面外的结构，包括颗粒的形状，大小和组织，以及界面附近反应物物种的耗尽。 这些X射线技术与液/液界面反应的电化学控制相结合，既可以监测颗粒生长的进展，也可以研究施加的电势对控制颗粒产生的影响。该项目为学生提供了一个由英国和美国的科学专业知识塑造的研究环境。 学生参加联合小组会议（通过视频电话会议），并前往两国的实验室学习X射线光谱学，表面散射和广泛的电分析化学技术，用于研究界面处的纳米粒子。预计对金属纳米颗粒成核和生长的分子水平的理解将允许生产具有设计性质的纳米颗粒。 这将影响纳米粒子在许多领域的应用，包括催化，光电和涂层应用的新材料的设计。

The study of the growth process of metal nanoparticles is greatly simplified if reactants (i.e., metal ion and reducing agent) are physically separated from one another, by their location in two (immiscible) liquid phases. Nucleation and growth of the nanoparticles then takes place at the interface between these two liquid phases. This collaboration between the University of Illinois at Chicago and the University of Manchester in the United Kingdom uses state-of-the-art X-ray spectroscopy, surface scattering and electrochemistry techniques to investigate particle growth on the molecular level as it occurs at the liquid/liquid interface. Such localization at the interface allows for the use of X-ray absorption, which would not readily detect particles dispersed homogeneously throughout a solution volume, but can be applied in the interfacial case because the particles are highly concentrated at the interface. X-ray absorption spectroscopy probes the local geometric and electronic structure in non-crystalline systems, including determination of the chemical species and the chemical state of the atoms. In addition to this spectroscopic probe, the investigators use a structural probe, X-ray surface scattering, to study the in-plane and out-of-plane structure, including the shape, size, and organization of the particles, as well as the depletion of reactant species near the interface. These X-ray techniques are combined with electrochemical control of the interfacial reaction at the liquid/liquid interface, both to monitor the progress in particle growth as well as to investigate the influence of the applied potential in controlling particle production.This project provides students with a research environment shaped by scientific expertise from the UK and USA. Students participate in joint group meetings (by video teleconferencing) and travel to laboratories in both countries to learn X-ray spectroscopy, surface scattering, and a broad range of electro-analytical chemistry techniques for the study of nanoparticles at interfaces. It is anticipated that a molecular-level understanding of metal nanoparticle nucleation and growth will allow for the production of nanoparticles with designed properties. This should influence the development of applications of nanoparticles in a number of areas, including the design of new materials for catalytic, opto-electronic, and coating applications.