Size-dependent electrochemistry of redox active nanoparticles

亚利桑那州立大学的Daniel A.Buttry教授在化学系的支持下，研究了尺寸和表面应力对金属和金属氧化物纳米颗粒的电化学性质和相变的影响，特别是Ag氧化为AgCl，Pd还原为PdHx，以及层状LixMnO2转化为尖晶石LixMn2O4。将开发简便的合成方法和粒度分级方法，以控制尺寸在1.5-10 nm范围内的Ag、Pd和MnO2纳米颗粒。这些颗粒将被三磷酸腺苷(ATP)覆盖，以促进它们在高浓度的水支持电解质中溶解，从而能够研究它们在薄层薄膜中的电化学行为和作为单独溶解的纳米颗粒。这些颗粒将接受一系列分析表征技术，以确定它们的大小和组成。表面应力将由晶格收缩测量确定。纳米材料在电化学能量存储和转换中的使用已经变得广泛；然而，在这一领域推进新技术所需的基本理解是缺乏的。这项研究将开发一套实验系统，可以为电化学中的纳米尺度尺寸效应提供基本的热力学理解，特别是在涉及相变的过程中。学生将接受与能量储存和转换相关的技术培训，中学科学教师将获得暑期研究体验。

Professor Daniel A. Buttry of Arizona State University is supported by the Division of Chemistry to study the effect of size and surface stress on the electrochemical properties and phase transformations of metal and metal oxide nanoparticles; in particular, Ag oxidation to AgCl, Pd reduction to PdHx and layered LixMnO2 conversion to spinel LixMn2O4. Methods will be developed for the facile synthesis and size fractionation of Ag, Pd and MnO2 nanoparticles with controlled sizes in the range of 1.5 - 10 nm. The particles will be capped with adenosine triphosphate (ATP) to facilitate their dissolution at high concentration in aqueous supporting electrolytes, thus enabling the study of their electrochemical behavior in thin layer-by-layer films and as individually dissolved nanoparticles. The particles will be subjected to a battery of analytical characterization techniques to determine their sizes and composition. Surface stress will be determined from lattice contraction measurements. The use of nanoscale materials has become widespread in electrochemical energy storage and conversion; however, the basic understanding needed to advance new technologies in this area is lacking. This research will develop a set of experimental systems that can provide a basic thermodynamic understanding of nanoscale size effects in electrochemistry, especially in processes involving phase transformations. Students will be trained in techniques that are relevant to energy storage and conversion, and secondary science teachers will be exposed to a summer research experience.