Corrosion of Nanoscale Alloy Electrodes

技术概述：本研究项目研究纳米级结构中合金的腐蚀过程。该项目采用实验和理论相结合的方法，专注于开发广泛适用的合金腐蚀热力学模型。这个问题非常丰富，因为必须考虑两个固有的长度尺度。一种长度刻度由合金成分确定，另一种由样品的物理尺寸确定。问题的丰富性源于这些长度尺度的相互作用，这导致了全新的腐蚀现象。这种结构的腐蚀在单层水平上是重要的，并且发生在相应的宏观尺度样品中不易受攻击的成分上。因此，表征合金腐蚀的传统方法在纳米尺度上是不适用的。为了完成这项工作，我们使用了一种新技术来开发尺寸范围为3 ？采用多种表征技术，包括用于分析表面成分的欠电位沉积，电化学扫描隧道显微镜和高分辨率分析透射电子显微镜。将纳米结构的实验数据与我们的热力学模型相结合，将为理解这些重要的纳米级腐蚀过程提供一个基本的框架。从这项研究中发展出来的科学将影响纳米技术的各种应用。非技术摘要：本研究考察了纳米级结构的腐蚀，如用作燃料电池催化剂的纳米结构、基于纳米颗粒的生物检测、生物传感和用于安全与监视的环境监测。在运输动力燃料电池中，金属合金催化剂颗粒对腐蚀的稳定性是关键问题，迄今为止限制了该技术的广泛应用。这个项目正在发展新的实验数据和模型，为设计耐腐蚀的纳米级结构提供工程指导。为了实现这些目标，学生们接受培训，发展专业知识，以整合电化学和材料科学学科的知识。如今，在美国以这种方式培养的研究生非常匮乏。这个问题的部分原因是学生们认为腐蚀科学是一个古老的发达领域，与当前的热点领域（包括可再生能源和生物纳米等领域）是分开的。该研究项目为腐蚀科学开辟了一个新的领域，将有助于培养更多对腐蚀感兴趣的高素质学生。为了支持这一点，我们正在开发新的材料电化学课程，特别关注纳米电极的腐蚀和电化学行为。该课程将在本科高年级/研究生初级阶段教授，旨在激发学生对该领域的兴趣。研究生和本科生都参与了这个研究项目。除了积极参与国家科学基金会资助的少数民族研究生教育@山州联盟（MGE@MSA）项目外，PI还让来自代表性不足的群体的个人参与到这个研究项目中来。

TECHNICAL SUMMARY:This research project examines alloy corrosion processes in nanoscale structures. The program involves a combined experimental and theoretical approach focused on developing broadly applicable thermodynamic models of dealloying corrosion. This problem is extraordinarily rich in that there are two intrinsic length scales that must be considered. One length scale is set by the alloy composition and the other is set by the physical dimensions of the sample. The richness of the problem derives from the interaction of these length scales, which leads to entirely new corrosion phenomena. Corrosion of such structures is important at monolayer levels and occurs at compositions which are not vulnerable to attack in corresponding larger macroscopic scale samples. Thus conventional approaches for characterizing dealloying corrosion are not applicable at the nanoscale. In order to perform this work we use a new technique for developing reproducible alloy nanoelectrodes in the size range of 3 ? 10 nm and employ a variety of characterization techniques including underpotential deposition for assaying surface compositions, electrochemical scanning tunneling microscopy and high resolution analytical transmission electron microscopy. The combination of experimental data generated on well characterized nanostructures together with our thermodynamic modeling will provide a general fundamental framework for understanding these important nanoscale corrosion processes. The science evolving from this research will impact diverse applications in nanotechnology.NON-TECHNICAL SUMMARY:This research examines corrosion of nanoscale structures such as those used as catalysts in fuel cells, nanoparticle based bio-assays, bio-sensing and environmental monitoring for security and surveillance. In the case of fuel cells for transportable power the stability of metal alloy catalyst particles to corrosion is the key problem and to date has limited this technology to widespread application. This program is evolving new experimental data and modeling that will provide engineering guidelines for the design of nanoscale structures that are stable to corrosion. In order to accomplish these goals students are trained to develop expertise in order to integrate knowledge in the disciplines of electrochemistry and materials science. Today there is a dearth of graduate students trained in the U.S. in this manner. Part of this problem stems from the perception students have that corrosion science is an old developed field and is separated from the current hot areas which include fields such as renewable energy and ?bio-nano?. This research program opens a new arena in corrosion science which should help to get more high quality students interested in corrosion. In support of this, we are developing new courses in materials electrochemistry which specifically focuses on the corrosion and electrochemical behavior of nanoelectrodes. This will be taught at the senior undergraduate/beginning graduate level and is aimed specifically at exciting student interest in this field. Both graduate and undergraduate students are involved in this research program. In addition to active involvement with the NSF funded Minority Graduate Education @ Mountain State Alliance (MGE@MSA) program, the PI is getting individuals from underrepresented groups involved in this research program.