CAREER: Engineered Oxide Heterointerfaces With Tunable Vacancy Distributions

非技术描述：许多能量转换和存储应用需要沿某些关键表面或界面的化学反应才能有效运行。用丰富、廉价、高效的复杂金属氧化物替代品取代稀有、昂贵的贵金属材料仍然是能源转换面临的主要挑战。这些替代氧化物材料的结构中缺失的氧原子决定了它们的功能特性。这项研究使用新的显微方法和经典的半导体分析来实时可视化和量化在实际能量转换系统的操作条件下跨临界界面的缺失氧原子的位置和数量。了解缺失原子如何影响界面能量转换的基本机制，对于快速推进燃料电池和电解槽等设备的发展至关重要。这项工作培养材料科学、表面科学和电化学学科的本科生和研究生，以便在能源转换/储存、电子和纳米技术部门就业。该项目还包括一个完全整合的教育部分，其中一个本科生团队开发显微镜模块，在高级课程和研究生课程中使用便携式原子力显微镜进行演示。这种翻转的教学模式还允许本科生团队将他们的模块演示扩展到夏季高中项目，并在社交媒体上激励未被充分代表的群体将科学和工程作为令人兴奋和有价值的学术和职业道路。技术细节：氧空位介导的还原、解离或合并机制通常有助于固态电化学能量转换过程中的速率决定步骤。该项目将变革性的原位扫描探针显微镜方法与静电分析相结合，在纳米尺度上直接观察和量化在极端环境扰动下通过电活性氧化物界面的关键高温空位介导的离子传输现象。这项研究的目的是了解电活性氧化物界面上的空位分布是如何作为功函数工程、失配应变和/或成分梯度的函数而演变的。这些活动对大学生研究人员进行了高温原位显微镜和样品制备方面的培训，以推动实验方法学的前沿。通过实时直接观察电子陶瓷界面上的空位再分布，该项目正在建立实现机械稳定、催化活性界面和推进下一代电化学能量转换系统所需的结构-性能原则。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL DESCRIPTION: Many energy conversion and storage applications require chemical reactions along some critical surface or interface to effectively operate. Replacing scarce, expensive noble-metal materials with abundant, cheap, efficient complex metal-oxide alternatives remains a primary challenge facing energy conversion. Missing oxygen atoms in the structure of these alternative oxide materials dictate their functional properties. This research uses novel microscopy methods and classic semiconductor analysis to visualize and quantify the location and amount of missing oxygen atoms across the critical interface under the operating conditions of actual energy conversion systems, in real time. Understanding the fundamental mechanisms of how missing atoms affect energy conversion at the interface is vital to rapidly advancing the development of devices such as fuel cells and electrolyzers. This work trains undergraduate and graduate students across the disciplines of materials science, surface science, and electrochemistry for placement in the energy conversion/storage, electronics, and nanotechnology sectors. This project also includes a fully integrated educational component where an undergraduate student team develops microscopy modules that are demonstrated in both senior capstone and graduate level courses using a portable atomic force microscope. This "flipped" instruction model also allows the undergraduate team to extend their module demonstrations to summer high school programs, and on social media, to inspire underrepresented groups to pursue science and engineering as exciting and worthwhile academic and career pathways.TECHNICAL DETAILS: Oxygen vacancy-mediated reduction, dissociation, or incorporation mechanisms often contribute to the rate-determining step in solid-state electrochemical energy conversion processes. This project combines transformative in situ scan probe microscopy methods with electrostatic analysis to directly observe, and quantify, critical high temperature vacancy-mediated ionic transport phenomena across electroactive oxide interfaces under extreme environmental perturbation, at the nanoscale. The goal of this research is to understand how vacancy distributions evolve across electroactive oxide interfaces as a function of work function engineering, mismatch strain, and/or compositional gradients. These activities train university student researchers in high temperature in situ microscopy and sample preparation to push the frontier of experimental methodology. By directly observing vacancy redistribution across electroceramic interfaces in real time, this project is establishing the structure-property principles necessary for the realization of mechanically-stable, catalytically-active interfaces and advancement of next-generation electrochemical energy conversion systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.