CAREER: Atomic Scale Study of Reduction of Metal Oxides

该学院早期职业发展(Career)计划奖的目的是阐明金属氧化物还原的原子机制。采用实时原位显微技术(原位超高真空扫描探针显微镜和原位环境透射电子显微镜)，通过时间和空间分辨率的高分辨率成像、衍射和光谱，对氧化物还原的反应形态、结构和化学进行了可控的微观观察。通过真空退火和氢气还原氧化铜(Cu2O和CuO)的简单模型体系的实验，将导致清晰的解释和基本概念的建立。动态原位可视化将与理论建模相结合，以获得对反应活性中心、暂态、传质机制、反应活化能和反应路径的基本见解。该研究将从机理上理解金属氧化物在从成核和生长的初始反应阶段到还原氧化物相宏观增长的后期阶段的还原机理。这项研究的目标是开发一个预测性和层次化的多尺度氧化模型，自然地将氧化物还原的这些不同阶段联系起来。通过开发这样一个预测模型，该项目将对许多实际应用的材料加工产生重大影响，如催化、薄膜生长、燃料反应、气敏和电子器件制造，其中氧化物还原起着关键作用。工程专业的研究生和本科生将通过参与这项研究以及开发一种旨在消除阻碍有效学习电子显微镜的传统障碍的虚拟透射式电子显微镜而受益。高中生和科学教师将被邀请为他们提供第一手的研究经验。

The objective of this Faculty Early Career Development (CAREER) Program award is to elucidate the atomistic mechanism of the reduction of metal oxides. Real-time in situ microscopy techniques (in situ ultrahigh vacuum scanning probe microscopy and in situ environmental transmission electron microscopy) are employed to make controlled microscopic observations of the reaction morphology, structure and chemistry of the oxide reduction by temporally and spatially resolved high-resolution imaging, diffraction, and spectroscopy. Experiments will be performed on the reduction of simple model system of copper oxides (Cu2O and CuO) through vacuum annealing and hydrogen gas, which will lead to clear interpretations and establishment of fundamental concepts. The dynamic in situ visualization will be correlated with theoretical modeling for obtaining essential insights into reaction active sites, transient states, mass transport mechanisms, reaction activation energies, and reaction pathways.The study will lead to mechanistic understanding of the reduction mechanism of metal oxides in the regimes from the initial reaction stages of nucleation and growth to the later-stage macro-scale growth of the reduced oxide phase. The goal of this research is to develop a predictive and hierarchical multi-scale oxidation model that naturally links these different stages of the oxide reduction. Through the development of such a predictive model, the project will have major impact on materials processing for many practical applications such as catalysis, thin film growth, fuel reaction, gas sensing, and electronic device fabrication, where the oxide reduction plays a crucial role. Graduate and undergraduate engineering students will benefit through involvement in the research as well as the development of a virtual transmission electron microscope that is designed to remove conventional barriers hindering effectively learning electron microscopy. High school students and science teachers will be engaged to provide them firsthand research experience.