CAREER: Atomic Scale Study of Reduction of Metal Oxides

这个教师早期职业发展（CAREER）计划奖的目的是阐明金属氧化物还原的原子机制。 实时原位显微镜技术（在原位真空扫描探针显微镜和原位环境透射电子显微镜）进行控制的微观观察的反应形态，结构和化学的氧化物还原的时间和空间分辨的高分辨率成像，衍射和光谱。 通过真空退火和氢气还原简单的氧化铜模型体系（Cu2O和CuO）进行实验，这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模型相结合，获得对反应活性位点、瞬态、传质机制、反应活化能和反应途径的基本认识，从而从机理上理解金属氧化物从成核和生长的初始反应阶段到还原氧化物相的后期宏观尺度生长的还原机理。 本研究的目标是开发一个预测和分层的多尺度氧化模型，自然地连接这些不同阶段的氧化物还原。 通过开发这样的预测模型，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，气体传感和电子器件制造，其中氧化物还原起着至关重要的作用。 研究生和本科工程专业的学生将通过参与研究以及虚拟透射电子显微镜的开发而受益，该显微镜旨在消除阻碍有效学习电子显微镜的传统障碍。 高中学生和科学教师将参与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.