Development and Applications of Aberration Corrected Environmental STEM (AC ESTEM) for Dynamic In-Situ Reaction Studies of Nanoparticle Catalysts

我们建议在英国创建一个新的研究能力，提供埃分析的温度和连续的气体气氛，而不是通常的高真空控制条件下的动态原位反应研究。新的设计提供了世界上第一个全功能像差校正环境扫描透射电子显微镜（AC ESTEM）。与充满活力的英国化学和能源行业的合作伙伴一起，我们将产生基础应用科学，支持气固反应中使用的基于纳米颗粒的固态多相催化。我们将修改现有的AC TEM/STEM仪器，以补充和扩展气体反应研究国家AC STEM设施的上级图像和高真空中的能量分辨率。它将通过AC STEM用于约克方案和与其他团体的合作项目。它建立在PI在ETEM领域的全球领导地位的声誉之上，迄今为止，全球大部分活动-都是在海外-基于超过10个高分辨率ETEM，其中许多是AC（仅在TEM图像方面），使用作者早期开发的核心技术。初步的“原理验证”已经在约克的远程控制双像差校正JEOL 2200 FS TEM/STEM上得到了验证;结合了亚埃（<0.1 nm）分辨率、不受限制的HAADF Z衬度STEM成像、广角电子衍射和EDX（+ EELS）化学分析，这些都是ETEM上无法提供的。双重像差校正在单个且通常可直接解释的TEM图像中收集接近零散焦的全范围空间频率，以最小化内部界面（例如晶界、外表面、缺陷和其他关键不连续性）处的图像离域。这是特别重要的动态原位研究与不断变化的数据，使不切实际的旧的通过焦点系列重建方法。AC还改变了STEM分析的灵敏度。这项工作将使用分析方法建立与'冷冻'和过程提取的样品，并将其应用于连续过程的研究在新的水平的灵敏度和相关性。获得关键的中间状态和阶段可能是理解和控制过程机制的关键;但它们可能是亚稳态的条件，包括温度或化学环境，因此无法通过异位或脉冲研究。一个非常实际的例子，其中有领先的英国工业界的兴趣和支持，是纳米结构和相关的性能稳定性的负载型金属纳米颗粒非均相催化剂。通过合成、活化、操作、失活、再活化和恢复机制，在基本层面上的理解对于合理管理工业实践以实现持续的活性和选择性至关重要;必要时，在失去这些关键属性时恢复这些属性。该项目的方向与真实的世界学术和工业应用的领域科学需求密切相关，并且具有支持关键技术的早期采用前景，包括延长有用的工艺生命周期。例如，这对于燃料电池更广泛的商业可行性至关重要。该提案得到了充满活力和国际竞争力的化学工业领域的英国领先公司以及学术合作者的支持。与此同时，基础领域科学的新知识也旨在开辟环境中具有紧迫社会价值的新应用。具有战略和战术工业应用的基础物理科学研究导致差异化的知识产品，在英国独一无二，在全球具有充分竞争力。该项目将扩展和应用核心纳米粒子催化科学和技术，并培养一批新的学生，博士后，高级职员和访问者。

We propose to create in the UK a novel research capability providing Angstrom Analysis for dynamic in-situ reaction studies under controlled conditions of temperature and continuous gas atmosphere rather than the usual high vacuum. The new design provides the world's first full function aberration corrected environmental scanning transmission electron microscope (AC ESTEM). In association with partners in the vibrant UK chemical and energy industries we will generate fundamental application science underpinning nanoparticle based solid state heterogeneous catalysis used in gas-solid reactions. We will modify an existing AC TEM/STEM instrument to complement and extend with gas reaction studies the National AC STEM Facility's superior image and energy resolutions in high vacuum. It will be used in York programmes and collaborative projects with other groups through the AC STEM. It builds on the PIs' established reputations for global leadership in ETEM, with most of the worldwide activity to date - all overseas - based on >10 high resolution ETEMs and many of them AC (on the TEM image side only), using core technology from the authors' earlier developments. Preliminary 'proof-of-principle' has been demonstrated on the remotely controlled double aberration corrected JEOL 2200FS TEM/STEM at York; combining sub-Angstrom (<0.1nm) resolution, unrestricted HAADF Z-contrast STEM imaging, wide angle electron diffraction and EDX (+ EELS) chemical analysis not available on ETEMs. The double aberration correction collects, in a single and often directly interpretable TEM image, a full range of spatial frequencies at close to zero defocus to minimise image delocalisation at internal interfaces such as grain boundaries, external surfaces, defects and other key discontinuities. This is especially important for dynamic in-situ studies with continuously changing data making impractical older through-focal series reconstruction methods. AC also transforms the sensitivity of STEM analysis. The work will use analytical methods established with 'frozen' and process extracted samples, and apply them to the study of continuous processes at new levels of sensitivity and relevance. Access to key intermediate states and phases may be critical to understand and control process mechanisms; but they may be metastable with respect to conditions, including temperature or chemical environment, and therefore not accessible through ex-situ or pulse studies. A very practical example, in which there is leading UK industry interest and support, is the nano-structure and related property stability of supported metal nanoparticle heterogeneous catalysts. Through synthesis, activation, operation, deactivation, reactivation and recovery mechanisms, understanding at a fundamental level is critical for managing on a rational basis industrial practice for sustained activity and selectivity; and where necessary recovering these key attributes when lost. The project direction is closely aligned with the domain science needs of real world academic and industrial applications, and there are early adoption prospects for underpinning key technologies; including to extend useful process life cycles. For example, this is critical for the wider commercial viability of fuel cells. The proposal has the support of leading UK companies in the vibrant and internationally competitive chemical industry sector, and of academic collaborators. At the same time, the new learnings in basic domain science are also directed towards opening up new applications of pressing societal value in the environment. Fundamental physical science research with strategic and tactical industrial applications leads to differentiated intellectual products with an initiative unique in the UK and fully competitive globally. The project will extend and apply core nanoparticle catalysis science and technology, and train a new cohort of students, postdocs, senior staff and visitors.