Probing surface-molecule interactions of perovskite catalysts

发展可再生能源生产和储存技术是当今的主要挑战之一。合成高效、高活性和低成本的催化剂用于电化学能量转换过程，如氧还原过程，是国际上感兴趣的一个重要研究领域。为此，该项目旨在了解在功能性钙钛矿颗粒和薄膜中发生的催化过程的基本原子尺度机制。这些结构在磁性传感器和自旋电子学等方面的应用是众所周知的，但最近的研究也揭示了在碱性燃料电池(AFC)中促进氧还原(或放氧取决于氧化物材料)的良好催化活性。这为AFC技术的商业化提供了一个很好的机会，因为这些氧化物，如LaMnO3，比起贵金属，如常用的铂，显示出显著的经济优势。阻碍其商业化的制约因素是高活性氧化物催化剂的开发。因此，对合成具有定制性质的功能氧化物薄膜和颗粒的需求越来越大，需求集中在表征方法的开发和应用上，以实时探测催化过程。为了解决这一问题，将采取一种涉及化学、材料科学和显微镜的跨学科方法。运载工具将是环境透射电子显微镜(ETEM)。ETEM是一种专门的仪器，能够提供高分辨率成像，就像传统的透射电子显微镜一样，另外还有一个好处，就是样品腔内的气体压力升高，最高可达大气压力的几个百分点。在实践中，催化剂颗粒(和薄膜)可以在暴露在氧气或水等气体环境中时在原子尺度上成像，模拟真实的燃料电池条件。通过这种方式，最终决定每个催化剂活性的表面化学反应可以被实时监测，并具有原子尺度的精度。

Developing renewable energy production and storage technologies represents one of the major challenges nowadays. The synthesis of efficient, highly active, and cost-effective catalysts for use in electrochemical energy conversion processes, such as the oxygen reduction process, is a critical area of research with international interest. To this end, this project aims to the understanding of the fundamental, atomic-scale mechanisms of catalytic processes as they occur in functional perovskite particles and thin films. These structures are well known for applications such as magnetic sensors and spintronics, but recently studies have also revealed promising catalytic activity that facilitates oxygen reduction (or oxygen evolution depending on the oxide material) in alkaline fuel cells (AFCs). This presents a great opportunity for commercialisation of AFC technology, since these oxides, such as LaMnO3, exhibit a significant economic advantage over noble metals, such as the commonly used Pt. The inhibiting factor that prevents their commercialisation is the development of highly active oxide catalysts. Thus, the need for synthesis of the functional oxide thin films and particles with tailored properties is growing immensely, and the demand is focused on the development and application of characterisation methods to probe the catalytic processes in real time. To address this, an interdisciplinary approach engaging chemistry, materials science, and microscopy will be undertaken. The vehicle will be environmental transmission electron microscopy (ETEM). ETEM is a specialised instrument that is capable for delivering high-resolution imaging, as in conventional transmission electron microscopy, with the extra benefit of elevated gas pressures in the sample chamber, as high as a few per cent of atmospheric pressure. In practice, the catalyst particles (and thin films) can be imaged at atomic-scale level while exposed to gas environments, such as oxygen or water, simulating real fuel cell conditions. This way, the chemical reactions at the surfaces, which ultimately determine each catalyst's activity, can be monitored in real time and with atomic scale precision.