Probing surface-molecule interactions of perovskite catalysts

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.

Catalysts are important in production of fuels, reduction of economically harmful combustion products, and are generally beneficial to the chemical industry for applications concerning energy and the environment. According to the EPSRC strategic goals "The first step in delivering impact is to sponsor excellent research in areas of national importance". Further, EPSRC has explicitly identified catalysts, which fall under its Energy and the Manufacturing the Future Challenge themes, as an area of national importance.

The insights sought via the research proposed here have the potential to improve the activity of existing catalysts and also create new opportunities for prototyping innovative, next-generation materials for catalysts. Specifically, the utilisation of the relatively new methodology of in situ TEM that is proposed for this research project has the potential to transform our understanding of the behaviour of catalytic surfaces when exposed to different molecules, with direct implications for compositional and microstructural control of nano-catalysts with tailored properties.

The collaboration of leading international institutions like MIT and BNL with a leading UK institution, IC, will contribute to academic advancement towards addressing the globally important issue of new materials for energy and environmental applications. This multi-disciplinary project, embracing materials science, chemistry, microscopy, and surface engineering, will also enhance the application of knowledge transfer through open access to materials (MIT & IC), facilities (BNL), theoretical calculations (IC), and data interpretation (all institutions).

A significant part of the impact of the proposed project involves the dissemination of results to high profile national and international conferences. For example, the MRS spring meeting has three symposia. Two of them are in parallel path to the proposed research: one is dedicated to materials for energy applications and one is assigned to the emerging field of in situ characterisation techniques. This emphasises again the global importance of the work of the proposed project. Attendance to meetings like MRS and publication of the work to high-impact journals will aid the global discussion of new pathways to synthesis and characterisation of catalytic nanostructures.