Present status and future prospects of environmental HVEM for nanomaterials
Professor Nobuo Tanaka, Nagoya University, Japan
Environmental transmission electron microscopy (E-TEM) attracts a strong interest of materials scientists, particularly, those of batteries and catalysts, because the actual chemical reaction processes in gases and liquids should be clarified in real space and in atomic level. E-TEM observations of thick samples also become important for cutting-edge materials in practical use. 3D observation is also necessary for clarifying morphologies of practical catalysts.
Professor Tanaka and colleagues have developed 1MV TEM/STEM equipped with an open-type environmental cell which enables observations in 100 Torr of hydrogen, oxygen, nitrogen and carbon mono-oxide(CO) gases, named 'Reaction Science HVEM'(RSHVEM).
In this talk, Professor Tanaka would like to present new data obtained by the instrument such as (1) in-situ observation of porous gold catalysts, whose inner surfaces with zigzag atom arrangement enhance oxidation of CO gas, (2) observation of diesel soot oxidized in air, and (3) in-situ observation of fractures related to 'hydrogen brittleness' for a Cu/Si interface and grain boundaries in Ni3Al alloys. Observation of lithium battery materials is also available using a non-exposure transfer holder as well as QMAS ability. Finally, advantages and future prospects of E-HVEM are discussed.
Atoms in action for energy, healthcare and environment using atomic resolution environmental (S)TEM: advancing the frontiers of chemical research
Professor Dame Pratibha Gai FREng FRS, University of York, UK
Many heterogeneous chemical reactions utilise gas-solid catalyst reactions at elevated temperatures and they play a pivotal role in the production of energy, healthcare, pollution control and food. The dynamic catalytic chemical reactions take place at the atom level. Understanding atomic structure evolution and the ensuing catalyst function are vital to developing novel materials and improved chemical processes. However due to limitations of the instrumentation these atomic processes were not well understood. The development of the first atomic resolution-Environmental Transmission Electron Microscope (atomic resolution-ETEM) [Boyes and Gai, Ultramicroscopy 67 (1997) 197], enables the visualisation and analysis of gas-solid catalyst reactions at the atomic level leading to key discoveries and the development is used globally. The ETEM has been advanced to analytical environmental scanning TEM (ESTEM) with single atom resolution and full analytical capabilities. Novel E(S)TEM imaging and analysis in real-time in controlled real-world reaction environments reveal single atom dynamics in fuel cell catalysts, fuels including sustainable biofuels, healthcare applications and ammonia synthesis for agricultural products in food production. The development of a liquid holder enables imaging and analysis of chemical reactions in liquid environments. The dynamic studies, in combination with chemical methods, provide unique insights into atoms in action and atomic scale reaction pathways in chemical reactions, opening new opportunities for the control of the dynamic atomic structure for beneficial catalytic and functional properties. Smarter synthesis leading to improved materials and processes with significantly enhanced performance are possible. Benefits include new knowledge and cleaner processes for renewable energy and healthcare as well as improved or replacement mainstream technologies in the chemical and energy industries.
Seeing is believing: atomic-scale imaging of catalysts under reaction conditions
Professor Irene Groot, Leiden University, The Netherlands
The atomic-scale structure of a catalyst under reaction conditions determines its activity, selectivity, and stability. Recently it has become clear that essential differences can exist between the behaviour of catalysts under industrial conditions (high pressure and temperature) and the (ultra)high vacuum conditions of traditional laboratory experiments. Differences in structure, composition, reaction mechanism, activity, and selectivity have been observed. These observations made it clear that meaningful results can only be obtained at high pressures and temperatures. Therefore, the last years have seen a tremendous effort in designing new instruments and adapting existing ones to be able to investigate catalysts in situ under industrially relevant conditions.
In this talk, Professor Groot will give an overview of the in situ imaging techniques the group uses to study the structure of model catalysts under atmospheric pressures and elevated temperatures. The group has developed set-ups that combine an ultrahigh vacuum environment for model catalyst preparation and characterisation with a high-pressure flow reactor cell, integrated with either a scanning tunneling microscope or an atomic force microscope. With these set-ups the group is able to perform atomic-scale investigations of well-defined model catalysts under industrial conditions. Additionally, they combine the structural information from scanning probe microscopy with mass spectrometry measurements. In this way, the group can correlate structural changes of the catalyst due to the gas composition with its catalytic performance. Furthermore, they use other in situ imaging techniques such as transmission electron microscopy, surface X-ray diffraction, and optical microscopy, all combined with mass spectrometry.
Micro to macro-scopic in vivo imaging including magnetic resonance imaging: using advanced medical imaging technologies as a ‘macroscope’ to determine pathophysiologies of complex human brain diseases
Professor Joanna Wardlaw CBE FMedSci, University of Edinburgh and NHS Lothian, UK
The rapid advances in understanding and treatment of common human brain diseases have (arguably) been made possible by advances in development of in vivo diagnostic imaging technologies in the last few decades. The human brain is complex, with no truly comparable model species, limiting the ultimate clinical value of many rodent models. Advances in non-invasive medical imaging technologies particularly magnetic resonance imaging, mean that detailed data on brain structure and function and pathological changes in disease can now be determined and tracked in large human samples including population studies and disease cohorts. However, these methods also have limitations of resolution, and tissue often only becomes available post mortem, reflecting end stage disease. Hence, to tackle a complex disorder that develops insidiously in life requires a multimodal approach that includes in vivo MRI and related ‘macroscopic’ methods in patients and volunteers, and parallel and complementary microscopic methods applied to post-mortem brain tissue and in vivo and in vitro static and dynamic imaging methods in rodent models such as MRI, 2-PI, histological and electron microscopic methods. This lecture will illustrate these principles using the example of cerebral small vessel disease, a major cause of both stroke and dementia and of ageing-related multimorbidities.
Modelling the structures of crystals and nano-particles
Professor Richard Catlow FRS, University College London, UK