Dynamical Response of Catalytic Systems in a CS Corrected Environmental Transmission Electron Microscope

In industrialized countries, 85-90 % of chemical production involves catalytic processes [1]. It has been estimated that 35 % of global GDP depends critically on the use of catalysis [2]. Transmission electron microscopy (TEM) has been used extensively in catalysis research [3]. However, in contrast to chemical reactors, a conventional TEM is a high vacuum tool. Thus, observations do not always reflect the active state of materials. Environmental TEM (ETEM) provides the capability to expose samples to a gas atmosphere during imaging and analysis. Even though the gap between reactor and high-vacuum pressures has not been fully bridged, progress has been made towards observing materials in their working environment. Many catalytically active materials consist of metals or metal alloys, which are deposited onto a support material as nanoparticles to optimize the exposed active surface area. In a catalytic reactor, the particles tend to sinter under reaction conditions resulting in the formation of larger particles and a loss of catalytic activity. Several models of sintering in different systems have been put forward [4,5]. However, most investigations have been post mortem studies, revealing only the final state of the catalyst. For fundamental studies of sintering, we used a model system consisting of gold nanoparticles on