Effects of the Encapsulation Membrane in Operando Scanning Transmission Electron Microscopy

Abstract

Nanoscale tailoring of catalytic materials and Libattery alternatives has elevated the importance of in situ gas-phase electron microscopy. Such advanced techniques are often performed using an environmental cell inserted into a conventional S/TEM setup, as this method facilitates concurrent electrochemical and temperature stimulations in a convenient and costeffective manner. However, these cells are made by encapsulating gas between two insulating membranes, which introduces additional electron scattering. We have evaluated strengths and limitations of the gas-phase E-cell S/TEM technique, both experimentally and through simulations, across a variety of practical parameters. We reveal the degradation of image quality in an E-cell setup from various components and explore opportunities to improve imaging quality through intelligent choice of experimental parameters. Our results underscore the benefits of using an E-cell STEM technique, due to its versatility and excellent ability to suppress the exotic contributions from the membrane device.

Direct Observation of Sample Dynamics in the Gaseous Environment: A Perspective on Current Trends and Future Directions of In Situ Gas Cell Transmission Electron Microscopy

“…It has been already found that reducing the thickness of these membranes or substituting the material can improve the image resolution. 20 When innovative developments are contemplated, many avenues can be considered. Previously we depicted the importance and the use of residual gas analyzer systems in several in situ ETEM studies.…”

“…The SiN x membranes incorporated in this setup trigger additional electron scattering, resulting in a reduction of the resolution. It has been already found that reducing the thickness of these membranes or substituting the material can improve the image resolution …”

“…This acts as a limitation as such modifications would be costly due to the need for separate instruments for different types of TEM analyses. 19,20 In Situ (E)TEM Using Closed Cell or Windowed Gas Cell System. With the drawbacks of the DP systems as discussed above, another approach to conducting in situ atmospheric TEM has been developed, known as the windowed gas cell or the closed gas cell system, which, thanks to its versatility and convenience, has revolutionized ETEM research, taking it from a niche area to one that is rapidly becoming more accessible (Figure 1).…”

“…Another advantage is that the electron beam hits the sample without passing through any physical barrier as compared to the closed cell (discussed later), therefore resulting in maximum instrumental image resolution best suitable for lighter elements. Moreover, the energy-dispersive X-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS) signal detection capabilities are better in the case of DP-ETEM experiments, as there is no hindrance to the electron transparency by silicon nitride membranes and windowed architecture as in the gas cell holder. − Due to these factors, the DP-ETEM system is still being used in various experiments. Some recent work is discussed below.…”

“…Finally, these systems can be only used in dedicated ETEMs as the TEM column needs to be modified to be able to accommodate the gaseous environment. This acts as a limitation as such modifications would be costly due to the need for separate instruments for different types of TEM analyses. , …”