Reflections on the value of electron microscopy in the study of heterogeneous catalysts

Abstract

Electron microscopy (EM) is arguably the single most powerful method of characterizing heterogeneous catalysts. Irrespective of whether they are bulk and multiphasic, or monophasic and monocrystalline, or nanocluster and even single-atom and on a support, their structures in atomic detail can be visualized in two or three dimensions, thanks to high-resolution instruments, with sub-Ångstrom spatial resolutions. Their topography, tomography, phase-purity, composition, as well as the bonding, and valence-states of their constituent atoms and ions and, in favourable circumstances, the short-range and long-range atomic order and dynamics of the catalytically active sites, can all be retrieved by the panoply of variants of modern EM. The latter embrace electron crystallography, rotation and precession electron diffraction, X-ray emission and high-resolution electron energy-loss spectra (EELS). Aberration-corrected (AC) transmission (TEM) and scanning transmission electron microscopy (STEM) have led to a revolution in structure determination. Environmental EM is already playing an increasing role in catalyst characterization, and new advances, involving special cells for the study of solid catalysts in contact with liquid reactants, have recently been deployed.

In situ and operando electron microscopy in heterogeneous catalysis—insights into multi-scale chemical dynamics

“…In addition, the interaction of the electron beam with the sample generates spectroscopic signatures that can be used for complementary chemical analysis. This combination of high spatial resolution and spectroscopic capabilities make EMs ideal for studying the structure of nanoscale catalysts, especially those that consist of metal NPs [125][126][127][128]. For instance, TEM images are often the only way to establish local structures in these materials (examples in Figure 3), especially in the case of single-atom catalysts [129].…”

Microscope in Dentistry: A Review Article

“…In REM, the reflected beam of elastically scattered electrons is detected. It is used for looking at the microstructure of magnetic domains [137][138][139].…”

Recent Progress on Revealing 3D Structure of Electrocatalysts Using Advanced 3D Electron Tomography: A Mini Review

“…3D electron tomography helps reveal the nanostructures in 3D, and thus contributes to activity and degradation study for electrocatalysis ( Hungría et al, 2019 ; Hovden and Muller, 2020 ). Despite much progress has been achieved in studying catalysts and related nanomaterials by using 3D electron tomography ( Zečević et al, 2013 ; Thomas, 2017 ; Zhang et al, 2017 ; Hungría et al, 2019 ), a dedicated review of electrocatalysts’ investigation by 3D electron tomography is lacking. Therefore, in this mini-review, we summarize recent applications of electron tomography towards the developments of electrocatalysts.…”