In‐situ Transmission Electron Microscope Techniques for Heterogeneous Catalysis

Abstract

The physicochemical properties of heterogeneous catalysts in static or inert environments often deviate greatly from the properties under in‐situ or working conditions. To gain an insightful understanding of realistic catalyst properties and the corresponding catalytic mechanisms, it is essential to identify and rationalize changes in catalysts under reaction conditions. In recent years, in‐situ transmission electron microscope (in‐situ TEM) techniques have been increasingly developed, offering a unique approach to visualize the evolution of heterogeneous catalysis with ultra‐high spatial resolution, good energy resolution and reasonable temporal resolution under controllable or even realistic catalytic conditions. In this review, we have summarized recent advances in the in‐situ TEM analysis of heterogeneous catalysis, which suggests the great potential of this technique in this important field. Furthermore, technical challenges and possible solutions are discussed.

Stability of Cobalt Particles In and Outside HZSM‐5 under CO Hydrogenation Conditions Studied by ex situ and in situ Electron Microscopy

“…Alternatively, by using closed gas cell nanoreactors it is possible to perform operando TEM measurements at 0.1–5 bar. Compared to ETEM this method involves even more challenging sample preparation as the sample has to be positioned inside the nanoreactor [33–35] . In both cases catalyst behavior in a model operating environment can be examined.…”

“…They detected a build‐up of carbon layers on the cobalt surface at higher temperatures (400–450 °C) due to CO disproportionation. Although ETEM studies are typically limited to a low pressure range and there is a gap in the experiment duration, it can provide an important complementary insight into deactivation to operando studies as it allows to monitor changes at the atomic scale [33] . Additionally, the capability of in situ TEM to track the time dependent evolution of individual particles under model conditions is complementary to ex situ TEM providing cumulative information after exposure to technicaly‐relevant conditions.…”

Assessing the Effect of the Electron‐Beam Irradiation on Pd/Ga2O3 Catalyst under Ambient Pressure

“…The impact of electron‐beam irradiation damage in gas and chemical processes should be eliminated by using appropriate experimental conditions, otherwise the in‐situ TEM experiments may lead to ambiguous conclusions . Aiming to reveal the structural information that directly relates with catalytic activity, the effect of electron‐beam irradiation needs to be studied systematically . Using low electron current density and avoiding the accumulation of high dose are necessary for in‐situ TEM experiments .…”

Quo Vadis Micro-Electro-Mechanical Systems for the Study of Heterogeneous Catalysts Inside the Electron Microscope?

“…These advances have contributed to a Dedicated to Prof. Dr. Norbert Kruse on the occasion of his 70th birthday. significant growth of scientific contributions in the field of in situ TEM for catalysis, as evidenced by the large number of review articles that have been published recently [7][8][9][10][11][12][13][14]. A chronological summary of the combined MEMS and in situ TEM developments can be found in Fig.…”

“…In addition, we will critically discuss existing challenges of such in situ TEM experiments. As in situ TEM applications have already been the subject of several reviews [7][8][9][10][11][12][13][14], we will focus on the design and materials of MEMS themselves. We discuss the relevance of the kinetics in gas cells, with regard to the discrepancies between these nanoreactors and fixed bed reactors (FBR).…”