It has been a challenge in transmission electron microscopy (TEM) to study chemical processes, for instance, at gas–solid interfaces in situ with atomic spatial resolution [1–6]. Modern in-situ TEM observations of chemical processes has been performed during exposure to gases at ambient pressures and elevated temperatures in environmental TEMs (ETEMs). This analysis can be carried out in ambient operating environment in various fields, such as heterogeneous catalysis, electrochemistry, nanofabrication, materials science and biology.
Creemer et al.  reported that a nanoreactor enabled high-resolution ETEM of nanomaterials during exposure to heat and gases at ambient pressure.
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