In situ structural analysis of crystalline Fe–Mo–C nanoparticle catalysts during the growth of carbon nanotubes

We show that image simulation is invaluable for the interpretation of time-dependent environmental transmission electron microscopy (ETEM) images. Experimental ETEM images of a crystalline nanoparticle catalyst (NPC) during the growth of carbon nanotubes were compared with simulated images of the Fe21Mo2C6 structure that was observed along various directions. Lattice images that appear in the NPC at different times can be accounted for by considering only the Fe21Mo2C6 structure.

► In situ high-resolution environmental transmission electron microscopy (ETEM) in gas. ► Structural fluctuation of nanoparticle catalysts (NPCs) with time. ► Instantaneous ETEM images of NPCs were analyzed by image simulation. ► Lattice images appearing in NPCs can be accounted for with only Fe21Mo2C6 structure. ► These results show that ETEM is an acceptable method to study dynamic reactions.