Environmental Transmission Electron Microscopy (ETEM) Studies of Single Iron Nanoparticle Carburization in Synthesis Gas

Structuralevolution of iron nanoparticles involving the formationand growth of iron carbide nuclei in the iron nanoparticle was directlyvisualized at the atomic level, using environmental transmission electronmicroscopy (TEM) under reactive conditions mimicking Fischer–Tropschsynthesis. Formation of the iron carbide nuclei and surface reconstructionof the iron nanoparticle play an essential role in carburization ofthe iron nanoparticle and consequent formation of Fe₅C₂. Identification of carbide and oxide intermediates evidencedby high-resolution TEM images, electron diffraction patterns and electronenergy-loss spectra provides a detailed picture from initial activationto final degradation of iron under synthesis gas.