Fig. 2: Structural characterizations of the evolution from the Fe3O4 nanocube to the Fe3O4@χ-Fe5C2 nanocube.
From: Facet sensitivity of iron carbides in Fischer-Tropsch synthesis
a Schematic of the major steps involved in the continuous evolution from the Fe3O4 nanocube to the Fe3O4@χ-Fe5C2 nanocube. I refers to the reduction process; II refers to the corner carburization and oxidation; III refers to the surface carburization, O migration, and bulk oxidation; IV refers to the surface balanced carburization and oxidation. b HAADF-STEM images of an individual Fe3O4 nanocube. c HAADF-STEM images of an individual Fe nanocube. d–f HAADF-STEM images of an individual nanocrystal after the treatment of Fe nanocubes with syngas for 2, 5, and 10 h, respectively.
