Fig. 4. Catalytic performance of different iron catalysts.

a Comparison of FTY values between ε-Fe₂C@graphene catalyst and iron catalyst loaded on active carbon with different iron loadings. b Long-term stability of ε-Fe₂C@graphene and un-encapsulated χ-Fe₅C₂ catalysts. Reaction conditions: H₂/CO = 1/1, 573 K, p = 10 bar. The insert shows the high-resolution TEM micrograph for the spent ε-Fe₂C@graphene catalysts after 400 h reaction. Scale bar, 5 nm.