Enhancing CO Activity and Reducing CH4 Formation of Fe3C by Graphene Oxide during Syngas Conversion

The Fischer−Tropsch synthesis (FTS), the key industrial process for the transformation of syngas into valuable chemicals and clean fuels, benefits from advanced catalyst design. Iron carbide nanoparticles (Fe 3 C) and their graphene oxide-derived counterpart (Fe 3 C/Graphene) were successfully synthesized. Fe 3 C/Graphene exhibits a large specific surface area, high pore volume, and abundant surface defective sites provided by the reduced graphene oxide support. Together with the stabilized Fe 3 C active phase, these features promote CO activation and C−C coupling, leading to enhanced CO conversion, higher C 5+ selectivity, and suppressed CH 4 formation comparedwith Fe 3 C. Density functional theory calculations reveal that the improved CO activation on Fe 3 C/Graphene originates from reduced electron transfer and weakened Fe−C and C−O bonds. For Fe 3 C, the rate-determining step is CO* + H* → CHO*, whereas for Fe 3 C/Graphene, the rate-determining step is CHO* → CH* + O*. It also reveals that Fe 3 C/Graphene accelerates this step, corroborating the enhanced CO activation observed experimentally. Furthermore, the simulations confirm that defective graphene significantly raises the effective barrier for methanation, perfectly rationalizing the suppressed CH 4 formation. These findings demonstrate that the introduction of graphene oxide is a effective strategy for tailoring the catalytic performance of Fe-based FTS catalysts.