Progress in surface sciences of iron carbide-based model catalysts

Fe-based catalysts have the advantage that they are cheap and have favorable selectivity, with a low H2/CO ratio in Fischer-Tropsch synthesis. The active phase in iron-based Fischer-Tropsch synthesis catalysts has long been under debate, increasing evidences suggest that iron carbide is the key structure in the catalytic reaction. Since the structural evolution of iron carbide involves atomic-scale reconstruction, carbon diffusion, and changes in surface electronic states, traditional characterization methods for powdered catalysts struggle to provide in-situ and detailed structural information. In recent years, model catalytic systems constructed and characterized through surface science research methods have offered new avenues for exploring the structural characteristics, formation mechanisms, and reaction pathways of iron carbide. This review systematically discusses the work of Fe carbide films grown on carriers such as Au, Cu, Si, SiO2, and on Fe single crystal surfaces in recent years, the main progress and key conclusions of fundamental research on iron-based catalysts for Fischer-Tropsch synthesis using surface science technologies.