Structural patterns in carbon chemisorption on ultrasmall iron clusters: A first-principles study

Abstract

To get a better understanding of the catalyst chemistry of iron clusters, four representative Fen (n = 1–4) clusters were chosen to systematically investigate the carbonization processes through subsequently adding carbon atoms by using density functional theory calculations. With respect to the quantum results, the analysis of structures, stabilities, and magnetic moments were conducted. It is found that there are three typical peaks of the chemisorption energies for all the clusters studied during the carbonization processes. The third type of peaks is the adsorption energies of critical structures that indicate the formations of the typical long carbon chains. These structures contain 10, 13, 14, and 17 carbon atoms corresponding to Fe1, Fe2, Fe3, and Fe4 pure clusters, respectively, which generate different numbers of carbon chains with the varying lengths. Furthermore, the total magnetic moments of four pure iron clusters would be reduced by the formations of FeC bonds, and their values would change with the adding carbon atoms.