title: How far away are iron carbide clusters from the bulk?
abstract: Combining the basin hopping structure searching algorithm and density functional theory, the iron carbide clusters, FexCy(x ≤ 8 and y ≤ 8), and clusters with various stoichiometries (Fe2nCn, Fe3nCn, FenC2n, FenC3nand FenC4n(n = 1-7), Fe5nC2n, and Fe4nCn(n = 1-5)) are predicted. The stable structures of iron rich carbide clusters are composed of C-C dimers or single C atoms on the surface of the clusters, which are remarkably different from their corresponding bulk structures, where the carbon atoms are atomically distributed in the iron matrix. The most stable carbon rich clusters are highly diverse in topology (bowl, basket, plane, shoe, necklace, etc.) with long carbon chains. The Bader charge analysis shows that the size effect on iron carbide clusters is an electronic tuning. Large carbon-rich clusters appear even under low carbon chemical potentials, whereas small iron-rich clusters are only energetically stable in high carbon chemical potentials, which indicates that changing the carbon chemical potential can tune the morphology (size and stoichiometry) of the iron carbide clusters. These results may help us understand the catalytic activity of iron and iron carbides in reactions such as the Fischer-Tropsch synthesis and the carbon nanotube formation process.
authors.affiliation: State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, 030001, P. R. China. wxd@sxicc.ac.cn and National Energy Center for Coal to Clean Fuels, Synfuels China Co., Ltd, Huairou District, Beijing, 101400, P. R. China and University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049, P. R. China.
authors.forename: Longyan
authors.initials: L
authors.lastname: Zheng
authors.affiliation: State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, 030001, P. R. China. wxd@sxicc.ac.cn.
authors.forename: Xingchen
authors.initials: X
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, 030001, P. R. China. wxd@sxicc.ac.cn and National Energy Center for Coal to Clean Fuels, Synfuels China Co., Ltd, Huairou District, Beijing, 101400, P. R. China and University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing, 100049, P. R. China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Meng
authors.affiliation: State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, 030001, P. R. China. wxd@sxicc.ac.cn and National Energy Center for Coal to Clean Fuels, Synfuels China Co., Ltd, Huairou District, Beijing, 101400, P. R. China.
authors.forename: Yuwei
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: National Energy Center for Coal to Clean Fuels, Synfuels China Co., Ltd, Huairou District, Beijing, 101400, P. R. China.
authors.forename: Wenping
authors.initials: W
authors.lastname: Guo
authors.affiliation: Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
authors.forename: Qing
authors.identifier: http://orcid.org/0000-0002-8281-8636
authors.initials: Q
authors.lastname: Peng
authors.affiliation: State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, 030001, P. R. China. wxd@sxicc.ac.cn and National Energy Center for Coal to Clean Fuels, Synfuels China Co., Ltd, Huairou District, Beijing, 101400, P. R. China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, 030001, P. R. China. wxd@sxicc.ac.cn and Leibniz-Institut für Katalyse e.V. an der Universität Rostock, Albert-Einstein Strasse 29a, 18059 Rostock, Germany.
authors.forename: Haijun
authors.initials: H
authors.lastname: Jiao
authors.affiliation: State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, 030001, P. R. China. wxd@sxicc.ac.cn and National Energy Center for Coal to Clean Fuels, Synfuels China Co., Ltd, Huairou District, Beijing, 101400, P. R. China.
authors.forename: Yong-Wang
authors.initials: YW
authors.lastname: Li
authors.affiliation: State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, 030001, P. R. China. wxd@sxicc.ac.cn and National Energy Center for Coal to Clean Fuels, Synfuels China Co., Ltd, Huairou District, Beijing, 101400, P. R. China.
authors.forename: Xiao-Dong
authors.initials: XD
authors.lastname: Wen