title: DFT study of Fe-Ni core-shell nanoparticles: stability, catalytic activity, and interaction with carbon atom for single-walled carbon nanotube growth.
abstract: Metal catalysts play an important role in the nucleation and growth of single-walled carbon nanotubes (SWCNTs). It is essential for probing the nucleation and growth mechanism of SWCNTs to fundamentally understand the properties of the metal catalysts and their interaction with carbon species. In this study, we systematically studied the stability of 13- and 55-atom Fe and Fe-Ni core-shell particles as well as these particles interaction with the carbon atoms using the density functional theory calculations. Icosahedral 13- and 55-atom Fe-Ni core-shell bimetallic particles have higher stability than the corresponding monometallic Fe and Ni particles. Opposite charge transfer (or distribution) in these particles leads to the Fe surface-shell displays a positive charge, while the Ni surface-shell exhibits a negative charge. The opposite charge transfer would induce different chemical activities. Compared with the monometallic Fe and Ni particles, the core-shell bimetallic particles have weaker interaction with C atoms. More importantly, C atoms only prefer staying on the surface of the bimetallic particles. In contrast, C atoms prefer locating into the subsurface of the monometallic particles, which is more likely to form stable metal carbides. The difference of the mono- and bimetallic particles on this issue may result in different nucleation and growth mechanism of SWCNTs. Our findings provide useful insights for the design of bimetallic catalysts and a better understanding nucleation and growth mechanism of SWCNTs.
authors.affiliation: Department of Applied Chemistry, College of Science, Nanjing Tech University, Nanjing 211816, People's Republic of China.
authors.forename: Zhimin
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Department of Applied Chemistry, College of Science, Nanjing Tech University, Nanjing 211816, People's Republic of China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Applied Chemistry, College of Science, Nanjing Tech University, Nanjing 211816, People's Republic of China.
authors.forename: Xiaoye
authors.initials: X
authors.lastname: Shan
authors.affiliation: Department of Physics, Harbin Institute of Technology, Harbin 150001, People's Republic of China.
authors.forename: Wei-qi
authors.initials: WQ
authors.lastname: Li
authors.affiliation: Department of Chemistry, Shantou University, Shantou, Guangdong 515063, People's Republic of China.
authors.forename: Guang-hui
authors.initials: GH
authors.lastname: Chen
authors.affiliation: Department of Applied Chemistry, College of Science, Nanjing Tech University, Nanjing 211816, People's Republic of China.
authors.forename: Hongjun
authors.initials: H
authors.lastname: Zhu