jp4123612_si_002.pdf (1.31 MB)
Graphene Nucleation from Amorphous Nickel Carbides: QM/MD Studies on the Role of Subsurface Carbon Density
journal contribution
posted on 2014-05-22, 00:00 authored by Menggai Jiao, Hujun Qian, Alister Page, Kai Li, Ying Wang, Zhijian Wu, Stephan Irle, Keiji MorokumaThe mechanism and kinetics of graphene
formation from amorphous nickel carbides have been investigated employing
quantum chemical molecular dynamics (QM/MD) simulations. Amorphous
Ni3C, Ni2C, and NiC were employed to elucidate
the role of the subsurface carbon density (ρC) on
graphene formation. In each case, the nickel carbide phase underwent
rapid carbon precipitation, resulting in a segregated nickel–carbon
structure. The kinetics of graphene formation was most favorable for
high carbon densities. At low ρC, i.e., Ni3C and Ni2C, there was a tendency for the formation of
a number of small carbon fragments that failed to coalesce due to
their inability to diffuse over the nickel surface. Graphene formation
was only observed in the presence of high carbon densities that were
relatively localized. These simulations, therefore, suggest that graphene
nucleation is not immediately related to the presence of catalyst
carbide phases.