Kinetic Study of Few Layer Graphene Growth on Cu-Ni Alloy Catalyst: A Density Functional Theory Approach

The tunable electronic and optical properties of few layer graphene (FLG) make it potential for transparent conductive electrode applications. The FLG with precisely controlled number of layers can be grown using Chemical Vapor Deposition (CVD) method on the Cu-Ni alloy catalyst. However, the effect of Ni atom concentration in the Cu-Ni alloy catalyst on the FLG growth mechanism is still not fully understood. The kinetic aspect studies still need to be conducted to get a comprehensive picture of the growth process. Therefore, in this study, we use the density functional theory method to study the effect of Ni atom concentration on the growth mechanism of graphene on Cu-Ni alloy catalyst from the kinetic aspect. We consider two catalyst models, namely Cu-Ni-1 (6.25 at % Ni) and Cu-Ni-3 (18.75 at % Ni) catalysts and two kinetic processes, namely diffusion of C atoms over the catalyst surface and diffusion of C atoms from the surface to the subsurface of the catalyst. We found that increasing the concentration of Ni atoms causes a reduction in the activation energy of the diffusion of C atoms from the surface to the subsurface of the catalyst, which in the case of Cu-Ni-2 catalyst is 0.16 eV. This activation energy is lower than the single atom energy at the graphene growth temperature (0.17 eV). This result indicates that Cu-Ni catalysts with Ni atom concentrations greater than 18.75% can be used to grow FLG with precisely controlled number of layers. This finding can be used as a guidance for experimental research in order to grow few layer graphene with high quality. Keywords: density functional theory, electronic conductivity, few-layer graphene, transmittance