The utilization of an external electric field (EF) for improving the chemical reactions on low-dimensional systems has been of growing interest in recent years. In this work, we investigated the effect of an external electric field on the adsorption and the C-H bond activation of methane on iron-embedded graphene (Fe-GPs) by using the M06-L density functional method. The EF is applied in the perpendicular to the graphene in the range of -0.02 � +0.02 au with an interval of 0.005 au. It is found that it affects the adsorption, transition state and product complexes of the methane activation reaction. The methane adsorption on the Fe site in Fe-GPs is increased from 10.8 to 13.1, 15.8 and -19.1 kcal/mol for the negative EF of -0.005, -0.010 and -0.015 au, respectively. With applying the positive EF, the activation barriers for methane activation are dramatically reduced in the range of 3-10 kcal/mol (around 15-40%) due mainly to its inducing the transition state to appear early in the reaction coordinate. The reaction energies of the reaction also become less endothermic with this positive EF. This shows that the positive EF makes the reaction more kinetic and thermodynamic compared to the system without EF. From these findings, it can therefore be suggested that the adsorption and activation of methane on Fe-GPs can be easily tuned by using the appropriate electric field. This might be a promising strategy for applications of metals embedded on GPs to capture and also to activate the methane C-H bond.

Effect of external electric field on methane activation over Fe-embedded graphene: DFT study

248th National Meeting (2014)

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