Effect of electric field on water free energy in graphene nanochannel

Graphene nanochannels and nanostructures have been of great interest to applications like nanofluidics and solar-thermal evaporation since nanoconfinement can lead to altered liquid properties. In this article, we employ molecular dynamics simulations combined with the free energy perturbation method to study the influence of external electric fields on the free energy of water molecules in graphene nanochannels. We observe a decrease in the water free energy difference (delta G(1-0) = G(0 )- G(1), where 0 is the reference vacuum state and 1 is the solvated state) with the increasing electric field, suggesting that the application of an electric field may reduce the thermal energy needed to evaporate water from graphene nanochannels. Our analysis reveals that the reduction in free energy difference is related to more aligned water molecules along the electric field direction in the nanochannels, which leads to a decrease in the water inter-molecular potential energy and, thus, reduces the free energy difference. Published under an exclusive license by AIP Publishing.

Automated summary

In this study, the influence of external electric fields on the free energy of water molecules in graphene nanochannels was investigated using molecular dynamics simulations and the free energy perturbation method. It was found that the application of an electric field can reduce the thermal energy required to evaporate water from the nanochannels, which is related to the alignment of water molecules in the channels.