The interaction of ammonia with the protic ionic liquid ethylammonium nitrate: A simulation study

Abstract

In this paper, we present a molecular dynamics study of ammonia solutions in a protic ionic liquid with a structurally similar cation, ethylammonium nitrate. Using two different models of the ammonia molecule, a conventional 4-site model and a 6-site model optimizing the dipolar and quadrupolar electron distributions, we evaluate their effect on the microstructure and single-particle dynamics of these mixtures, as well as on their behaviour at the electrochemical interface. Quite significant differences are found on the solvation of ammonia in these dense ionic solvents, the 6-atom model predicting a stronger affinity of solvent molecules for the cations of the solvent as well as a caging effect on NH3 solvation shells, not predicted by the 4-site model. Finally, we discuss the structure of the liquid layers near charged graphene walls. The structure in the layer next to the wall varies with the charge on the wall and varies with the model used for ammonia.