Graphdiyne nanotubes in ionic liquids: Characterization of interfacial interactions by molecular dynamics

Abstract

The interfacial interaction between ionic liquids and γ-graphdiyne nanotubes (GDYNT) has been scarcely explored, however, due to the porosity of the latter, it may be of interest to the development of improved energy storage devices. Here, the interfacial interactions in mixtures of [Emim][TFSI] and [Hmim][TFSI] with GDYNT are uncovered and compared to the interactions in mixtures of those ionic liquids with carbon nanotubes (CNTs). The porosity of GDYNT, in addition to its less stiff sidewall, allows an increased proximity between ions and the carbon sidewall, when compared to CNTs. It was demonstrated that hydrogen atoms (from cations) and fluorine atoms (from anions) assume preferential positions near the center of GDYNT’s pores, and, while [Emim] cations permit an almost crystal like packing of the ionic liquid inside GDYNT, the large alkyl “tail” of [Hmim] cation impedes that layer ordering. It was also found that the porous nature of GDYNT acts partially as a very fine sieve, “gluing” smaller atoms to its surface, while removing the remainders, which was not observed in mixtures of ionic liquids with CNTs. A detailed characterization of the interfacial interactions between ionic liquids and GDYNTs, using molecular dynamics modeling, is here presented for the first time.