▎ 摘　　要

Water and ion transport through graphene nanochannels has attracted considerable attention thanks to the possibility of dimensional control of the channel sizes down to a single atomic layer. Using molecular dynamics simulations, we systematically analyzed the coupled transport of water and ions in the solutions of LiCI, NaCI, and KCI salts as a function of channel sizes, applied electric fields, and salt concentrations. A universal order of ion flux is found with K1(+) > Cl- > Na+approximate to Li+ and the K+ flux is twice as large as those of Na+ and Li+ indicating the ion selectivity with such graphene channels. The local structures and transport dynamics within the channels show sensitive dependence on the channel height, forming two-dimensional hydration shells in the low-height limit. The hydration shells of the ions undergo transformation from three- to two-dimensional structures upon entering the narrow channel. A power law relationship between the ion translocation time and electric field is also found and can be well described by the one-dimensional Langevin equation. In addition, the linear relation between the ion flux and concentration agrees well with the one-dimensional Poisson-Nernst-Planck equation. Our results provide insights into the ionic transport through graphene channels and have implications for the design of novel nanofluidic devices for selective ion transport in future applications.