Gated Water Transport through Graphene Nanochannels: From Ionic Coulomb Blockade to Electroosmotic Pump

Understanding and controlling water or ion transport in nanochannels plays an important role in further unravelling the transport mechanism of biological membrane channels and designing functional nanofluidic devices. Molecular dynamics simulations were conducted to investigate water and ion transport in graphene nanochannels. Similar to electron coulomb blockade phenomenon observed in quantum dots, we discovered an ionic coulomb blockade phenomenon in our graphene nanochannels, and another two ion transport modes were also proposed to rationalize the observed phenomena under different electric-field intensities. Furthermore, on the basis of this blockade phenomenon we found that the Open and Closed states of the graphene nanochannels for water transport could be switched according to external electric-field intensities, and electroosmotic flow could further enhance the water transport. These findings might have potential applications in designing and fabricating controllable valves in lab-on-chip nanodevices

Molecular Dynamics Simulations of CO₂/N₂ Separation through Two-Dimensional Graphene Oxide Membranes

Graphene oxide (GO), as an ultrathin, high-flux, and energy-efficient separation membrane, has shown great potential for CO₂ capture. In this study, using molecular dynamics simulations, the separation of CO₂ and N₂ through the interlayer gallery of GO membranes was studied. The preferential adsorption of CO₂ in the GO channel derived from their strong interaction is responsible for the selectivity of CO₂ over N₂. Furthermore, the influences of interlayer spacing, oxidization degree, and channel length on the separation of CO₂/N₂ were investigated. Our studies unveil the underlying mechanism of CO₂/N₂ separation in the interlayer GO channel, and the results may be helpful in guiding rational design of GO membranes for gas separation