Ion transport in sub-5-nm graphene nanopores

Abstract

Graphene nanopore is a promising device for single molecule sensing, including DNA bases, as its single atom thickness provides high spatial resolution. To attain high sensitivity, the size of the molecule should be comparable to the pore diameter. However, when the pore diameter approaches the size of the molecule, ion properties and dynamics may deviate from the bulk values and continuum analysis may not be accurate. In this paper, we investigate the static and dynamic properties of ions with and without an external voltage drop in sub-5-nm graphene nanopores using molecular dynamics simulations. Ion concentration in graphene nanopores sharply drops from the bulk concentration when the pore radius is smaller than 0.9 nm. Ion mobility in the pore is also smaller than bulk ion mobility due to the layered liquid structure in the pore-axial direction. Our results show that a continuum analysis can be appropriate when the pore radius is larger than 0.9 nm if pore conductivity is properly defined. Since many applications of graphene nanopores, such as DNA and protein sensing, involve ion transport, the results presented here will be useful not only in understanding the behavior of ion transport but also in designing bio-molecular sensors.

Geometrical Effect in 2D Nanopores

“…A small discrepancy is observed if using the modified models, which explains the lack of the knowledge of the overestimated ion conductivity inside the pore. 45 Compared to the small α pore value in h-BN, ions have much higher permeability through MoS 2 nanopores, that is clearly visible for the MoS 2 points fitted with α pore = 0.8 which is close to the bulk value. In other words, the channel resistance plays a major role in sensing molecules in the case of h-BN nanopores; however, it results in a smaller total conductance drop.…”

Nanoporous graphene as a reverse osmosis membrane: Recent insights from theory and simulation

“…The water transport across NPG does not proceed strictly in a single file. Instead, water molecules rapidly diffuse away from the nanopore after passing through the membrane, meaning that entrance/exit effects dominate the transport behavior, unlike in CNTs [78]. The angular orientation of water permeating through graphene also exhibits a distinct ordering effect [79].…”

Elastic and structural properties and buckling behavior of single-walled carbon nanotubes under chemical adsorption of atomic oxygen and hydroxyl

“…After many intense investigations on the intrinsic properties of pure CNTs, numerous researchers concentrated on developing the effective ways to control the properties of CNTs to apply them in certain applications and nanodevices. Functionalization is found to be a practical and efficient way to tailor the properties of nanostructures in order to use them in the wide range of applications in biotechnology and drug delivery nanodevices [3][4][5][6][7][8][9][10][11][12]. Functionalization can be performed through different methods such as doping or introducing any defects on CNTs, exohedral and endohedral polymer functionalization [13][14][15][16][17] and atomic-decoration [18][19][20][21][22][23][24][25][26][27].…”