Fast transport of water in carbon nanotubes: a review of current accomplishments and challenges

Abstract

The intriguing mass transport properties of carbon nanotubes (CNTs) have received widespread attention, especially the rapid transport of water through CNTs due to their atomically smooth wall interiors. Extensive research has been dedicated to the comprehension of various aspects of water flow in contact with CNTs, the most prominent ones being the studies on slip and flow rates. Experimental and computational studies have confirmed an enhanced water flow rate through this graphitic nanoconfinement. However, a quantitative agreement has not yet been attained. These disparities coupled with incomplete knowledge of the mechanisms of water transport at nanoscale regimes are hindering the possibilities to integrate CNTs in numerous nanofluidic applications. In the present review, we focus on the slip and flow rates of water through CNTs and the factors influencing them. We discuss the key sources of discrepancies in water flow rate and suggest directions for future study.

Fast increase of nanofluidic slip in supercooled water: the key role of dynamics

“…For each fluid, when varying the wall type, we already saw a difference at a given temperature in the absolute value of λ, being more than one order of magnitude smaller for graphene than for LJ walls (see the ESI †). This effect has already been measured and discussed in previous work 38,60,89,90 and it is due to the extreme smoothness of graphene. Additionally, in Fig.…”

Highly efficient water desalination through hourglass shaped carbon nanopores

“…2(a) shows the number of water molecules (N w ) crossing the CNT (8,8) nanopores at different half cone angles (α) against time (t). Similar plots for CNT (6,6) and the CNT(10,10) nanopores are given in Fig. S1 of the SI.…”

“…1 shows a representative schematic of the systems used in the study. We used CNTs of chirality (6,6), (8,8) and (10,10) in combination with CNCs of half cone angles (α) 41.8 • , 30.0 • , 19.45 • , 9.6 • -which preserved the hexagonal lattice of the CNCs [42]-to create the nanopores. Graphene sheets of dimensions 88 × 88 Å 2 were placed at the reservoir-nanopore junctions and as pistons.…”

“…Hydrophobic Carbon Nanotubes (CNTs) hold great potential for applications such as desalination, blue-energy harvesting, drug delivery, lab-on-a-chip, and artificial cells owing to their well-defined diameters that can be leveraged for selective transport, and the nearly frictionless water conduction they exhibit [1][2][3][4][5][6]. As a result, studies on transport through CNTs having various dimensions [3,7,8], chemical functionalization [9][10][11], and chirality [12,13] has been conducted, aiming at separation and desalination applications.…”

“…With regard to the aforementioned cause, we have performed molecular dynamics simulations to study desalination through hourglass shaped carbon nanopores by combining CNTs of chirality (6,6), (8,8) and (10,10) and CNCs of half-cone angles (α) 41.8 • , 30.0 • , 19.45 • , 9.6 • , and 0.0 • (α = 0.0 • corresponds to cylindrical CNT). In addition to flow enhancement, we observed an association between the surface curvature and the density structure of water inside the nanopores.…”