Investigation of the influence of the location of oxygenated functional groups in graphene nanostructures on water permeation via molecular dynamics simulations

Remarkable Thermal Performance Enhancement of Micro Heat Pipes with Graphene-Nanoplatelet Nano-Wicks

“…From 12 s onwards, the water molecules intercalate frictionlessly into nanochannels formed by the graphene layers (each individual graphene nanoplatelet consists of a few graphene layers functionalized with oxygenated groups), as depicted in the inset of Figure 1 . This leads to the ultrafast water permeation phenomenon where the fluorescence intensity flux decreases rapidly as shown in Figure 3 d. The oxygenated functional groups such as hydroxyl, epoxy, carbonyl and carboxyl groups play their critical role in propelling the water molecules through the graphene nanochannels [ 44 , 45 , 46 , 47 ]. The smooth hydrophobic carbon-walled layers allow near-frictionless flow of water molecules, and the oxygenated functional groups engender driving force for fast water permeation across the hydrophobic carbon walls.…”

“…The ultrafast water permeation of GNPs is attributed to the frictionless interaction between the water molecules and the carbon wall as well as the hydrophilic attraction force of oxygenated functional groups. Molecular dynamics simulations have been conducted to elucidate the ultrafast water permeation mechanism of GNPs [ 44 , 46 , 48 ]. Through the nanocapillary pressure induced by the GNP nano-wicks, the water molecules are expediated from the condenser section to the evaporator section.…”

“…The ultrafast water permeation property of graphene-based materials has been extensively utilized in various applications, such as desalination [ 36 , 37 , 38 , 39 ], nanofiltration [ 40 , 41 , 42 , 43 ] and phase-change heat transfer [ 9 , 15 , 29 ] systems. Among the carbon nanomaterials, the GNPs are found to exhibit the most superior ultrafast water permeation property [ 44 , 45 , 46 ]. GNPs consist of multilayers of exfoliated graphene nanosheets with the oxygenated functional groups—such as hydroxyl, epoxy, carbonyl, carboxyl groups—attached at their periphery [ 6 , 44 , 45 , 46 ].…”

“…Among the carbon nanomaterials, the GNPs are found to exhibit the most superior ultrafast water permeation property [ 44 , 45 , 46 ]. GNPs consist of multilayers of exfoliated graphene nanosheets with the oxygenated functional groups—such as hydroxyl, epoxy, carbonyl, carboxyl groups—attached at their periphery [ 6 , 44 , 45 , 46 ]. The hydrophilic oxygenated functional groups act as the driving-force source of the ultrafast water permeation property, which generates the intercalation of water molecules through the carbon nanostructures.…”

“…The hydrophilic oxygenated functional groups act as the driving-force source of the ultrafast water permeation property, which generates the intercalation of water molecules through the carbon nanostructures. In the non-oxidized regions, vacant spaces formed between graphene nanosheets and the ultrafast water permeation is attributed to the near-frictionless interaction between the hydrophobic carbon wall and the well-ordered hydrogen bonds of water molecules [ 46 , 47 ]. Therefore, the atomic-scale capillaries and cavities allow ultrafast water transport induced by the high capillary pressures, and large slip lengths are formed in the GNP nanostructures.…”