Molecular dynamics study of electro-osmotic flow in a nanochannel with molybdenum disulfide walls

Abstract

The electro-osmotic flow (EOF) in a neutral system consisting of an aqueous NaCl solution confined in a nanochannel with two parallel Molybdenum disulfide (\(\text {MoS}_{\text {2}}\)) walls and in the presence of an external electric field parallel to the channel walls, is investigated for the first time. The results indicate that the thickness of the Stern layer grows as the negative electric surface charge density on the nanochannel walls increases. The Stern layer becomes thinner as the salt concentration is increased. Moreover, the EOF occurs under the no-slip condition on the walls. In addition, by increasing the surface charge density the average of the flow velocity across the nanochannel initially grows (Debye–Hückel regime) and reaches its maximum value. Then, by further increasing the surface charge density the water flow rate decreases (intermediate regime), and gets the zero value and becomes negative (reverse flow regime) at even larger values of the surface charge densities. Comparing the results of the previous work wherein the channels are composed of the black phosphorene walls with those of the present study for a channel composed of \(\text {MoS}_{\text {2}}\) surfaces, show that for the latter case the reverse flow occurs at a lower surface charge density and with a greater value of the peak velocity with respect to the change in the surface charge density for the former case.