Modulation of the electrokinetic streaming potential, as a function of the zeta potential and fluid slip

Modulation of Electrokinetic Potentials Using Graphene-Based Surfaces and Variable Substrate Charge Density

“…The surface charge density (σ s ) on the 2D material surface due to both intrinsic charges as well as electrolyte ion adsorption, in addition to the charge distribution across graphene and the substrate, was considered, as shown in Figure a. On the electrolyte side, the φ­( z ) was obtained through the solution of Poisson’s equation, as derived from the charge density, which in turn requires the solution of the potential dependent Nernst–Planck (N–P) relation. , Consequently, the Poisson and the N–P equations were self-consistently solved in the simulations to determine the overall φ­( z ) in the electrolyte–graphene–substrate system (see Supporting Information for details). The results of the simulation are plotted in Figure b, with the distance from the graphene–electrolyte interface parametrized with respect to a pertinent Debye length (λ D ) and compared with experimental data.…”

“…The ratio of obtained V s in response to a given pressure difference (Δ P ) driving the flow is an appropriate figure of merit (FOM). The magnitude of the V s has been found to be related to both surface chemistry and related charge density. , Further, an improved mechanical-to-electrical energy conversion may be achieved when the surface of the channel is hydrophobic, promoting liquid slip, , which is equivalent to a reduced Δ P . Innovations in surface texture, , and charge engineering of surfaces, e.g., through the design of hydrophobic liquid-filled surfaces (LFS) infiltrated with oil, with possibly larger slip length, have been developed to enhance the V s and the FOM. , …”