Effective Polarization in Pairwise Potentials at the Graphene–Electrolyte Interface

Abstract

At the graphene-electrolyte interface, the polarizability of both the surface and the solution plays a major role in defining the interfacial structure and dynamics of the ions. Current molecular models predict different ion adsorption behavior at the interface depending on whether surface or solution polarization is included in the model. Here, we propose a simple method to parametrize the ion-carbon interaction from density functional theory, implicitly modeling the solution using the conductor-like polarizable continuum model. The new model simultaneously takes into account the polarizability of both the graphene sheet and the solution without the need to use time-consuming polarizable potentials and can predict the ion adsorption trend so far only achievable using first-principles simulations. Simulations performed with 1 M electrolyte solutions of different ions show that cations are strongly adsorbed onto the graphene surface with a trend (Li < Na < K) opposite to that predicted by the gas-phase calculations and different from that obtained from the single-ion simulations.

Multiscale Simulation of the Interaction and Adsorption of Ions on a Hydrophobic Graphene Surface

“…The obtained interaction energy for Na + in the equilibrium position is in the range from −38 to −39 kcal/mol, which is in good agreement with the previous −38.81 kcal/mol at the ω‐B97X‐D/6‐31+G(d,p) level and −39.60 kcal/mol at the B3LYP/6‐31(G,d) level, respectively. However, our calculated interaction energies were larger than −28.65 kcal/mol calculated by Coiherinhas et al .…”

“…The PMF minimum for Na + adsorption in water is in good agreement with the QM-based interaction energy of hydrated Na + with graphene surface. [13] However, the PMF value is significantly lower than the adsorption energy of Na + in polarizable continuum model, [12] wherein the adsorption energy is only~À3.4 kcal/mol. Com- Figure 4.…”

“…Different efforts have been paid to resolve this issue. Two pioneered studies have been reported by employing the polarizable continuum model and limited number of water molecules to compute the adsorption energy of hydrated ions on graphene surfaces. The calculated results were then applied to optimize the interaction parameters between ion and carbon atoms of graphene.…”

“…The calculated results were then applied to optimize the interaction parameters between ion and carbon atoms of graphene. However, the accuracy and reliability of the polarizable continuum model remain largely suspicious, especially at the aqueous interface. In their result, the computed ion adsorption energy in water is unreasonably lower than the DFT results for hydrated ions with explicit water molecules.…”

2D Laminar Membranes for Selective Water and Ion Transport

“…These heavy metals contain vacant d‐orbits and accept the lone pair electrons donated by the groups, forming strong complexion that immobilizes them inside 2D capillaries . For another thing, the pristine regions favor a cation–π interplay with main‐group ions including alkali (e.g., K + ) and alkaline earth (e.g., Ca 2+ ) cations . The aromatic π‐electron cloud near the sp 2 region exerts a strong attraction force on hydrated cations and pulls them out from the hydration shell to GO surface .…”