Strong Coupling between Nanofluidic Transport and Interfacial Chemistry: How Defect Reactivity Controls Liquid–Solid Friction through Hydrogen Bonding

Abstract

Defects are inevitably present in nanofluidic systems, yet the role they play in nanofluidic transport remains poorly understood. Here, we report ab initio molecular dynamics (AIMD) simulations of the friction of liquid water on defective graphene and boron nitride sheets. We show that water dissociates at certain defects and that these "reactive" defects lead to much larger friction than the "nonreactive" defects at which water molecules remain intact. Furthermore, we find that friction is extremely sensitive to the chemical structure of reactive defects and to the number of hydrogen bonds they can partake in with the liquid. Finally, we discuss how the insight obtained from AIMD can be used to quantify the influence of defects on friction in nanofluidic devices for water treatment and sustainable energy harvesting. Overall, we provide new insight into the role of interfacial chemistry on nanofluidic transport in real, defective systems.

Tuning dissociation using isoelectronically doped graphene and hexagonal boron nitride: Water and other small molecules

“…Various theoretical studies on band gap engineering using h-BN and graphene mixtures, [15][16][17][18][19][20][21][22][23] have revealed the tuneability of these materials through the mixture of atoms. Other studies have focused on exploiting this tuneability for catalysis of oxygen reduction reactions, [24][25][26][27][28][29][30][31][32][33] water transport, 34 and H 2 adsorption. [35][36][37] An important aspect to consider, if using graphene and h-BN based materials as catalysts, is their degree of selectivity.…”

Full characterization of the hydrodynamic boundary condition at the atomic scale using an oscillating channel: Identification of the viscoelastic interfacial friction and the hydrodynamic boundary position

“…3 illustrate the difficulty to obtain the liquid-solid FC through the evaluation of the Green-Kubo integral of the friction force autocorrelation function [3,45] given by equilibrium MD simulations. In the evaluation of the Green-Kubo integral in systems of finite size, it is often assumed that the mass of the fluid involved in the liquid-solid friction is a finite constant [46][47][48], but the present results show that it is actually frequency dependent.…”

Measuring surface charge: Why experimental characterization and molecular modeling should be coupled

“…In particular, AIMD can be used to compute vibrational spectra and non-linear optical response [147,[160][161][162][163][164], and as such is a key tool to help interpret experimental observations. Recently, liquid-solid friction has been characterized with AIMD [165,166], opening perspectives for the investigation of other transport properties with these methods. At present, however, ab initio methods are typically based on density functional theory, and take electronic exchange and correlations into account through an approximate functional.…”