HF and SiF4 adsorption on carbon graphite (1 1 1) surface in aqueous medium: A combined DFT and MD simulation approach

Abstract

In this study, the adsorption properties of silicon tetrafluoride (SiF4) and hydrogen fluoride (HF) were investigated using density functional theory (DFT) and molecular dynamics (MD) simulation approaches. Many quantum chemical parameters related to the adsorption mechanism and global reactivity were calculated such as ELUMO, EHOMO, energy gap (ΔEgap), softness (S), chemical hardness (η), electronegativity (χ), chemical potential (µ), electrophilicity (ω), nucleophilicity (N), electrons transferred from molecules to graphite surface (ΔN), initial molecule-graphite interaction energy (Einteraction) and the energy change during the electronic back-donation process (ΔEb-d). The adsorption behaviors of the studied molecules on graphite (1 1 1) surface were investigated with the help of the molecular dynamics simulation. The optimum geometric configurations of the adsorption of SiF4 and HF on different possible sites in the graphite surface have been established. The corresponding adsorption energies, bond distances, Mulliken charges and electron density difference plots have been analyzed to understand the interaction at each site. The binding energies calculated for SiF4 were greater than those calculated for HF. The dynamic descriptors obtained were in good agreement with the results of quantum parameters.