Molecular insights from theoretical calculations explain the differences in affinity and diffusion of airborne contaminants on surfaces of hBN and graphene

• Published in: Applied surface science Vol. 565; p. 150382
• Main Authors: Otyepková, Eva, Skladanová, Katarína, Pykal, Martin, Blahová Prudilová, Barbora, Kašlík, Josef, Čépe, Klára, Banáš, Pavel, Lazar, Petr, Otyepka, Michal
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2021
• Subjects: Adsorption; Density functional theory; Graphene; Hexagonal boron nitride; Inverse gas chromatography; Inverse gas chromatography; Density functional theory; Hexagonal boron nitride; Adsorption; Graphene
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2021.150382

[Display omitted] •molecular adsorption on hBN was characterized by inverse gas chromatography.•edge adsorption causes peculiar coverage dependency of adsorption enthalpy.•theoretical calculations were essential for interpreting experimental results. Exposed surfaces of two-dimensional (2D) materials are susceptible to the adsorption of various molecules including airborne contaminants, which can affect their performance in real applications. Hexagonal boron nitride (hBN) is structurally the closest relative to graphite and its single layer form to graphene. The adsorption of organic molecules to graphene was subject of extensive research, however, little is known about interaction ofadsorbates to hBN surface. We studied the affinity of organic molecules to the surface of hBN by inverse gas chromatography. The adsorption enthalpies of polar molecules including acetonitrile, nitromethane, ethanol, and acetone exhibited strong coverage dependency up to 20 % of a monolayer. Density functional theory and molecular dynamics calculations were employed to understand and interpret experimentally measured adsorption enthalpies. The calculations revealed that the strong affinity of polar molecules at low coverage was due to adsorption on steps and edges of hBN. The calculated surface diffusion barriers of all molecules were rather low, i.e., below 0.5 kcal/mol (except for benzene and cyclohexane), and molecules adsorbed on the surface behaved like a 2D gas. The results demonstrated that coupling inverse gas chromatography with computer simulations can provide vital insights into the mechanism of adsorption at the molecular level.