Adsorption and gas-sensing investigation of oil dissolved gases onto nitrogen and sulfur doped graphene quantum dots

Burning hydrocarbons as fuel, which produces carbon dioxide and water, is a major contributor to anthropogenic global warming. Hydrocarbons are introduced into the environment through their extensive use as fuels and chemicals as well as through leaks or accidental spills during exploration, production, refining, or transport of fossil fuels. Herein, theoretical calculations based on density functional theory (DFT) was applied to investigate the adsorption behavior of C₂H₄, CH₄ and H₂ on graphene quantum dot surfaces doped with Nitrogen (N) and sulfur (S) (GQD_N, GQD_S). Theoretical calculations in this study were obtained with the dispersion correction in consideration so as to predict intermolecular interactions alongside B3LYP-D3(BJ)/6-311+G (d, p). The sites that were doped with N and S atom were found to be more stable and suitable for gas adsorption. The adsorption energy was computed to establish the surface abilities of the adsorptions under investigation. Gas adsorptions on surfaces showed similar high negative values. We may deduce from the computed adsorption energies that GQD_N and GQD_S have strong adsorptions and considered adsorptions are thermodynamically favored. The ellipticity parameter calculated using the quantum theory of atoms in molecules (QTAIM), as well as the stabilization energies obtained from natural bond orbitals (NBO), confirmed the stability of surfaces upon gas adsorptions. QTAIM also confirmed remarkable intermolecular interactions. This result also agrees with that for non-covalent interactions, which predicted weak intermolecular interactions between surface and gas molecules. GQD_N and GQD_S are good adsorbents that can adsorb C₂H₄, CH₄, and H₂ gases, respectively.