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.

Automated summary

Burning hydrocarbons as fuel, a major contributor to global warming, can introduce hydrocarbons into the environment through their use as fuels and chemicals or through accidents. This study used density functional theory (DFT) to investigate the adsorption behavior of C2H4, CH4, and H2 on nitrogen and sulfur-doped graphene quantum dot surfaces. Theoretical calculations showed stable and favorable gas adsorption on the doped surfaces. The calculated adsorption energies, as well as parameters from quantum theory of atoms in molecules (QTAIM) and natural bond orbitals (NBO), confirmed the stability and intermolecular interactions of the surfaces. GQD_N and GQD_S were found to be good adsorbents for C2H4, CH4, and H2 gases, respectively.