Application of carbon nanostructures toward SO₂ and SO₃ adsorption: a comparison between pristine graphene and N-doped graphene by DFT calculations

We studied the adsorption of SOx (x = 2,3) molecules on the surface of pristine graphene (PG) and N-doped graphene (NDG) by density functional theory (DFT) calculations at the B3LYP/6-31G(d) level. We used Mulliken and NBO charge analysis to calculate the net charge transfer of adsorbed SOx on pristine and defected graphene systems. Our calculations reveal much higher adsorption energy and higher net charge transfer by using NDG instead of pristine graphene. Furthermore, the density of state (DOS) graphs point to major orbital hybridization between the SOx and NDG, while there is no evidence of hybridization by using pristine graphene. Based on our results, it is found that SO2 and SO3 molecules can be adsorbed on the surface of NDG physically and chemically with adsorption energies (Eads) of −27.5 and 65.2 kJ mol−1 (19.6 and 51.4 kJ mol−1 BSSE), respectively, while low adsorption energies were calculated in the case of using pristine graphene. So we introduced NDG as a sensitive adsorbent/sensor for detection of SO2 and SO3.

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