H2S adsorption on graphene in the presence of sulfur: A density functional theory study

Abstract The high affinity of graphene for H 2 S makes it a potential adsorbent for separating H 2 S from industrial waste gas streams, and for its use in H 2 S sensors. The gas streams containing H 2 S also contain S atoms that can get bonded to graphene during adsorption. Moreover, at high temperatures, H 2 S dissociate at graphene defects leading to H 2 desorption with S atom remaining on graphene. This study reports the effect of the presence of S atom on graphene on H 2 S adsorption using plane-wave density functional theory to assess the suitability of graphene-based adsorbents for continuous H 2 S capture. During H 2 S interaction with pristine graphene with S atom bonded to it, a surface cleaning mechanism was observed, where H 2 S exothermically removed S atom by forming H 2 S 2 . When S atom was doped in the single-vacancy defect of graphene, both physisorption and chemisorption of H 2 S was observed. The adsorption energy released during H 2 S physisorption on S-doped graphene was comparable to that for pristine graphene. However, during chemisorption, H 2 S dissociated on S-doped graphene to form HSSH bonded to graphene with the release of a high amount of energy. The results suggest that S atom in single-vacancy defects can enhance H 2 S capture on graphene.