Density functional theory analysis for H₂S adsorption on pyridinic N- and oxidized N-doped graphenes

Biomass discharged from primary industries can be converted into methane by fermentation. This methane is used for generating electricity with solid oxide fuel cells (SOFCs). This methane fermentation provides H₂S, which reduces the efficiency of SOFCs even at a level as low as a few parts per million. It has been experimentally reported that a nitrogen (N)-doped graphene-based material known as pyridinic N removes H₂S via an oxidation reaction compared with another graphene-based material known as oxidized N. To understand this experimental result, we investigated H₂S adsorption on pyridinic N and oxidized N by a density functional theory analysis and further examined the activation barrier of dissociation reactions. We found that the adsorption of H₂S on pyridinic N is more stable than that on oxidized N. In addition, the H₂S dissociation reaction occurs only on pyridinic N.