Theoretical study on singlet oxygen adsorption onto surface of graphene-like aromatic hydrocarbon molecules

Recently, graphene sheet is one of interesting systems to realize novel electronic properties. Especially, interaction between graphene and adsorbed oxygen molecule is very important to control electronic condition. In this paper, we employed some aromatic hydrocarbons as simple systems of graphene sheet and ab initio MO calculations were carried out to investigate inter-molecular interaction. It is found that not triplet but singlet O2 molecule have potential of chemisorption onto graphene surface. From the calculated potential energy surface (PES) for distance between benzene and O2 molecules, meta-stable structure is found at about 1.5 Å with potential barrier. In the optimized structure of its meta-stable state, structural strain can be relaxed through bending of planer benzene ring. Its energy is estimated at 70.10 kcal/mol for benzene. We also estimated the strain effects for naphthalene and pyrene molecules as larger case of graphene and they were 80.85 and 72.45 kcal/mol, respectively.

We studied electronic properties of three small aromatic hydrocarbon molecules as simplified models for graphene sheets. We assumed their meta-stable states at dioxetane-like structures under adsorption of oxygen molecules and evaluated adsorption energies. The relaxation effects of hydrocarbons with adsorbing O2 were about 70 kcal/mol. This picture is the optimized structure of pyrene–O2 system.Figure optionsDownload as PowerPoint slideHighlights
► Interaction between graphene and adsorbed oxygen molecule is very important to control electronic condition.
► We employed some aromatic hydrocarbons as simple systems of graphene sheet and ab initio MO calculations were carried out to investigate inter-molecular interaction.
► It is found that not triplet but singlet O2 molecule have potential of chemisorption onto graphene surface.
► From the calculated potential energy surface (PES) for distance between benzene and O2 molecules, meta-stable structure is found at about 1.5 Å with potential barrier.
► In the optimized structure of its meta-stable state, structural strain can be relaxed through bending of planer benzene ring.