科研之友
微信
新浪微博
Facebook
分享链接
摘要
The interactions of nitrogen oxides NOx (x = 1,2,3) and N2O4 with graphene and graphene oxides (GOs) were studied by the density functional theory. Optimized geometries, binding energies, and electronic structures of the gas molecule-adsorbed graphene and GO were determined on the basis of first-principles calculations. The adsorption of nitrogen oxides on GO is generally stronger than that on graphene due to the presence of the active defect sites, such as the hydroxyl and carbonyl functional groups and the carbon atom near these groups. These active defect sites increase the binding energies and enhance charge transfers from nitrogen oxides to GO, eventually leading to the chemisorption of gas molecules and the doping character transition from acceptor to donor for NO2 and NO. The interaction of nitrogen oxides with GO with various functional groups can result in the formation of hydrogen bonds OH center dot center dot center dot O (N) between -OH and nitrogen oxides and new weak covalent bonds C center dot center dot center dot N and C center dot center dot center dot O, as well as the H abstraction to form nitrous acid- and nitric acid-like moieties. The spin-polarized density of states reveals a strong hybridization of frontier orbitals of NO2 and NO3 with the electronic states around the Fermi level of GO, and gives rise to the strong acceptor doping by these molecules and remarkable charge transfers from molecules to GO, compared to NO and N2O4 adsorptions on GO. The calculated results show good agreement with experimental observations.
