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In this paper, the microscopic mechanism and optical properties of nitric oxide (NO) molecules adsorbed on the surface of graphene were studied theoretically by using the first principles of plane wave ultra-soft pseudopotential calculation method based on density functional theory. In order to obtain more accurate results, the effects of dispersion interaction, long-range electron correlation effect and Van der Waals force are taken into account. The exchange correlation functional of DFT-D and generalized step approximation of PBE is used to optimize the geometric structure. The plane wave ultra-soft pseudopotential method is used to describe the interaction between electron and ion. The Kohn-Sham equation and the energy functional are solved by self-consistent method. According to the three adsorption sites on the surface of graphene - top site, bridge site and vacancy site, the adsorption model of NO molecules on the surface of 14 kinds of graphene was constructed. The adsorption energy, Mulliken distribution, differential charge density, state density and optical properties of NO molecules adsorbed on graphene surface were calculated. The results show that NO molecules are easily adsorbed on the surface of single-O doped, single-N doped and O-N double-doped graphene by chemical adsorption. All three kinds of doping will form a new impurity level near the Fermi level of graphene, which will help the electronic transition and improve the optical properties of graphene. In the range of visible light 360-780 nm, the optical properties of NO molecules adsorbed by C-N bond bridge site on the surface of O-N double-doped graphene are the best, and the peak absorption coefficient and reflection coefficient of O-N double-doped graphene are increased by about 1.40 times and 1.84 times, respectively, compared with that of undoped graphene. This work deepens the understanding of the process of NO molecule adsorption on graphene surface and its microscopic mechanism, and provides theoretical support for the study of NO sensing based on graphene materials. [ABSTRACT FROM AUTHOR]

Tn recent years, graphene/polyurethane nanocomposites have attracted much attention due to their superior comprehensive properties. Incorporating graphene or its derivatives into I〉U matrix could significantly improve the physical mechanical, thermal, electromagnetic and other properties, which meets the special requirements of high-performance and multi-functional polymer composites. Tn this paper, the functional modification methods of graphene nanosheets, including covalent modification and non-covalent modification were first introduced. Furthermore, the fabrication processes of graphene/poly urethane nanocomposites, including in-situ polymerization, solution blending, melt blending, aqueous (latex) blending, etc., were briefly introduced. The recent research progress of graphene/poly urethane composites in mechanical, electrical, dielectric, thermal, gas barrier, flame retardant, electromagnetic interference shielding and corrosion resistant properties were all reviewed in detail. The future challenges and development prospects of high-performance graphene/poly urethane nanocomposites were also prospected. [ABSTRACT FROM AUTHOR]