利用掺杂提高石墨烯吸附二氧化氮的敏感性及光学性质的理论计算

Theoretical calculation study on enhancing the sensitivity and optical properties of graphene adsorption of nitrogen dioxide via doping

为了研究NO_(2)在未掺杂石墨烯和掺杂石墨烯(N掺杂、Zn掺杂、N-Zn双掺杂)上的吸附,本工作采用密度泛函理论的第一性原理平面波超软赝势对其吸附过程进行模拟.计算了石墨烯表面吸附NO_(2)分子的吸附能、Mulliken分布、差分电荷密度、态密度和光学性质.研究结果表明,与未掺杂石墨烯表面相比,掺杂石墨烯表面对吸附NO_(2)表现出了更高的敏感性,吸附能大小顺序为:N-Zn双掺杂表面>Zn掺杂表面>N掺杂表面>未掺杂表面.未掺杂石墨烯和N掺杂石墨烯表面与NO_(2)的相互作用较弱,是物理吸附.Zn掺杂和N-Zn双掺杂石墨烯表面与NO_(2)之间形成了化学键,是化学吸附.在可见光范围内,3种掺杂方式中N-Zn双掺杂表面对于提高石墨烯光学性能效果最佳,其吸收系数和反射系数的峰值较未掺杂石墨烯表明分别提高了约1.12倍和3.42倍.N-Zn双掺杂石墨烯不但能增强表面与NO_(2)的相互作用,同时也能提高材料的光学性能,这为基于石墨烯基底的NO_(2)气体检测传感提供了理论支撑和实验指导.

In order to study the adsorption of NO_(2)on pristine graphene and doped graphene(N-doped,Zn-doped,and N-Zn co-doped),we simulate the adsorption process by applying the first-principles plane-wave ultrasoft pseudopotentials of the density-functional theory in this work.The adsorption energy,Mulliken distribution,differential charge density,density of states,and optical properties of NO_(2)molecules adsorbed on the graphene surface are calculated.The results show that the doped graphene surface exhibits higher sensitivity to the adsorption of NO_(2)compared with the pristine graphene surface,and the order of adsorption energy is as follows:N-Zn co-doped surface>Zn-doped surface>N-doped surface>pristine surface.Pristine graphene surface and N-doped graphene surface have weak interactions with and physical adsorption of NO_(2).Zn-doped graphene surfac and N-Zn co-doped graphene surface form chemical bonds with NO_(2)and are chemisorbed.In the visible range,among the three doping modes,the N-Zn co-doped surface is the most effective for improving the optical properties of graphene,with the peak absorption and reflection coefficients improved by about 1.12 and 3.42 times,respectively,compared with pristine graphene.The N-Zn co-doped graphene not only enhances the interaction between the surface and NO_(2),but also improves the optical properties of the material,which provides theoretical support and experimental guidance for NO_(2)gas detection and sensing based on graphene substrate.