气体吸附对V掺杂石墨烯电子结构与光学性质的影响

基于密度泛函理论(DFT)的广义梯度近似(GGA)，采用第一性原理方法研究了气体分子吸附对V掺杂石墨烯的吸附能、电子结构与光学性质的影响．能带结构计算表明:吸附NO₂分子的V掺杂石墨烯的带隙显著增加，从0 e V变为0.368 e V，由金属性转变为半导体特性，而吸附CO与NH₃分子的V掺杂石墨烯的带隙则变化很小．三种吸附构型(NO₂,CO,NH₃)的吸附能分别为-8.499 e V、-2.05 e V和-2.01e V，说明V掺杂石墨烯对NO₂气体分子吸附最强．进而计算了本征、V掺杂石墨烯及其吸附NO₂分子的光学性质，结果表明:随着V掺杂与吸附NO₂气体，石墨烯介电吸收峰值有所增大，介电峰位向低能量区域移动;本征石墨烯仅吸收紫外光，V掺杂石墨烯吸附NO₂分子可以明显拓宽光吸收的光谱范围;掺杂与吸附使得石墨烯光电导率显著增强，能在红外与可见光区产生光电流．上述结果表明V掺杂石墨烯吸附NO₂后...

Effects of gas adsorption on electronic structure and optical properties of V-doped graphene

Based on the generalized gradient approximation (GGA) under the density functional theory system, the first-principles method was used to investigate the effect of gas molecule adsorption on the adsorption energies, energy band structures and optical properties of the V-doped graphene. The band structure calculation showed that the band gap of V-doped graphene adsorbing NO2 gas molecule is increased from 0eV to 0.368eV, and its material property has also changed from metal to semiconductor. However, the band gaps of V-doped graphene adsorbing CO and NH3 molecules were almost unchanged. The adsorption energies of the three adsorption（NO2,CO,NH3） configurations are -8.499eV, -2.05eV and -2.01eV, respectively, indicating that V-doped graphene has the best adsorption effect on NO2 gas molecules. Furthermore, the optical properties of intrinsic and doped graphene when adsorbing NO2 gas molecules are calculated. The results displayed that the dielectric absorption peak value of graphene is increased with V doping and adsorbing NO2 gas, and the dielectric peak position is moved to the low energy region; Intrinsic graphene can only absorb ultraviolet light, and V-doped graphene can significantly improve the spectral range of light absorption after absorbing NO2 molecule.The photoconductivity of graphene can be significantly enhanced by the doping and adsorption, and the photocurrent can be generated in the infrared and visible light regions. The above research results show that the electronic structures and optical properties of V-doped graphene adsorbing NO2 have been significant changed, and it can be applied as an optical gas sensing material to detect NO2 gas.