First-principles Calculation Of Rh-doped And Gas-molecule-adsorbed Rh-doped Nanoribbons

In contemporary, C-substrate graphene nanomaterials greatly promote the development of today's information technology. And in this era of information technology, it is widely used in electronic devices and efficient electronic equipment, among the production is greatly improved efficiency. At the same time, basing on previous theoretical and experimental research:C monolayer atoms compose of graphene (one-dimensional) crystal structure, it is quite high chemical stability and thermal conductivity of caRhon nanotubes (GNTs). The thermal conductivity than the thermal conductivity of diamond is high. In addition, at room temperature, the migration rate of electronic is quite fast. Therefore, the preparation of small power consumption, a new generation of electronic components fast, ready-made material is nanomaterial. The atom doped, gas molecules adsorbed and edge passivation of nanomaterials study:based on the density functional theory (DFT) on the basis of calculation with the first principle, using the projected augmented wave method,firstly, F saturated one-dimensional GaNNRs of the electronic properties and optimize the structure of the model on both sides of the edges; then the gas molecules adsorbed on Rh atom based on the analysis of the different types of graphene substrates, the basic idea is:from the relaxation of the stable structure, density of states, energy band, magnetic and electronic properties of the comparative analysis, and following the draw conclusions:(1) We studied the F and H atoms saturated for different types in GaNNR structure model of bandwidth 6. Firstly, using MS modeling after relaxation, we can get the stability geometric structure model. For comparison with the previous H atoms saturated in GaNNR with different types, we researched the F atoms saturated in GaNNR with different types. By analyzing the optimization model, you can see that the F and H atoms saturated in AGaNNRs edges have obvious change, while no obviously change for the F and H atoms saturated in ZGaNNRs edges. The average bond length of F saturated is bigger than the average bond length of H saturated, since the covalent radius of F atom is bigger than the covalent radius of H atom, which remained internal structure stable among Ga-N. Further analyzing the energy band diagram, F and H atoms saturated in 6-AGaNNRs edges were directly semiconductors, however F and H atoms saturated in 6-ZGaNNRs edge were indirect semiconductors, and F saturated band gap was small than the band gap of H saturated, the reason is that in the area of gamma point, the lowest unoccupied conduction band moving towards the low energy region. We calculated and analyzed the band gap of bandwidth in the range of 2-19, obtaining that the band gap monotonically decreases with the increasing bandwidth. Analyzing the total density of states (TDOS), we can obtain that for F atom saturated in 6-ZGaNNRs and 6-AGaNNRs, the highest valence band is mainly contributed by the N atom, while the lowest conduction band comes from the Ga atom, because N and Ga atoms each have p electrion of three and p electrion of one. The results show that the F atom saturated better than that of H atom for ZGaNNRs edge and AGaNNRs edge due to the smaller band gap of F atom saturated.(2) System of analyzing: different gas molecules adsorption Rh doped graphene substrate by different types of electronic structure and magnetic properties. Due to doping the Rh size was relatively large, making the Rh atom beyond surface of graphene substrate, caused the single vacancy graphene substrate (Rh/SV-graphene) geometric structure obviously change. And the Rh atoms doped in pure graphene substrate (Rh/Pri-graphene) adsorption energy (Eads) larger than the Rh atom doped single vacancy graphene substrate (Rh/SV-graphene) adsorption energy. For substrate doping Rh atoms, transfer more positively electrons to SV-graphene substrate is bigger than the transfer more positively electrons to the Pri-graphene substrate, so changing the characteristics of SV-graphene substrate. Adsorption energy of gas molecules (NO, SO2, CO and H2CO) adsorbed in Rh/Pri-graphene substrate is bigger than adsorption energy in Rh/SV-graphene substrate, due to doping of Rh atoms transferred more electrons from the different substrate to the gas molecules, at the same time, obtaining stable geometry structure. While NO molecular adsorption in Rh/Pri-graphene substrate structure stable than in Rh/SV-graphene substrate structure. The results show that the Rh/Pri-graphene substrate system is semi-metal, while Rh/SV-graphene has the properties of semiconductors.From the point of view the transfer electrons, NO molecules obtained electronic is bigger than CO molecular obtained electronic from the Rh-graphene substrate, so NO molecules adsorbed on Rh/Pri-graphene and Rh/SV-graphene substrates stable than CO molecular adsorption of Rh/Pri-graphene and Rh/SV-graphene substrate. The gas molecules adsorbed on Rh-graphene substrate is stable, causing the electronic structure changes. Compared with the not adsorbed NO molecules density of states, an unbalanced electronic structure appears, the spin down electrons are larger than the spin up electrons. This shows splitting of energy level at the Fermi level. The total density chart of Rh/SV-gra-NO, although at the Fermi level also occurs energy level splitting, however, this makes the spin up electrons larger than the spin down electrons. Compared with the Rh/Pri-graphene, more stable Rh/SV-graphene is more likely to be gas sensor for detecting toxic gases such as NO and SO2. Therefore, each change in the geometric stability, electronic structure and magnetic properties of Rh-graphene substrate materials by the gas adsorption is expected to be an effective materials for the study of gas detection and spintronic device.