| 摘要: | 本篇使用了密度泛函理論搭配不同的基底函數與計算軟體分別模擬計算了螺旋型奈米碳管與含金屬缺陷石墨烯系統，前者做結構與電子性質的分析；後者是以此系統針對常見溫室氣體做不同位向的氣體吸附，做為後續氣體偵測器之研究參考。
螺旋型奈米碳管(n, m)的部分由邊界週期條件的模型下，計算出無限長度下(6, m)至(20, m)系列的螺旋型奈米碳管，其中(6, m)至(9, m)系列有一完整系列的結構與電子性質分析。從結果觀測到螺旋型奈米碳管會有三種不同鍵長分布，當隨著碳管管徑增加的時候，平均鍵長會逐漸縮短至符合共振鍵性質的長度，而所有鍵長分布的差異亦會漸漸縮小；另外電子性質的部分皆是符合緊束理論n-m=3N的規則。 金屬缺陷石墨烯系統對常見氣體與溫室氣體(O2、O3、SO2、SO3、H2S、CO、CO2、N2O、CH4)做不同位向的氣體吸附。實驗結果發現此系統均吸附雙原子氣體，其中O2最佳，而三原子氣體中吸附O3、SO2為佳，多原子氣體以SO3為佳，所有氣體中唯有CH4是無吸附的現象。此外藉由電子性質的改變可以做為未來使用偵測氣體的依據，外接一電子裝置偵測其被吸附後的氣體Eg值改變量，作為判斷氣體有無吸附也是一個未來可行的方法。
Optimized structures and related electronic properties for zigzag, armchair, and chiral single-walled carbon nanotubes were obtained and discussed by using periodic boundary condition-density functional theory (PBC-PBE) method. The whole series from (6, m) to (9, m) and the other selected series of carbon nanotubes were calculated, and we found the different bond length distribution existed in our designed system. When the chiral angle and tubular diameter increased, not only the average bond length would decrease to have the double bond character but also the difference of the bond length distribution would decrease. The electronic properties of all calculated chiral SWCNTs were followed the “n-m=3N” rule under the tight binding theory. The N-doped defective graphene with Fe2+ ion (4N-HDG-Fe) was designed and expected to play a role in gas sensor. In this study, the different absorption orientation for the normal and the greenhouse gases (O2、O3、SO2、SO3、H2S、CO、CO2、N2O、CH4) at the design 4N-HDG-Fe system were investigated. The optimized structures, binding energies (Eb), and electronic properties (EHOMO, ELUMO, and Eg) were obtained by using the DFT-PBE/DZP and DFT-B3LYP/LANL2DZ method. Calculated results shows that the relative lower Eb for O2, O3, SO2, and SO3 can be found among these absorbed gases. Thus, it is the suitable choice to capture above gases by using 4N-HDG-Fe which based on the Eb consideration. The Eg of 4N-HDG-Fe would be changed by the absorbed gases in our study. This property may provide an useful information for further application of gas senser. |
