Adsorption of CO, CO&amp;lt;SUB&amp;gt;2&amp;lt;/SUB&amp;gt;, NO and NO&amp;lt;SUB&amp;gt;2&amp;lt;/SUB&amp;gt; on Carbon Boron Nitride Hetero Junction: DFT Study

M. A. Kamel,H. O. Taha,Kh. M. Eid,A. A. El-Barbary,G. H. Ismail

doi:10.4236/jsemat.2015.54019

Abstract

The adsorption of CO, CO2, NO and CO2 gas molecules on different diameters and chiralities of carbon nanotube-boron nitride nanotube (CNT-BNNT) heterojunctions is investigated, applying the density functional theory and using basis set 6 - 31 g (d,p). The energetic, electronic properties and surface reactivity have been discussed. We found that the best CNT-BNNT heterojunctions for adsorbing the CO, NO, CO2 and NO2 gas molecules is (5,0) CNT-BNNT heterojunction through forming C-N bonds with adsorption energy of -0.26, -0.41 eV, -0.33 and -0.63 eV, respectively. Also, the adsorption of CO, NO, CO2 and NO2 gas molecules on (5,5) and (6,6) CNT-BNNT heterojunctions does not affect the electronic character of the CNT-BNNT heterojunctions, however the adsorption of NO and NO2 gas molecules on (5,0) and (9,0)CNT-BNNT heterojunctions in case of forming C-B bonds increases the band gaps to 1.21 eV and 1.52 eV, respectively. In addition, it is reported that the values of dipole moment for armchair (5,5) and (6,6) CNT-BNNT heterojunctions are not affected by gas adsorption. Also, for the zig-zag (5,0) and (9,0) CNT-BNNT heterojunctions, the values of dipole moment increase through forming C-N bonds and decrease through forming C-B bonds. In addition, it is reported that the highest dipole moment is obtained for (9,0) CNT-BNNT heterojunctions. Therefore, the zig-zag CNT-BNNT heterojunctions can be selected as good candidate for gas sensors.

Highlights

Heterojunction gas sensors have been widely fabricated due to their low cost and simple processing, such as high the triethylamine-sensing of NiO/SnO2 hollowsphere P-N heterojunction sensors [1], the CuO-ZnO heterojunction gas sensors [2] the polypyrrole (Ppy)/TiO2 heterojunction operated LPG sensor [3] the In2O3-WO3 heterojunction nanofibers [4] the SnO2/WO3 heterojunction gas sensor [5] [6] and heterojunctions of B-C-N nanotubes [7]-[9]
It is found that the best carbon nanotubes (CNTs)-boron nitride nanotubes (BNNTs) heterojunction for adsorbing the CO, NO, CO2 and NO2 gas molecules is (5,0) CNT-BNNT through forming C-N bonds with adsorption energy of −0.26 eV, −0.41 eV, −0.33 eV and −0.63 eV, respectively
Our calculated band gaps show that the adsorption of CO, NO, CO2 and NO2 gas molecules on (5,0), (5,5), (6,6) CNT-BNNT heterojunctions does not affect the electronic character of the CNT-BNNT heterojunctions, the adsorption of NO2 gas molecules on (9,0) CNT-BNNT heterojunctions increases the band gap the of (9,0) CNT-BNNTs to ~1.52 eV

Summary

Introduction

Heterojunction gas sensors have been widely fabricated due to their low cost and simple processing, such as high the triethylamine-sensing of NiO/SnO2 hollowsphere P-N heterojunction sensors [1], the CuO-ZnO heterojunction gas sensors [2] the polypyrrole (Ppy)/TiO2 heterojunction operated LPG sensor [3] the In2O3-WO3 heterojunction nanofibers [4] the SnO2/WO3 heterojunction gas sensor [5] [6] and heterojunctions of B-C-N nanotubes [7]-[9]. The single-walled CNTs (SWCNTs) can be metallic or semiconducting, depending on their chirality and diameter. Compared with CNTs, BNNTs are semiconducting with an uniform wide energy gap [14], and their electronic properties are independent of the tube chirality and diameter [15]. The boron nitride nanotubes (BNNTs) do not react with molten metals, and have higher oxidation resistance than CNTs [16] [17]. The adsorption of CO, NO, CO2 and NO2 gas molecules on the surfaces of the heterojunctions with the same diameters and different chiralities for (5,0), (9,0), (5,5) and (6,6) CNT-BNNTs is studied, using the density functional theory and basis set 6 - 31 g (d,p). The electronic properties and surface reactivity of CNT-BNNT heterojunctions have been discussed

Methods

Results

Conclusion