Search

The sensitivity of terpyrrole (TPy; used as a polypyrrole model) to toxic hydrogen cyanide (HCN) adsorption was studied by using DFT to perform geometry optimization and to calculate the adsorption energy of HCN on TPy as well as orbital properties. The interaction of terpyrrole with HCN was studied for different relative orientations of the molecules. The adsorption energy, charge analysis, and the density of states were used to evaluate the ability of TPy to sense HCN in these different relative orientations. The adsorption energy was calculated to be −3.9 and −3.1 kcal mol−1 for two possible relative orientations. Frontier molecular orbitals and energies indicated that some hybridization occurs during the adsorption of HCN on TPy when the molecules have appropriate relative orientations, resulting in an increase in conductivity. Considering the changes in the HOMO-LUMO energy gap that were calculated to occur during HCN adsorption, it is clear that TPy is sensitive to HCN adsorption, suggesting that TPy has the potential to act as an HCN sensor. [ABSTRACT FROM AUTHOR]

First-principles analysis based on density functional theory was performed to compute the electronic and transport properties of a single-walled carbon nanotube in the presence of hydrogen cyanide. A chiral (4,1) carbon nanotube was found to become less metallic as the number of hydrogen cyanide molecules nearby increased. When there were a sufficient number of hydrogen cyanide molecules close to the nanotube, it became semiconducting. This metallic to semiconducting transformation of the nanotube was verified by analyzing its conductance and current as a function of the number of molecules of hydrogen cyanide present. The conductivity of the carbon nanotube was very high when no hydrogen cyanide molecules were present, but decreased considerably when even just a single hydrogen cyanide molecule approached the surface of the nanotube. [ABSTRACT FROM AUTHOR]

The interactions between HCN and reduced graphene oxides (rGO) are investigated using first-principles calculations with M06-2X functional. The results show that the adsorption of HCN on rGO is generally stronger than that on graphene, which is due to the presence of the active defect sites in rGO, such as the hydroxyl, epoxide, and carboxyl functional groups and even the carbon atom near these groups. The interaction between HCN and rGO with oxygen-containing group can result in the formation of hydrogen bonds, N · · · H and O · · · H. The adsorption of HCN on rGO depends on the type and location of oxygen-containing group in rGO. Carboxyl group on rGO is much more attractive for HCN than hydroxyl and epoxide group. The adsorption of HCN is much stronger in rGO with oxygen-containing group on the surface than that at the edge. The adsorption of HCN on rGO with carboxyl attached to vacancy on the surface is the strongest. [ABSTRACT FROM AUTHOR]

Hydrogen cyanide (HCN) adsorption on pristine and B–N doped biphenylene nanosheets was investigated by means of density functional theory calculations. According to biphenylene geometry, all distinct possible B–N substitutions were designed. Adsorption energy and electronic structure at the level of M062X/6-31 g (d,p) theory were computed for all possible geometries. Our results reveal that pristine biphenylene nanosheet is not a suitable candidate for HCN detection. Also, for B–N doping, the sensitivity of the nanosheet depends on the B–N doped configuration. One of these derivative structures shows higher sensitivity to HCN adsorption due to the greater change in electronic properties. Moreover, atoms in molecules and natural bond orbital analysis were performed to obtain more in-depth knowledge about the adsorption mechanism. The range of energy for interaction between HCN and the nanosheets belongs to physical adsorption. [ABSTRACT FROM AUTHOR]

The present paper reports the analysis of surface decoration on the structural, electronic, and optical properties of (n,0) ZnO nanotubes, performed by means of a density function theory based ab-initio approach. Fe functionalization induced buckling in ZnO nanotubes affects its electronic and optical properties. Increase in Fe functionalization leads to better stability of ZnO nanotube and shows enhanced metallic character. The possibility of its use in optoelectronics has been analyzed in terms of dielectric constant, absorption coefficient, and refractive index. In another observation, the high sensitivity of the HCN molecule for the Fe-incorporated ZnO nanotube suggests it as a potential gas sensor.HCN-adsorbed Fe-ZnO nanotube, electron difference density, and PDOS analysis of different orbitals. [ABSTRACT FROM AUTHOR]

The sensitivity of terpyrrole (TPy; used as a polypyrrole model) to toxic hydrogen cyanide (HCN) adsorption was studied by using DFT to perform geometry optimization and to calculate the adsorption energy of HCN on TPy as well as orbital properties. The interaction of terpyrrole with HCN was studied for different relative orientations of the molecules. The adsorption energy, charge analysis, and the density of states were used to evaluate the ability of TPy to sense HCN in these different relative orientations. The adsorption energy was calculated to be -3.9 and -3.1 kcal mol(-1) for two possible relative orientations. Frontier molecular orbitals and energies indicated that some hybridization occurs during the adsorption of HCN on TPy when the molecules have appropriate relative orientations, resulting in an increase in conductivity. Considering the changes in the HOMO-LUMO energy gap that were calculated to occur during HCN adsorption, it is clear that TPy is sensitive to HCN adsorption, suggesting that TPy has the potential to act as an HCN sensor. Graphical abstract HCN adsorption on TPy.