Enhancing the absorption of 1-chloro-1,2,2,2-tetrafluoroethane on carbon nanotubes: an ab initio study

We have investigated the possibility of utilizing various single-walled pristine and doped carbon nanotubes as adsorbents for the 1-chloro-1,2,2,2-tetrafluoroethane (HCFC-124) gaseous molecule. Three candidates, including pristine carbon nanotube (CNT), silicon carbide nanotube (SiCNT) and germanium-doped SiCNT (SiCGeNT) are identified and evaluated theoretically. The quantum simulations have been performed at the density functional theory (DFT) level with four different functionals (i.e., M06-2X, xB97XD, CAM-B3LYP and B3LYP-D3) with a split-valence triple-zeta basis set (6-311G(d)). We found that adsorption on the SiCGeNT is most favourable, while that on the pristine CNT yields the lowest adsorption energy. Adsorption on these nanotubes is not accompanied by an active charge-transfer phenomenon; instead, it is driven by weak van der Waals forces. The HOMO–LUMO energy gaps drastically change when the dopant atom is added to the SiCNT, thereby improving their overall adsorption capability. Among all of the adsorbents inves�tigated here, SiCGeNT shows the most favourable for designing effective HCFC-124 nanosensor

Theoretical investigation of X₁₂O₁₂ (X = Be, Mg, and Ca) in sensing CH₂N₂: A DFT study

The feasibility of detecting diazomethane (CH2N2) in the gas phase by adsorption onto the exterior surface of inorganic-based X12O12 (where X can be Be, Mg, or Ca) nanocages is investigated here using DFT. All the structures, including those of the pristine CH2N2 and of the nanocages, as well as of the CH2N2/nanocage systems, have been optimized using the B3LYP-D3, M06-2X, ωB97XD, and CAM-B3LYP functionals, in conjunction with 6-311G(d) basis set. NBO, NCI, and QTAIM analyses results are in good agreement with each other. Furthermore, the Density Of States (DOSs), the natural charges, the Wiberg Bond Indices (WBI), and natural electron configurations were considered to investigate the nature of intermolecular interactions. The energy calculations indicate a strong size-dependent adsorption, with the nanocages comprised of large atoms being able to attract CH2N2 more strongly, and hence bind with it more effectively. The adsorption incurs also significant changes to HOMO and LUMO energies.Accepted Author ManuscriptAtmospheric Remote Sensin

Silicon Carbide Based Nanotubes as a Sensing Material for Gaseous H₂SiCl₂

The ability of carbon- and silicon-based nanotubes, including pure carbon, silicon carbide, and Ge-doped silicon carbide nanotubes (CNT, SiCNT, SiCGeNT, respectively), for sensing highly toxic dichlorosilane (H2SiCl2) are investigated using quantum chemistry calculations. The intermolecular interactions between the sensing material and the gas molecule have been investigated with the density functional theory calculations with a functional that includes dispersion terms. The selected method employed is B3LYP-D3 (GD3BJ)/6-311G(d), while other functionals including PBE0, ωB97XD, and M06-2X have been used for comparison. The quantum theory of atoms in molecules (QTAIM) analysis is employed to check the type of intermolecular interactions. Natural bond orbital (NBO) calculations have been used to deduce the bond orders. The findings of this work indicate that the adsorption of the H2SiCl2 is a physisorption process, which is very desirable for its function as a sensing element. The Ge-doped nanotube offers maximum adsorption energy in comparison to CNT and SiCNT.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Atmospheric Remote Sensin

Adsorbing CNCl on pristine, C-, and Al-doped boron nitride nanotubes: A density functional theory study

The density functional theory (DFT) framework was used to investigate the intermolecular interactions between cyanogen chloride (CNCl) pollutant gas molecule with pristine boron nitride nanotubes (BNNT), Al-doped boron nitride nanotubes (BNAlNT), and carbon boron nitride nanotubes (BC2NNT). The geometric structures of the resulting systems have been optimized using different methods, including B3LYP-D3(GD3BJ)/6-311G(d), ωB97XD/6-311G(d), and M06-2X/6-311G(d). The computed adsorption energies suggest that the studied nanotubes can enhance adsorption of CNCl, and thus promote its detection when employed as sensing materials. Wave function analysis has been implemented to study the type of intermolecular interactions at ωB97XD/6-311G(d,p) level of theory. Natural bond orbital (NBO) analysis has been used to study the charge transfer and bond order. Quantum theory of atoms in molecules (QTAIM) analysis has also been used to determine the type of interactions between the target gas and the nanotubes. To investigate the weak intermolecular interactions we also carried out non-covalent interaction analysis (NCI). The results also indicate that the CNCl-nanotube systems are created through physisorption as they are dominated by non-covalent interactions. The predicted adsorption energies increase as follows: BNAlNT: −1.175 eV > BC2NNT: −0.281 eV > BNNT: −0.256 eV; this shows that the aluminum-doped boron nitride nanotube is the best option from promoting adsorption of the target gas among them. The HOMO–LUMO energy gaps were as follows: BNNT: 7.090, BNAlNT: 9.193, and BC2NNT: 7.027 eV at B3LYP-D3/6-311G(d) level of theory.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Atmospheric Remote Sensin

Effect of Al- And Ga-doping on the adsorption of H₂SiCl₂ onto the outer surface of boron nitride nanotube: A DFT study

There is a compelling reason to design cost-effective sensors to detect and measure harmful molecules such as dichlorosilane (H2SiCl2) in the air. In this work, density functional theory (DFT) has been used to study the nature of the intermolecular interactions between the H2SiCl2 gas molecule with a single-walled pristine, Al-doped, and Ga-doped boron nitride nanotubes (BNNT, BNAlNT, and BNGaNT, respectively) to investigate their potential in gas-sensing applications. Full-dimensional geometry optimization and adsorption energies were calculated with four functionals: PBE0, M06-2X, ωB97XD, and B3LYP-D3 with a 6-311G(d) basis set. We find that the B, Al, or Ga atoms provide the most favorable sites for adsorption of the H2SiCl2 molecule. The adsorbate is more tightly bound to the surface of the doped rather than of the pristine BNNT nanotubes, demonstrating a larger energy gain due to adsorption. This is due to the fact that H2SiCl2 interacts with pristine BNNT through weak Van der Waals forces but seemingly has stronger ionic interactions with the doped variants. In general, introducing impurities can improve the selectivity and reactivity of the BNNT toward H2SiCl2. Among all of the absorbents, we find that BNGaNT exhibits the highest affinity toward H2SiCl2, and therefore holds a higher potential compared to the rest of the nanotubes investigated here for designing materials for dichlorosilane sensors.Atmospheric Remote Sensin

On the bending of MS1-P20 hybrid steels additively manufactured using laser powder bed fusion

Maraging steel (MS1)-tool steel (P20) bimetals additively manufactured using the laser powder bed fusion technique were studied under different heat treatment cycles and loading conditions. The hardening of P20 and aging of MS1 were performed sequentially on the hybrid samples. The interfacial characteristics and microstructural evolution of the bulk materials were studied using various advanced electron microscopy techniques. The post-processing procedures successfully produced a uniform martensitic structure throughout the MS1-P20 hybrid steels, leading to a less detectable interface under electron backscatter diffraction (EBSD) imaging. The mechanical performance of heat-treated hybrid steels was evaluated using complex loading conditions. 3-point and 4-point bending tests were performed to assess the impact of heat treatments on the mechanical performance of the hybrid steels. The heat-treated samples exhibited higher strength with relatively homogeneous hardness variations and deformed more uniformly in bending conditions.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Team Jilt Sietsm

Adsorption of air pollutants onto silver and gold atomic clusters: DFT and PNO-LCCSD-F12 calculations

We provide a comprehensive investigation of intermolecular interactions between atmospheric gaseous pollutants, including CH4, CO, CO2, NO, NO2, SO2, as well as H2O and Agn (n = 1-22) or Aun (n = 1-20) atomic clusters. The optimized geometries of all the systems investigated in our study were determined using density functional theory (DFT) with M06-2X functional and SDD basis set. The PNO-LCCSD-F12/SDD method was used for more accurate single-point energy calculations. Compared to their isolated states, the structures of the Agn and Aun clusters undergo severe deformations upon adsorption of the gaseous species, which become more significant as the size of the clusters decreases. Considering that, in addition to adsorption energy, we have determined the interaction and deformation energy of all the systems. All our calculations consistently show that among the gaseous species examined, SO2 and NO2 exhibit a higher preference for adsorption on both types of clusters, with a slightly higher preference for the Ag clusters compared to the Au clusters, with the SO2/Ag16 system exhibiting the lowest adsorption energy. The type of intermolecular interactions was investigated through wave function analyses, including natural bond orbital (NBO) and quantum theory of atoms in molecules (QTAIM), showing that NO2 and SO2 are chemisorbed on the Agn and Aun atomic clusters, whereas the other gas molecules exhibit a much weaker interaction with them. The reported data can be used as input parameters for molecular dynamics simulations to study the selectivity of atomic clusters towards specific gases under ambient conditions, as well as to design materials that take advantage of the studied intermolecular interactions.Atmospheric Remote Sensin

Electronic properties and collision cross sections of AgOkHm± (k, m = 1–4) aerosol ionic clusters

Experimental evidence shows that hydroxylated metal ions are often produced during cluster synthesis by atmospheric pressure spark ablation. In this work, we predict the ground state equilibrium structures of AgOkHm± clusters (k and m = 1–4), which are readily produced when spark ablating Ag, using the coupled cluster with singles and doubles (CCSD) method. The stabilization energy of these clusters is calculated with respect to the dissociation channel having the lowest energy, by accounting perturbative triples corrections to the CCSD method. The interatomic interactions in each of the systems have been investigated using the frontier molecular orbital (FMO), natural bond orbital (NBO) and quantum theory of atoms in molecules (QTAIM) methods. Many of the ground states of these ionic clusters are found to be stable, corroborating experimental observations. We find that clusters having singlet spin states are more stable in terms of dissociation than the clusters that have doublet or triplet spin states. Our calculations also indicate a strong affinity of the ionic and neutral Ag atom towards water and hydroxyl radicals or ions. Many 3-center, 4-electron (3c/4e) hyperbonds giving rise to more than one resonance structure are identified primarily for the anionic clusters. The QTAIM analysis shows that the O–H and O–Ag bonds in the clusters of both polarities are respectively covalent and ionic. The FMO analysis indicates that the anionic clusters are more reactive than the cationic ones. Using the cluster structures predicted by the CCSD method, we calculate the collision cross sections of the AgOkHm± family, with k and m ranging from 1 to 4, by the trajectory method. In turn, we predict the electrical mobilities of these clusters when suspended in helium at atmospheric pressure and compare them with experimental measurements.ChemE/Materials for Energy Conversion and StorageAtmospheric Remote Sensin

Lowest electronic states of neutral and ionic LiN

We have investigated the potential energy curves (PECs) of the LiN heteronuclear diatomic molecule, including its ionic species LiN+ and LiN−, using explicitly correlated multi-reference configuration interaction (MRCI-F12) calculations in conjunction with the correlation consistent quintuple- basis set. The effect of core–valence correlation, scalar relativistic effects, and the size of the basis sets has been investigated. A comprehensive set of spectroscopic constants determined based on the above-mentioned calculations are also reported for the lowest electronic states and all systems, including dissociation energies, harmonic and anharmonic vibrational frequencies, and rotational constants. Additional parameters, such as the dipole moments, equilibrium spin-orbit constants, excitation energies, and rovibrational energy levels, are also documented. We found that the three triplet states of LiN, namely, X 3∑−, A 3Π, and 2 3∑−, exhibit substantial potential wells in the PEC diagrams, while the quintet states are repulsive in nature. The ground state of the anion also shows a deep potential well in the vicinity of its equilibrium geometry. In contrast, the ground and excited states of the cation are very loosely bound. Charge transfer properties of each of these states are also analyzed to obtain an in-depth understanding of the interatomic interactions. We found that the core–valence correlation has a substantial effect on the calculated spectroscopic constants.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Atmospheric Remote Sensin

Gas-Phase Interaction of CO, CO₂, H₂S, NH₃, NO, NO₂, and SO₂ with Zn₁₂O₁₂ and Zn₂₄ Atomic Clusters

Atmospheric pollutants pose a high risk to human health, and therefore it is necessary to capture and preferably remove them from ambient air. In this work, we investigate the intermolecular interaction between the pollutants such as CO, CO2, H2S, NH3, NO, NO2, and SO2 gases with the Zn24 and Zn12O12 atomic clusters, using the density functional theory (DFT) at the meta-hybrid functional TPSSh and LANl2Dz basis set. The adsorption energy of these gas molecules on the outer surfaces of both types of clusters has been calculated and found to have a negative value, indicating a strong molecular-cluster interaction. The largest adsorption energy has been observed between SO2 and the Zn24 cluster. In general, the Zn24 cluster appears to be more effective for adsorbing SO2, NO2, and NO than Zn12O12, whereas the latter is preferable for the adsorption of CO, CO2, H2S, and NH3. Frontier molecular orbital (FMO) analysis showed that Zn24 exhibits higher stability upon adsorption of NH3, NO, NO2, and SO2, with the adsorption energy falling within the chemisorption range. The Zn12O12 cluster shows a characteristic decrease in band gap upon adsorption of CO, H2S, NO, and NO2, suggesting an increase in electrical conductivity. Natural bond orbital (NBO) analysis also suggests the presence of strong intermolecular interactions between atomic clusters and the gases. This interaction was recognized to be strong and noncovalent, as determined by noncovalent interaction (NCI) and quantum theory of atoms in molecules (QTAIM) analyses. Overall, our results suggest that both Zn24 and Zn12O12 clusters are good candidate species for promoting adsorption and, thus, can be employed in different materials and/or systems for enhancing interaction with CO, H2S, NO, or NO2Atmospheric Remote Sensin