Silver oxide cluster cations (AgnOm+) can readily be produced by a number of methods including atmospheric-pressure spark ablation of pure silver electrodes when trace amounts of oxygen are present in the carrier gas. Here we determine the equilibrium geometries of AgnOm+ clusters (n = 1-4; m = 1-5) using accurate coupled cluster with singles and doubles (CCSD) method, while the stabilization energies are calculated with additional perturbative triples correction (CCSD(T)). Although a number of stable states have been identified, our results show that the AgnOm+ clusters with m = 1 are more stable than those with m ≥ 2 due to the absence of the terminally attached O2 molecule, corroborating recent observations by mass spectrometry. Using the computed structures, we calculate the electrical mobilities of the AgnOm+ clusters and label the values on a respective experimentally determined spectrum in an attempt to better interpret the occurrence of the peaks and troughs in the measurements.

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.

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, ωB97XD, 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 investigated here, SiCGeNT shows the most favourable for designing effective HCFC-124 nanosensors.

In this paper, we have theoretically determined the possibility of adsorption of the gaseous CH₂N₂ molecule on the surface of X₁₂Y₁₂ nanocages, where X = B, Al, Ga and Y = N, P, As. The electronic structure calculations have been performed by density functional theory (DFT) using four functionals (i.e., B3LYP-D3, M06-2X, ωB97XD, and CAM-B3LYP), together with the 6-311G(d) basis function. We find that the adsorption of CH₂N₂ on top of the X–Y bond of the nanocage is the most preferred site for adsorption. The adsorption process is accompanied by a charge-transfer phenomenon, which results in a strong bond between the terminal N atom of diazomethane and the X atom of the nanocage. This gives rise to significant changes in the highest and lowest occupied molecular orbital (HOMO and LUMO, respectively) energies and thus attribute properties to the nanocages that enable themto act as building blocks of CH₂N₂ sensing materials.

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.