Adsorption of small gas molecules on B36 nanocluster

Borophene as an carrier for mercaptopurine drug: electronic study via density-functional theory computations

CONTEXT

This paper studied MP-B36 interactions through DFT. MP molecules were observed to have a substantial tendency to be adsorbed through their N heads onto B36 at its edge, based on large adsorption energy values. The B atoms at the edges of B36 nanosheets showed higher reactivity than the internal B atoms toward MP. The electronic properties changed upon MP adsorption. The MP-B36 configurations of the highest stability underwent an energy gap reduction of 11-47%. Natural bond orbital (NBO) analysis and molecular electrostatic potential (MEP) analysis were used to evaluate the MP-B36 interaction.

METHODS

The configurations were subjected to geometric optimization at the TPSSH/6-31 + G(d) level of theory, at which frequency analysis was carried out to evaluate the stationary points. These configurations were neutral (Q = 0). The electronic properties of MP dramatically changed upon its interaction with B36 nanosheets. The stable configurations underwent an energy gap reduction, suggesting a chemical signal. The MP molecules were observed to be effectively adsorbed onto the B36 edge within aqueous phases. The MP-B36 configurations were estimated to have relatively large dipole moments. This demonstrated that MP-B36 systems were soluble and dispersed within solar media (e.g., water). It was concluded that B36 nanosheets could serve as efficient MP carriers in nanomedical drug delivery applications.

DFT exploration of adsorptive performances of borophene to small sulfur-containing gases

Density functional theory (DFT) calculations were applied to study the ability of B₃₆ to adsorb H₂S, SO₂, SO₃, CH₃SH, (CH₃)₂S, and C₄H₄S gases. Several exchange-correlation including B97D, PBE, B3LYP, M062X, and WB97XD were utilized to evaluate adsorption energies. The initial results showed that boundary boron atoms are the most appropriate interaction sites. The adsorption energies, electron density, electron localized function, and differential charge density plots confirmed the formation of chemical covalent bonds only between SO_x and B₃₆. The results of thermochemistry analysis revealed the exothermic nature of the adsorption of sulfur-containing gases on B₃₆; the highest values of ∆H₂₉₈ were found for SO₃/B₃₆ and SO₂/B₃₆ systems. The electronic absorption spectra and DOS of B₃₆ did not exhibit significant variations after gases adsorption, while the modeled CD spectra showed a remarkable change in the case of the SO_x/B₃₆ system. Accordingly, B₃₆ is not suggested for detecting the studied gases. The effect of imposing mono vacancy defect and external electric field to the adsorption of titled gases on the sorbent showed, while the former did not affect the adsorption energies significantly the later improved the adsorption of gas molecules on the B₃₆ system. The results of the current study could provide deeper molecular insight on the removal of SO_x gases by B₃₆ system.

Adsorption of toxic gases on borophene: surface deformation links to chemisorptions

β₁₂ borophene has received great attention because of its intriguing mechanical and electronic properties. One of the possible applications of borophene is gas sensing. However, the interaction between common gases and β₁₂ borophene remains to be clarified. In this work, we study the interactions of β₁₂ borophene towards five hazardous gases, namely, CO, NO, NH₃, NO₂, and CO₂ using various non-empirical van der Waals density functionals and provide an insight into the adsorption behavior of borophene. The adsorption mechanism and molecular vibrations are discussed in great detail. Among the gases considered, CO₂ is physisorbed while other gases are chemically bonded to β₁₂ borophene. We also demonstrate that the deformation at the ridge of borophene enables its active p_z orbital to strongly hybridize with frontier orbitals of the studied polar gases. Consequently, borophene is predicted to interact strongly with CO, NO, NH₃, and especially NO₂, making it a sensitive sensing material for toxic gases.

β₁₂ borophene has received great attention because of its intriguing mechanical and electronic properties. One of the possible applications of borophene is gas sensing.

The effect of external electric field and metal impurities on the interaction of HF and boraphene: a computational study

Using density functional theory, the effects of P, Al, and Ga atoms doping on electronic structure of boraphene (B₃₆) were investigated. The results show the highest change in electronic structure of doped-B₃₆ systems belongs to Al-B₃₆ structures wherein the gap energy of the system is decreased by 17.92%. DOS diagrams and absorption spectra of doped B₃₆ are compared to pristine and discussed. The capability of pristine and modified B₃₆ in the field of detection/adsorption of HF molecule has been evaluated. The calculated values of adsorption energies of 0.13, 0.63, 0.24, and 0.16 eV for adsorption of HF on pristine, Al-, Ga-, and P-B₃₆ and related DOS diagrams reveal that these systems are not superior host materials for detection/adsorption applications. It was found that the external electric field could increase the interaction between HF and B₃₆ systems leading to suggesting Al-B₃₆ as proper candidate for HF removal applications.

Quasi-planar B36 boron cluster: a new potential basis for ammonia detection

Detection of NH₃ at a trace level is nowadays of great importance. Here, we investigate the reactivity and sensitivity of a B₃₆ borophene toward NH₃ gas employing DFT calculations. The energetic results point out that the adsorption process strongly depends on the orientation of NH₃ relative to the B₃₆ sheet. An NH₃ molecule preferentially interacts via its N-head with a B atom of the B₃₆ with a change of enthalpy of - 90.5 kJ/mol at room temperature and 1 atm. Mulliken charges analysis results reveal that approximately 0.35 |e| transfers from NH₃ to the B₃₆, leaving partially positive NH₃. We found that the B₃₆ electronic properties are meaningfully sensitive to the NH₃ gas, and it may be a sign of further usage of B₃₆ as a potential NH₃ gas sensor. The density of state analysis shows that the B₃₆ gap is expressively decreased from 1.55 to 1.35 eV, increasing its electrical conductance.

Boron nanostructures obtained via ultrasonic irradiation for high performance chemiresistive methane sensors

We report on a chemiresistive gas sensor using boron nanostructures as the sensing layer, to detect methane gas down to 50 ppm. The sensor showed an excellent response of 43.5-153.1% for a methane concentration of 50 ppm to 105 ppm, with linear behaviour and good response and recovery time. The stability, repeatability, reproducibility, and shelf life of the sensor are promising for next generation methane gas detection.

Structural, electronic, and energetic investigations of acrolein adsorption on B36 borophene nanosheet: a dispersion-corrected DFT insight

The adsorption of acrolein (AC) onto the surface of B₃₆ borophene nanosheet was studied using dispersion-corrected density functional theory (DFT). The structural and electronic properties were scrutinized by several quantum chemical parameters such as HOMO-LUMO gap, condensed Fukui function, molecular electrostatic potential (ESP), and the density of states (DOS). The non-covalent interactions (NCI) were explored by combined reduced density gradient (RDG-NCI) and energy decomposition analysis (EDA) techniques. It was found that the adsorption of acrolein on both convex and concave surfaces of borophene is mainly governed by van der Waals interactions. Our calculations showed that the adsorption energy is strengthened and favored when multiple acrolein molecules adsorb on the edge sides of borophene through their terminal carbonyl oxygen atom. Furthermore, the calculated HOMO-LUMO energy gaps were significantly reduced upon adsorption affecting, therefore, the electrical conductance of borophene. These results should be useful in designing acrolein sensors.

Strong chemisorption of CO2 on B10-B13 planar-type clusters

An ab initio density functional study was performed investigating the adsorption of CO₂ on neutral boron B _n (n  =  10-13) clusters that are characterized by planar and quasiplanar ground-state atomic structures. For all four clusters, we found large chemisorption binding energies, reaching 1.6 eV between CO₂ and B₁₂, with the adsorbed molecule oriented in the plane of the cluster and adsorbed along the cluster edge. A configuration with chemisorbed dissociated CO₂ molecule also exists for B₁₁ and B₁₃ clusters. The strong adsorption is due to the bending of the CO₂ molecule, which provides energetically accessible fully in-plane frontier molecular orbitals matching the edge states of the clusters. At the same time, the intrinsic dipole moment of a bent CO₂ molecule facilitates the transfer of excess electronic charge from the cluster edges to the molecule.

N-H bond cleavage of ammonia on graphene-like B36 borophene: DFT studies

Ammonia N-H bond cleavage at metal-free substrates has attracted great attention because of its industrial importance. Here, we investigate the dissociative adsorption of ammonia onto the surface of a B36 borophene sheet by means of density functional theory calculations. We show that the N-H bond may be broken at the edges of B36 even at room temperature, regarding the small energy barrier of 14.1-19.3 kcal mol(-1) at different levels of theory, and more negative Gibbs free energy change. Unlike basis set size, the kind of exchange correlation functional significantly affects the electronic properties of the studied systems. Also, by increasing the percentage of Hartree Fock (HF) exchange of density functionals, the activation and adsorption energies are lowered. A linear relationship between the highest occupied molecular orbital or lowest unoccupied molecular orbital of B36 borophene and the %HF exchange of functionals is predicted. Our work reveals that pure whole boron nanosheets may be promising metal-free materials in N-H bond cleavage, which would raise the potential application of these sheets.