[en] Highlights: • The most stable structures of Cu_n (n = 10–15) were structures with C_S symmetry. • It is expected that even clusters are better electron donors than the odd clusters. • Acetylene and ethylene adsorb molecularly on the Cu nanoclusters surface. • Acetylene never orient toward di-σ mode for Cu−Cu bond in odd copper nanoclusters. • For di- σ-Cu_nC_2H_4, no stable structure is identified. - Abstract: In this work, we report the results of density functional theory calculations of ethylene and acetylene adsorption on the most stable Cu_n (n = 10–15) nanoclusters, in two π and di- σ adsorption modes. Both the hydrocarbons molecularly adsorbed on the surface. Our results show that the quality of interaction of ethylene and acetylene with odd copper nanoclusters (n = 11, 13, 15) is different from what is found on even copper nanoclusters (n = 10, 12, 14). One of the interesting features of this adsorption is that acetylene never orient toward di-σ mode for Cu−Cu bond in odd copper nanoclusters. Also, for di- σ-Cu_nC_2H_4, no stable structure is identified. The highest interaction and deformation energies are seen for the adsorption of acetylene and ethylene on Cu_1_1 in π-mode.

[en] Graphical abstract: - Highlights: • Solvation energies show that the BNNTs/amino acids complex stabilizes in presence of solvent. • The adsorption process is sensitive to the external electric field. • The electric field is a suitable method for adsorption and storage of amino acids on BNNTs. - Abstract: The interaction of Glu (Glutamic acid), Lys (Lysine), Gly (Glycine) and Ser (Serine) amino acids with different polarities and (9, 0) zigzag single-wall boron nitride nanotubes (BNNTs) with various lengths in the presence and absence of external electric field (EF) in gas and solvent phases, are studied using density functional theory. It is found that interaction of Glu, Lys, Gly and Ser amino acids with BNNTs in both phases is energetically favorable. From solvation energy calculations, it can be seen that the BNNTs/amino acid complex dissolution in water is spontaneous. The adsorption energies and quantum molecular descriptors changed in the presence of external EF. Therefore, the study of BNNTs/amino acid complex under influence of external electric field is very important in proposing or designing new drug delivery systems in the presence of external EF. Results indicate that Glu, Lys, Gly and Ser amino acids can be adsorbed considerably on the BNNTs in the existence of external electric field. Our results showed that the BNNTs can act as a suitable drug delivery vehicle of Glu, Lys, Gly and Ser amino acids within biological systems and strength of adsorption and rate of drug release can be controlled by the external EF

[en] Highlights: • The results suggest that picric acid molecule can be chemisorbed on the surface of the zinc oxide nanotube. • The significant charge transfer could induce significant changes in the electrical conductivity of the tube. • The positive ZnONT might sensitively detect the PA molecule in comparison to the negative tube. - Abstract: Using density functional theory (DFT), we have investigated the adsorption of picric acid (PA) molecule on the surface of (8,0) single-walled ZnO nanotube (ZnONT). The results show that the PA molecule can be chemisorbed on the surface of ZnONT with adsorption energies of −82.01 and −75.26 kJ/mol in gas and aqueous phase, respectively. Frontier molecular orbital analysis show that HOMO/LUMO gap of ZnONT reduces from 1.66 and 1.75 eV in the pristine nanotube to 0.83 and 0.72 eV in PA-adsorbed form in gas and aqueous phase, respectively. It suggests that the process can affect the electronic properties of the studied nanotube which would lead to its conductance change upon the adsorption of PA molecule. The modifying effect on the electrical conductance of ZnONT underlies the working mechanism of gas sensors for detecting the PA molecules. Analyses of the adsorption behavior of the electrically charged ZnONT toward PA molecule in the gas phase show that the PA molecule can be strongly adsorbed on the negatively charged ZnONT surface with significant adsorption energy (−135.1 kJ/mol). However, from the HOMO/LUMO gap changes, it can be concluded that the positive ZnONT might sensitively detect the PA molecule in comparison to the negative tube. These results can provide helpful information for experimental investigation to develop novel nanotube-based sensors

[en] Graphical abstract: - Highlights: • Fe doping on boron nitride nanotubes increases their chemical reactivity. • The vdW interactions have a remarkable contribution of total adsorption energies. • FeNBNNTs is better adsorbent for adsorbing mentioned OPs especially hinosan. • Results can be helpful for planning an efficient nanofilter to remove OP pollutants. - Abstract: In this study, the geometric structures and electronic properties of two widely used organophosphorus pesticides, diazinon and hinosan, boron nitride nanotubes (BNNTs) and Fe doped boron nitride nanotubes (FeBNNTs) as adsorbents of these pesticides are studied by density functional theory calculation as well as dispersion correction by Grimme method. The results show that Fe doping in boron nitride nanotubes structures increases the potency of nanotubes to adsorb mentioned pesticides, especially when Fe atom located instead of N atom. Comparing the adsorption energies of diazinon on FeBNNTs with ones for hinosan demonstrate that the adsorption of hinosan is energetically more favorable by FeBNNTs. Assessment of adsorption energies in aqueous solution confirmed significant decrease in their values compared to ones in gaseous phase. However, the adsorption of diazinon and hinosan on both BNNTs and FeBNNTs are exothermic. So, BNNTs and FeBNNTs may be promising candidates as appropriate adsorbents for adsorbing diazinon and hinosan. Also, the results of calculations have revealed that van der Waals interaction energies are remarkably large in adsorption of diazinon and hinosan on all boron nitride nanotubes.

[en] The electronic and structural properties investigation of pure and zinc, copper, nickel, cobalt doped cadmium oxide nanosheets (CdONS) and the adsorption of ethyl benzene (EB) and ortho- meta- para xylene (OX, MX, PX) on these nanosheets were studied by density functional theory calculations. The adsorption energy, charge transfer, energy gap, spatial distribution of HOMO and LUMO orbitals and electron density scheme of ethyl benzene and ortho, meta, para xylene molecules on pure and doped CdONS are calculated. The obtained results show that the adsorption energy value increases after doping Zn, Cu, Ni and Co atoms in oxygen substituted state, especially in Ni_OCdONS and Co_OCdONS. The adsorption energy of EB, OX, MX and PX on Ni_OCdONS and Co_OCdONS is about − 260 kJ/mol whereas its value on pure CdONS is approximately − 100 kJ/mol. In comparison with pure CdONS, the adsorption energy of the molecules on M_CdCdONS, decreases except in Ni_CdCdONS. The adsorption energy of OX, MX and PX on Ni_CdCdONS is − 263.12, − 150.94 and − 151.85 kJ/mol, respectively. Also, the results show that the value of energy gap increases after the adsorption of EB, OX, MX and PX on Co_OCdONS, therefore, Co_OCdONS can be proposed as proper adsorbent and sensor for these molecules.

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[en] The capability of nickel, cobalt and iron doped graphene nanosheets (GNSs) for adsorption of ozone, sulfur dioxide and nitrogen dioxide molecules are scrutinized by means of density functional theory calculations. The molecular electrostatic potential, adsorption energy and charge transfer of these gas molecules on metal doped GNS are studied. The high negative adsorption energy values exhibit that the nickel, cobalt and iron dopant atoms can remarkably enhance the interaction of molecules with doped GNS. The range of adsorption energy is − 1.45 to − 4.56 eV for the most stable complexes. Also, ozone can be dissociated on Fe doped GNS. The results indicated that the iron doped GNS is the most effective for adsorbing ozone, nitrogen dioxide and sulfur dioxide molecules. After adsorption of these molecules, the energy gaps of the doped GNSs are decreased in all complexes. This investigation shows that doped GNSs based nanomaterials can be helpful for controlling and capturing of harmful gases.

[en] Highlights: • Dissociative adsorption of hydrogen was determined on the Cu₁₁ nanocluster. • E_ad of C₂H₂ on Cu₁₁2H complex is higher than the E_ad of C₂H₄. • Cu₁₁ nanocluster can be used as catalyst for the selective hydrogenation of C₂H₂. In this paper, by the density functional theory (DFT) calculations we show that the copper nanocluster can be used as catalyst for the hydrogenation of acetylene and ethylene. Since the nature of dissociation of hydrogen molecule on the copper nanocluster is the governing step for the hydrogenation reaction, the adsorption and complete dissociation of H₂ on the Cu₁₁ nanocluster is investigated at PBE-G/DNP-ECP level of theory. The results show that H₂ is adsorbed dissociatively on the Cu₁₁ nanocluster. To examine the activity of copper nanocluster as a catalyst for the hydrogenation reaction, the hydrogenations of acetylene and ethylene are investigated on the free Cu₁₁ nanocluster, due to its highest adsorption energies for hydrogen, acetylene and ethylene adsorptions. In the presence of the Cu₁₁ nanocluster as a catalyst, acetylene and ethylene can be hydrogenated to ethylene and ethane, respectively. These reactions are exothermic with the total reaction energies of −247.61 and −174.01 kJ/mol for hydrogenation of acetylene and ethylene, respectively. One of the interesting features of this catalyst is that the energy of acetylene adsorption on Cu₁₁2H complex is higher than the energy of ethylene adsorption. It seems that Cu₁₁ nanocluster can be used as catalyst for the selective hydrogenation of acetylene. Also, we choose graphene as a support for copper nanocluster and the hydrogenation of acetylene and ethylene on graphene-supported Cu₁₁ nanocluster are investigated. Based on our DFT calculations, we suggest graphene-supported Cu₁₁ nanoclusters as candidates with good activity and selectivity for the acetylene hydrogenation reaction.

[en] Adsorption of ozone and carbon monoxide molecule on the surface of two stable isomers of C₆₀O fullerene oxide has been calculated using the density functional theory method. A systematic evaluation showed that the open [5,6] isomer reacts with the O₃ molecule by adsorption energy of −168.71kJ/mol and significantly charge transfer from fullerene oxide to ozone molecule. Furthermore, O₃ molecule adsorption has a considerable effect on the energy gap of open [5,6] fullerene oxide which is indicated the high sensitivity of electronic features of this isomer of C₆₀O toward O₃ adsorption. From the results, it was found that closed [6,6] isomer of fullerene oxide adsorbs the CO molecule with significant adsorption energy compared to the [5,6] isomer. Based on the findings, we propose that the C₆₀O stable isomers are remarkable materials for future experimental studies for adsorption and removal of ozone and carbon monoxide molecules.

[en] Highlights: • Spin-dependent electronic transport properties on single ferrocene molecule. • Highly effect of anchoring atoms on the control of spin transport properties. • Observation of high spin-filtering and negative differential resistance behaviors. Spin transport properties of a single ferrocene molecule connected between gold electrodes by amine (NH₂), sulfur (S) and titanium (Ti) linkers are investigated using density functional theory through a non-equilibrium Green’s function approach. The results clearly reveal that the anchoring groups can significantly modify the spin-dependent properties due to shift of the frontier orbitals. This will give rise to some interesting phenomena including robust spin-filtering effect and obvious negative differential resistance behavior. Importantly, the linkers dramatically influence the bias region of spin-filtering diagram. The numerical results suggest that such single molecular junctions would be efficiently implemented for developing spintronic devices.