共查询到20条相似文献,搜索用时 109 毫秒
1.
This study provides details of the electronic and optical structures and binding energies of sarin (SF) and chlorosarin (SC) with Al–N and Al–P surfaces of Al 12N 12 and Al 12P 12 nanoclusters in the gas phase. The adsorption mechanism of SF and SC on these nanoclusters containing the Al 3+ central cation was studied. Optimized geometries and thermodynamic parameters of SF and SC adsorption complexes were calculated. SF and SC are chemisorbed on these nanoclusters because of the formation of PO···Al bonds. The chemical bond is formed between an oxygen atom of SF and SC and an aluminum atom of fullerene-likes (chemisorption). However, the binding energies of the complexes with the Al 12N 12 nanocluster are larger than these values for the Al 12P 12 nanocluster. The interaction enthalpy and Gibbs free energy of all studied systems were found to be negative. We can conclude that SF and SC will be adsorbed preferably on Al 12N 12 nanocluster. 相似文献
2.
The nature of intermolecular interactions between BN nanocones (BNNCs) and temozolomide (TMZ) drug has been described by using Wiberg bond index (WBI) and natural bond orbital (NBO) analyses. The adsorption energy of TMZ on the Si and Ge-decorated BNNCs were calculated to be about ??17.64 and ??16.47 kcal mol?1, respectively. Also, after TMZ adsorption, the band gap energy (Eg) value of Si (Ge)-decorated BNNCs has reduced significantly by about 51.41% (50.99%), increasing the electrical conductivity, while the Eg value of pristine BNNCs was slightly reduced after TMZ adsorption. It indicates that the Si (Ge)-decorated BNNCs compared to pristine state could be more appropriate candidate for TMZ detection and may be used in the electronic sensors. Furthermore, the work function of Si (Ge)-decorated BNNCs is influenced by the TMZ adsorption, and the work function of decorated and pristine BNNCs is reduced by about 32.42% and 4.15%, respectively. The nature of interactions between TMZ and BNNCs is noncovalent based on the WBI and NBO results. 相似文献
3.
Abstract Density functional theory (DFT) calculations at the B3LYP/6–31G* level were performed to investigate covalent functionalization of imidazole on pristine (in gas and H 2O phases) and Ga-doped BPNT models in terms of energetic, geometric, and electronic properties. The results show that imidazole, as a functional group, prefers to be adsorbed via its nitrogen atom on the pristine, Ga B, and Ga P nanotube models. The adsorption energy of imidazole on the (6,0) zigzag BPNT in gas and solvent phases is ?0.76 and ?1.11 eV, respectively, and about 0.38 and 0.43 electron are transferred from the imidazole to nanotube in the phases. The presence of a polar solvent increases the electron donor of imidazole molecule. The results show that Ga doping can significantly enhance the adsorption energy of imidazole on the nanotube models to about 95%. Moreover, the imidazole adsorption on the pristine and Ga-doped BPNT models has not significant changes in the energy gap of the nanotube models and it is slightly changed after covalent functionalization process. This study may provide new insight to the development of functionalized boron phosphide nanotubes for generation of the new hybrid compounds especially in drug delivery systems for virtual applications. 相似文献
4.
The weak photoluminescence of silver nanoclusters prevents their broad application as luminescent nanomaterials. Recent experiments, however, have shown that gold doping can significantly enhance the photoluminescence intensity of Ag 29 nanoclusters but the molecular and physical origins of this effect remain unknown. Therefore, we have computationally explored the geometric and electronic structures of Ag 29 and gold‐doped Ag 29?xAu x ( x=1–5) nanoclusters in the S 0 and S 1 states. We found that 1) relativistic effects that are mainly due to the Au atoms play an important role in enhancing the fluorescence intensity, especially for highly doped Ag 26Au 3, Ag 25Au 4, and Ag 24Au 5, and that 2) heteronuclear Au?Ag bonds can increase the stability and regulate the fluorescence intensity of isomers of these gold‐doped nanoclusters. These novel findings could help design doped silver nanoclusters with excellent luminescence properties. 相似文献
5.
Small Ag n nanoclusters ( n<10) have been emerging as promising materials as sensing, biolabeling, and catalysis because of their unique electronic states and optical properties. However, studying synthesis, structure determination, and exploration of their properties remain major challenges as a result of the low stability of small Ag nanoclusters. Herein, we synthesized an atomically precise face-centered-cubic-type small {Ag 7} 5+ nanocluster supported by a novel triangular hollow polyoxometalate (POM) framework [Si 3W 27O 96] 18−. The cluster showed unique {Ag 7} 5+-to-POM charge transfer bands in both visible and UV light regions. Furthermore, this small {Ag 7} 5+ nanocluster exhibited an unprecedented ultrastability in solution, despite having exposed Ag sites that can be accessed by small molecules, such as O 2, water, and solvents. 相似文献
6.
The H 2 physisorption on Ag N (with N = 32, 108, 256, 500, and 864)/carbon nanotube (CNT; in armchair and zigzag structures with diameters between 0.54 and 2.98 nm) composites were studied by molecular dynamic simulation to investigate the effect of nanocluster size, diameter, and chirality of nanotube on the adsorption phenomena. The calculations indicate that the effects of nanocluster properties are more important than those of the nanotube, in such a way that increase of nanocluster size, decreases the H 2 adsorption. Also, the diameter and chirality of CNTs have considerable influence on the adsorption phenomena. As the diameter of nanotube is increased, the amount of adsorption is decreased. Moreover, H 2 molecules have more tendencies to those nanoclusters located on the armchair nanotubes than the zigzag ones. Another important result is the reversibility of H 2 adsorption on these materials in which the structure of composite in vacuum and after reduction of H 2 pressure to zero, is not changed, considerably. © 2015 Wiley Periodicals, Inc. 相似文献
7.
Density Functional Theory employing hybrid and M06 functionals in combination with three different basis sets is used to calculate the ground state of a cage like (ZnO) 12 nanocluster which has been consistently reported as the more stable cluster for its particular size. B3LYP and B3PW91 hybrid functionals combined with 6‐31+G*, Lanl2dz and SDD basis sets are employed to treat the ZnO molecular system. Alternatively, three M06 functionals in combination with three basis sets are employed in the nanostructure calculations. Results obtained by treating ZnO sodalite cage nanocluster with M06 functionals demonstrated comparable quality to results obtained with hybrid functionals. Within this study, efficient theoretical DFT methods with the widely known hybrid and the recently created M06 meta‐hybrid functionals are employed to study nanostructured ZnO. Our resulting parameters provide a fresh approach performance wise on the different theoretical methods to treat transition metal nanostructures, particularly, ZnO nanoclusters geometry and electronic structure. 相似文献
8.
Small Ag n nanoclusters ( n<10) have been emerging as promising materials as sensing, biolabeling, and catalysis because of their unique electronic states and optical properties. However, studying synthesis, structure determination, and exploration of their properties remain major challenges as a result of the low stability of small Ag nanoclusters. Herein, we synthesized an atomically precise face‐centered‐cubic‐type small {Ag 7} 5+ nanocluster supported by a novel triangular hollow polyoxometalate (POM) framework [Si 3W 27O 96] 18?. The cluster showed unique {Ag 7} 5+‐to‐POM charge transfer bands in both visible and UV light regions. Furthermore, this small {Ag 7} 5+ nanocluster exhibited an unprecedented ultrastability in solution, despite having exposed Ag sites that can be accessed by small molecules, such as O 2, water, and solvents. 相似文献
9.
We have performed MD simulations to investigate H 2 adsorption on Ag–Au nanoclusters with the different Au mole fractions supported on the carbon nanotubes with the different diameters. Our thermodynamic results shown that the saturation value of coverage and the enthalpy of adsorption increases as the mole fraction of Au is increased. Our structural results showed that the presence of the H 2 gas exerts a significant effect on the nanocluster surface atoms and tends to stabilize the surface atoms on the nanocluster. Also, the structural changes are irreversible in such a way that by gradually decreasing the pressure to zero, the nanocluster geometry is not reversed to its initial structure in vacuum conditions. We have also shown that the nanoclusters have smaller values of the self‐diffusion coefficients in presence of H 2 molecules than those values in the initial state (vacuum), which is due to the increasing of the interface structure between the nanocluster and the nanotube. 相似文献
10.
Adsorption of N2O molecule by using density functional theory calculations at the B3LYP/6–31G* level onto pristine and Si‐doped B12N12 nanocage in terms of energetic, geometric, and electronic properties was investigated. The results of calculations showed that the N2O molecule is physically adsorbed on the pristine and Si‐doped B12N12 (SiN) models, releasing energies in the range of –1.13 to –2.02 kcal mol−1. It was found that the electronic properties of the models have not changed significantly upon the N2O adsorption. On the other hand, the adsorption energy of N2O on the Si‐doped B12N12 (SiB model) was about –67.20 kcal mol−1and the natural bond orbital charge of 0.58|e| is transferred from the nanocage to the N2O molecule. In the configuration, the O atom of N2O molecule is bonded to the Si atom of the nanocage, so that an N2 molecule escapes from the wall of the nanocage. The results showed that the SiB model can be an adsorbent for dissociation of the N2O molecule. 相似文献
11.
A novel Au 11Cd nanocluster was synthesized by developing a combined method and controlling the kinetics, and another Au 26Cd 5 nanocluster was also obtained after the conditions were changed in the same reaction, which could transfer to Au 11Cd in a two-way style. Both alloy nanoclusters can photocatalyze the production of singlet oxygen ( 1O 2) and exhibit enhanced efficiencies in photocatalyzing two kinds of organic oxidations involving singlet oxygen compared with their non-alloyed mother nanoclusters, indicating that the Cd-doping might be an efficient way to enhance the photocatalysis performance of gold nanoclusters and metal nanoclusters are promising photocatalysts for organic oxidation involving singlet oxygen. 相似文献
12.
The adsorption behavior of pyrrole molecule with external surface of (5.0) on zigzag aluminum nitride nanotube (AlNNT) was studied using density functional theory calculations. It was found that the adsorption energy ( Ead) of pyrrole on the surface of pristine nanotubes is about–11.99 kcal/mol. However, when nanotubes have been doped with P atom, the adsorption energy of pyrrole was increased. Calculation showed that for the phosphorus-doped nanotube the adsorption energy range is about–9.04 to?12.80 kcal/mol. AlNNT is a suitable adsorbent for pyrrole, so it can be used in adsorption and separation processes involving pyrrole. The doped AlNNT can potentially be used for pyrrole sensors for detection in environmental systems. 相似文献
13.
In this work, the Ni n ( n = 2–10) nanoclusters were investigated to design new catalysts for the selective hydrogenation of acetylene. Our results show that among the Ni n nanoclusters, the Ni 6 nanocluster can be used as a catalyst in the reactions of hydrogenation. In the presence of the Ni 6 nanocluster, the Ea of the forward step in the reaction of conversion of vinyl to ethylene was 21.21 kJ/mol lower than that of the reverse step in the reaction of conversion of acetylene to vinyl. Also, the Ea of the forward step in the reaction of conversion of ethyl to ethane was 96.59 kJ/mol higher than that of the reverse step in the reaction of conversion of ethylene to ethyl. According to the obtained results, the Ni 6 nanocluster can selectively act in the hydrogenation of a mixture of acetylene and ethylene. 相似文献
14.
Anatase TiO 2 surfaces, whether oxidised or hydroxylated, can be modified by nanoclusters of SnO and MgO to give a red shift in light absorption, enhanced charge separation and high reducibility. 相似文献
15.
Nitrous oxide (N 2O) adsorption on the pristine and Stone–Wales (SW)-defected hexagonal BN nanosheets were investigated using density functional calculations including dispersion correction. It was found that N 2O is weakly adsorbed on the pristine sheet ( h-BN) through van der Waals interaction with adsorption energy of ?1.2 kcal/mol. SW-defected sheet was found to be more reactive toward N 2O molecule having no significant change in electronic properties. However, the formation of B–B and N–N bond pairs in SW-defected sheet can be avoided, if there is a C–C pair doped in sheet (C 2-SW- h-BN). In this case, a strong adsorption is found due to large adsorption energy (?23.7 kcal/mol) and short bond length compared to the SW- h-BN complex. Interestingly, it was indicated that the N 2O molecule could be reduced into the N 2 on the C 2-SW- h-BN. 相似文献
16.
The development of efficient and cost-effective electrocatalysts for oxygen evolution reaction (OER) is crucial for the overall water splitting. Herein, we prepared a highly exposed NiFeO x ultra-small nanoclusters supported on boron-doped carbon nonotubes catalyst, which achieves a 10 mA/cm 2 anodic current density at a low overpotential of 213 mV and the Tafel slope of 52 mV/dec in 1.0 mol/L KOH, superior to the pristine NiFeO x-CNTs and other state-of-the-art OER catalysts in alkaline media. A combination study (XPS, sXAS and XAFS) verifies that the local atomic structure of Ni and Fe atoms in the nanoclusters are similar to NiO and Fe 2O 3, respectively, and the B atoms which are doped into the crystal lattice of CNTs leads to the optimization of Ni 3d e g orbitals. Furthermore, in-situ X-ray absorption spectroscopies reveal that the high valence state of Ni atoms are served as the real active sites. This work highlights that the precise control of highly exposed multicomponent nanocluster catalysts paves a new way for designing highly efficient catalysts at the atomic scale. 相似文献
17.
This work describes a potential selective adsorption of epigallocatechin gallate by Ga-doped TiO 2 nanoparticles (NPs) and showed excellent adsorption (~99%) and desorption capacity even after the 7th run. The work reports about a surfactant mediated template based synthesis of both pristine and Ga-doped TiO 2 mesoporous NPs to study the adsorption behavior EGCG. EGCG is the most abundant and bio-active compound capable of showing free radical scavenging activity, anticancer, antibacterial, and several other physiological functions. Therefore, extraction of EGCG is highly desirable for incorporation in food items that can effectively increase their nutritional and medicinal values. The pore diameter of the synthesized materials was found to be in the range 8.76–10.38 nm and the specific surface area was found to be around 25.80–58.72 m 2/g. The particle size decreased from 25 nm to 15 nm in presence of Ga. A mixture of anatase and brookite phase was observed for all the synthesized TiO 2 NPs. The band gap value initially (3.40 eV) decreased in presence of minute amounts of Ga (3.44 eV) but then increased (3.59 eV) with the increase of Ga percentage. The point of zero charge (PZC) value of the materials lies in the range of 6.6–7.2. The adsorption study was carried out at different pH (1, 3, 5, 7 and 9) with variation of shaking time (1 h, 3 h, 5 h and 7 h). The material containing maximum Ga in the Ga-doped set (Set 3 TiO 2 NPs) showed highest adsorption percentage (99.45%) in pH 1 medium after 5 h shaking. The adsorption isotherm and the kinetics follow the Langmuir model and pseudo-second order respectively. Desorption was studied under high energy gamma rays, shaking, sonication and UV irradiation. The highest desorption (~96%) was obtained with sonication for 30 min. 相似文献
18.
Covalent functionalization of a ZnO nanocluster with thiophene molecule was studied by means of density functional theory calculations. The obtained results show that the molecule is physically adsorbed on the surface of nanocluster with adsorption energies in the range of ?0.33 to ?0.42 eV. In this study, 2η-C 4H 4S–Zn 12O 12 cluster is the most stable adsorption among all thiophene adsorption configurations. Accordingly, HOMO–LUMO energy gap of the nano-cluster is changed about 0.24 to 0.72 % using the DFT calculations. The values of charge transfer shows that π-back bonding exists for 2η and 5η bonding modes. Present results might be helpful to provide an effective way to modify the Zn 12O 12 properties for further applications such as generation of the new hybrid compounds. 相似文献
19.
The effects of doping heteroatoms on the structure, electronic and adsorption properties of graphene are investigated using density functional theory calculations. Six different doped graphenes (with Al, B, Si, N, P, and S) are considered, and to obtain the interaction and adsorption properties, three sulfur-containing molecules (H 2S, SO 2, and thiophene) were interacted with selected graphenes. The adsorption energies ( E ad) in the gas phase and solvents show the exothermic interaction for all complexes. The maximum E ad values are observed for aluminum doped graphene (AG) and silicon doped graphene (SiG), and adsorption energies in the solvent are not so different from those in the gas phase. NBO calculations show that the AG and SiG complexes have the highest E (2) interaction energies and simple graphene (G) and nitrogen doped graphene (NG) have the least E (2) energies. Population analyses show that doping heteroatoms change the energy gap. This gap changes more during the interaction and these changes make these structures useful in sensor devices. All calculated data confirm better adsorption of SO 2 by graphenes versus H 2S and thiophene. Among all graphenes, AG and then SiG are the best adsorbents for these structures. 相似文献
20.
We report a new strategy in which a thiolate-protected Ag 25 nanocluster can be doped with open d-shell group 8 (Ru, Os) and 9 (Ir) metals by forming metal hydride (RuH 2, OsH 2, IrH) superatoms with a closed d-shell. Structural analyses using various experimental and theoretical methods revealed that the Ag 25 nanoclusters were co-doped with the open d-shell metal and hydride species to produce superatom-in-superatom nanoclusters, establishing a novel superatom doping phenomenon for open d-shell metals. The synthesized superatom-in-superatom nanoclusters exhibited dopant-dependent photoluminescence (PL) properties. Comparative PL lifetime studies of the Ag 25 nanoclusters doped with 8–10 group metals revealed that both radiative and nonradiative processes were significantly dependent on the dopant. The former is strongly correlated with the electron affinity of the metal dopant, whereas the latter is governed predominantly by the kernel structure changed upon the doping of the metal hydride(s). 相似文献
|