Al12N12 Nanocage Research Articles

Copper-doped Al12N12 nano-cages: potential candidates for nonlinear optical materials

DFT calculations have been performed to study geometric, electronic and NLO properties of copper-doped Al12N12 nano-cages. Doping of copper significantly reduces HOMO–LUMO gap of the nano-cages. The most prominent change in E g is observed for Cu@R6 (copper at the center of the six-membered ring), where E g is reduced by 52% of the original value. Total and partial densities of states have been plotted for all the structures revealing that a new HOMO has appeared between the original frontier molecular orbitals of Al12N12. Polarizabilities and hyperpolarizabilities show manifold increase (α = 418 au and β 0 = 1.8 × 104 au for Cu@R6) than pure Al12N12. TD-DFT calculations have been performed to obtain crucial excited states to account for the high hyperpolarizability values. The hyperpolarizability trend estimated from the two-level method and DFT calculations correlates nicely. The hyperpolarizability trend is justified nicely from the decreased E g. These findings designate such doped nano-cages as excellent candidates for their potential applications in electronic devices.

Binding affinity and permeation of X12Y12 nanoclusters for helium and neon

Helium and neon are two most inert noble gases, and they resist to binding with any surface. Continuous strides are being made to explore materials capable of binding with helium and neon. In this report, inorganic fullerenes are studied for their ability to adsorb and encapsulate helium and neon atoms. Both endohedral and exohedral complexes of X12Y12 with helium and neon are considered. Moreover, interconversion of exohedral and endohedral complexes is explored through an unprecedented approach where noble gases translate into the nano-cage through boundary crossing. The translation of He and Ne through the surface of X12Y12 (X=B, Al and Y=N, P) nano-cages (permeability of the nano-cage) is studied theoretically at B971 method of density functional theory. The kinetic barrier for encapsulation of helium and neon is obtained through scanning potential energy surface for motion of He/Ne through hexagons of the nano-cage. The translation of He and Ne is not feasible process at room temperature however, permeation selectivity can be achieved with controlled temperature. The effect of temperature n the boundary crossing barrier is also explored. The estimate of stabilities of exohedral and endohedral complexes of He and Ne with X12Y12 nano-cages is obtained through binding energy analysis. The exohedral binding of He/Ne with X12Y12 nano-cages is a favorable process whereas the encapsulation is thermodynamically unfavorable except for Ne in AlP nano-cage. The highest interaction energy is observed for exohedral doping of Ne with AlN nano-cage (−4.86kcalmol−1) which is comparable to Ne binding with highly electrophilic Be(CN)2. Adsorption/encapsulation energies of noble gases on/in nano-cages show strong correlation with the size of the nano-cage. The interaction energies at B97-1 method are also compared with those from M05-2X, B3LYP-D2 and PBE-D2 methods. SAPT analysis is also performed for evaluating the components of interaction energies. Electronic structures of nano-cages including energies of HOMO, LUMO, HOMO-LUMO gap, and excitation energies are analyzed. Electronic properties of endohedral X12Y12 complexes are remarkably different than those of exohedral complexes. The H-L gaps for exohedral complexes are almost comparable to bare X12Y12 nano-cages; however, the endohedral complexation causes significant increase in the H-L gap.

DFT study of the adsorption of H2O2 inside and outside Al12N12 nano-cage

The adsorption of hydrogen peroxide (H2O2) molecule on the outer and inner surfaces of Al12N12 nano-cage in terms of energetic, geometric, and electronic properties has been investigated using the density functional theory (DFT) calculations by B3LYP-D and M06-2X methods and 6-31G** basis set. It has been found that H2O2 molecule can be strongly chemisorbed (−3.45 eV) over the outer surface of the Al12N12 nanocage, where the adsorption energy depending upon its orientation with the nano-cage. Moreover, the adsorption of two H2O2 molecules on the outside surface of adsorbent is about −2.05 eV, while the adsorption of the molecule trapped inside adsorbent is about −1.81 eV. It was found that the H2O2 adsorption on the outer and inner surfaces of Al12N12 nano-cage leads to slightly lower energy gap and increasing the dipole moment of adsorbent.

Adsorption properties of acetylene and ethylene molecules onto pristine and nickel-decorated Al12N12 nanoclusters

We present here theoretical results on adsorption of two important industrial gases (C2H2 and C2H4) on free Al12N12 and Ni-decorated Al12N12 fullerene-like nanoclusters. Binding energies have been calculated with B3LYP and wB97XD methods of density functional theory. The binding energies were corrected for the basis set superposition error (BSSE) for 6-31G (d,p) basis set. Despite both molecules could be adsorbed on the surface of free Al12N12 with moderate binding energies of ∼ −37 (BSSE corrected: −25.7) kJ/mole for ethylene and ∼−58 (BSSE corrected: 44.6) kJ/mole for acetylene, based on wb97xd functional, however much strong interaction is achieved for Ni-decorated nano-cages over pure Al12N12. Adsorption energy of acetylene varies depending on the position of nickel decoration whereas the adsorption of ethylene is independent of the position of nickel decoration. The adsorption energies for acetylene and ethylene on Al12N12 nano-cage range from −294 to −410 (−202.1 to −281.3, BSSE corrected) kJ/mol. Along with high values of adsorption energy for Ni-decorated Al12N12 nano-cage, we found relatively low interaction distance, and high orbital hybridization upon adsorption of mentioned molecules on the surface Ni-AlN. Results of charge analyses show that upon adsorption of these molecules on free Al12N12, it acts as p-type semiconductor which interestingly, changes to n-type semiconductor when nickel is decorated on its surface.

Al12CN11 nano-cage sensitive to NH3 detection: A first-principles study

We investigated the adsorption ability of NH3 molecule on the outer surfaces of Al12N12, Al16N16, and Al12CN11 nano-cages using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations. The calculations represent that the NH3 molecule can be chemically adsorbed on the top of aluminum atoms in Al12N12 and Al16N16 nano-cages with the energies of −1.38 and −1.30 eV, respectively, indicating that the nature of these interactions are of the covalent characteristic. After the NH3 adsorption on the Al12CN11, the electronic and optical properties of the nano-cage and the atomic charge in the some of the nearby Al and N atoms around C atom was dramatically changed. Thus, the Al12CN11 can be utilized as a novel material for the detection of NH3 molecule owing to significant changes observed in their electrical conductivity.

Coordination of nickel atoms with Al12X12 (X = N, P) nanocages enhances H2 adsorption: A surface study by DFT

Density functional theory (DFT) calculations have been performed to study the adsorption of hydrogen on the surface of pristine and nickel decorated Al12N12 and Al12P12 nano-cages. Decoration of nickel on the surface of nano-cages delivers four distinct geometries. Hydrogen adsorption is studied on the surface of Ni-decorated Al12X12 (X = N, P) in these four geometries (named as P1, P2, P3, and P4). Calculations reveal very weak physisorption of H2 on pristine nano-cages while significant enhancement in its adsorption properties is found upon using Ni-X12Y12 nano-cages. The hydrogen adsorption on Ni-Al12N12 nano-cage is in order of P2 > P3 > P4 > P1, whereas the order of adsorption energies on Ni-Al12P12 is P2 > P1 > P3 > P4. Ni complexation with Al12N12 shows considerably higher potential for H2 adsorption compared to Al12P12. We used natural bond orbital (NBO), molecular dipole moment, density of states (DOS) and frontier molecular orbitals analyses to observe the changes in the electronic structure of Ni-Al12X12 nano-cages on adsorption of H2.

Selective detection of toxic cyanogen gas in the presence of O2, and H2O molecules using a AlN nanocluster

The interaction of cyanogen molecule with Al12N12 nanocage has been studied using density functional theory (DFT) at CAM-B3LYP/6-31+G(d) level. Geometric, electronic structure and natural bond orbitals (NBO) analysis display that adsorption of cyanogen onto exterior surface of Al12N12 is physisorption with adsorption energy (Eads) equal to −55.36 kJ/mol. UV–vis study shows a high intensity peak in 388.9 nm due to interaction of gas with nanocage. It is expected that Al12N12 will be used in designing novel materials for potential applications to detect toxic cyanogen molecule.

Adsorption of pyrrole on Al12N12, Al12P12, B12N12, and B12P12 fullerene-like nano-cages; a first principles study

Adsorption of pyrrole on the surfaces of four X12Y12 semiconductors (Al12N12, Al12P12, B12N12, and B12P12) is studied through density functional theory (DFT) calculations at B3LYP/6-31G(d,p) level of theory. The highest interaction energy is calculated for the adsorption of pyrrole on the surface of Al12N12 nano-cage. The adsorption energies of pyrrole on Al12N12, Al12P12, B12N12, and B12P12 are −64.6, −42.6, −12.0, −9.2 kJ mol−1, respectively. Pyrrole acts as an electron donor and adsorbs at the electrophilic site of nano-cage. Charge transfer to aluminum nano-cages is higher than to boron nano-cages. Changes in electronic properties such as band gap, Fermi level, and densities of states are also analyzed in order to better understand the sensing abilities of nano-cages for pyrrole molecule. Band gaps of aluminum nano-cages (Al12N12 and Al12P12) are unaffected by adsorption of pyrrole because of comparable effect on HOMOs and LUMOs. On the other hand, band gaps of boron nano-cages are significantly reduced on adsorption of pyrrole. Boron nano-cages are better sensor for pyrrole molecule despite their lower binding energies.

Detailed surface study of adsorbed nickel on Al12N12 nano-cage

The geometries and electronic structures of Ni-adsorbed Al12N12 (AlN) nano-cage are studied by density functional theory. A number of different structures varying in the position and orientation of nickel on the surface of the nano-cage are studied. Binding energies, band structures, total density of states, natural bond orbital charges, and electron density differences of Ni-adsorbed Al12N12 nano-cage were calculated, and analyzed in comparison with pure AlN nano-cage. The adsorption energies are in the range of (−110)–(−113) kcalmol−1 for three adsorption sites (P1–P3), and about −86kcalmol−1 for P4. High binding energies for these geometries suggest strong chemisorption of nickel on AlN nano-cage. Moreover, dissociation of AlN bond is observed concurrent with the formation of NiAl and NiN bonds when the Ni atom is adsorbed on the nano-cage. Results from the calculations also reveal that there is significant charge transfer from the nano-cage to the metal atom which changes the location of HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) resulting in reductions in the Egap (EHOMO-ELUMO). The HOMO-LUMO gap for P4 geometry is 1.79eV which is much lower than the band gap for pure AlN nano-cage (3.93eV). The band gap for P1, P2 and P3 geometries is 2.90, 2.79 and 3.18eV, respectively. The decrease in band gap is attributed to the push of outer d electrons of the transition metals to become more diffuse like. The HOMOs in all geometries have densities on Ni atom whereas the densities in LUMO are distributed on the entire skeleton. The results revealed that Ni adsorption provides N-type conduction which makes it an ideal adsorbent for practical applications in magnetism, catalysis and other areas. Reactivity descriptors indicate an increase in electrophilic character of Ni-adsorbed nano-cages compared to pure AlN nano-cage. The electron affinity and softness are highest for P4 geometry whereas the lowest ionization potential and hardness are calculated for P4.

Ambient carbon dioxide capture by different dimensional AlN nanostructures: A comparative DFT study

Strong binding of an isolated carbon dioxide molecule over three different aluminium nitride (AlN) nanostructures (nanocage, nanotube and nanosheet) is verified using density functional calculations. Equilibrium geometries, electronic properties, adsorption energies and thermodynamic stability of each adsorbed configuration are also identified. Optimized configurations are shown at least one corresponding physisorption and chemisorption of CO2 molecule over different AlN nanostructures. Also, the effect of chirality on the adsorption of CO2 molecule is studied over two different finite-sized zigzag (6,0) and armchair (4,4) AlN nanotubes. It is found that the electronic properties of the Al12N12 nanocage are more sensitive to the CO2 molecule than other AlN nanostructures. This indicates the significant potential of Al12N12 nanocage toward the CO2 adsorption, fixation and catalytic applications in contrast to other AlN nanostructures.

Adsorption properties of hydrazine on pristine and Si-doped Al12N12 nano-cage

GRAPHICAL ABSTRACT

A comparative density functional theory study of guanine chemisorption on Al12N12, Al12P12, B12N12, and B12P12 nano-cages

Density functional theory (DFT) calculations have been performed for adsorption of guanine (a nucleobase) on the surface of Al12N12 (AlN), Al12P12 (AlP), B12N12 (BN), and B12P12 (BP) nano-cages. The interaction of guanine with nano-cages is highly exothermic (chemisorption), and the adsorption energies are in order of AlN > AlP > BN > BP. Although AlN has the highest adsorption energy; however, BN and BP show more changes in electronic property upon adsorption of guanine. The results of charge analysis, density of states (DOSs), and frontier molecular orbital, confirm a distinguished orbital hybridization upon adsorption of guanine, which suggest potential application of BN as biochemical adsorbent for guanine.

A theoretical study on superalkali-doped nanocages: unique inorganic electrides with high stability, deep-ultraviolet transparency, and a considerable nonlinear optical response.

By doping an Al12N12 nanocage with superalkali Li3O, a series of Li3O@Al12N12 compounds were theoretically designed and investigated for the first time. Computational results reveal that these species contain diffuse excess electrons, and thus can be regarded as inorganic electrides of a new type. As expected, these proposed electrides possess considerable first hyperpolarizabilities (β0) up to 1.86 × 10(7) au. In particular, the lowest-energy Li3O@Al12N12 exhibits high stability and excellent deep-ultraviolet transparency. Moreover, the effects of superalkali and nanocage subunits on the NLO responses of M3O@Al12N12 (M = Li, Na, K) and Li3O@X12Y12 (X = B, Al; Y = N, P) are systemically investigated. Results show that the respective substitution of Na3O and B12P12 for Li3O and Al12N12 can bring a larger β0 for such electrides. This study may be significant in terms of providing an effective strategy to design thermally stable inorganic electrides as potential high-performance NLO molecules.

Al12N12 nanocage as potential adsorbent for removal of acetone from environmental systems

The electronic and geometrical structures of acetone adsorption on Al12N12 nanocage have been investigated using DFT calculations, by means of B3LYP functional with 6-31G* and 6-31 + G*basis sets. The results showed that the acetone binds to the Al atom of Al12N12 with adsorption enthalpies of −119.12 kJ/mol (6-31G* basis set) and about −116.94 kJ/mol (6-31 + G* basis set) for the first acetone and −116.57 kJ/mol (6-31G* basis set) and about −113.89 kJ/mol (6-31 + G* basis set) for the second one (per each molecule). On the basis of calculated density of states, adsorption of acetone molecule on the Al12N12 surface induces some changes in electronic properties of the nanocage. For the systems, the field emission properties are improved upon the acetone adsorption and the thermodynamic values indicated that this process is exothermic. On the basis of the results, Al12N12 nanocage can be a promising candidate for adsorption of acetone from environmental systems.

Efficient dehydrogenation of formic acid using Al12N12 nanocage: A DFT study

We have studied the adsorption and decomposition of formic acid (HCOOH) on the surface of Al12N12 fullerene-like nanocage using density functional theory. Different adsorption modes were found for HCOOH on the Al12N12, i.e. molecular and dissociative monodentate or bidentate adsorption. Three reaction pathways were proposed to understand gas-phase HCOOH decomposition on the Al12N12 nanocage. Our results reveal that for the decomposition of HCOOH into CO2 and H2, the most favorable pathway should be the CH bond activation reaction. The reaction energies and the activation barriers obtained here suggest that for the dissociative adsorption configuration on the Al12N12 surface, the rate-determining step is the CH bond breaking.

Al12N12 nanocage as a potential sensor for phosgene detection

To find a novel sensor for phosgene molecules, phosgene adsorption on Al12N12 nanocage was studied by using density functional calculations in terms of geometry, Gibbs free energy, energy gap, enthalpy changes, vibrational frequencies, work function, molecular electrostatic potential surface, and density of state analysis. It was found that the electronic properties of the Al12N12 nanocage are very sensitive to the presence of phosgene molecules so that the energy gap of the nanocage is changed about 31% after the adsorption process. Based on calculated results, the Al12N12 nanocage is expected to be a promising novel sensor for phosgene molecules without manipulating its structure through doping, chemical functionalization, etc.

Doping the Alkali Atom: An Effective Strategy to Improve the Electronic and Nonlinear Optical Properties of the Inorganic Al12N12 Nanocage

Under ab initio computations, several new inorganic electride compounds with high stability, M@x-Al12N12 (M = Li, Na, and K; x = b66, b64, and r6), were achieved for the first time by doping the alkali metal atom M on the fullerene-like Al12N12 nanocage, where the alkali atom is located over the Al-N bond (b66/b64 site) or six-membered ring (r6 site). It is revealed that independent of the doping position and atomic number, doping the alkali atom can significantly narrow the wide gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) (EH-L = 6.12 eV) of the pure Al12N12 nanocage in the range of 0.49-0.71 eV, and these doped AlN nanocages can exhibit the intriguing n-type characteristic, where a high energy level containing the excess electron is introduced as the new HOMO orbital in the original gap of pure Al12N12. Further, the diffuse excess electron also brings these doped AlN nanostructures the considerable first hyperpolarizabilities (β0), which are 1.09 × 10(4) au for Li@b66-Al12N12, 1.10 × 10(4), 1.62 × 10(4), 7.58 × 10(4) au for M@b64-Al12N12 (M = Li, Na, and K), and 8.89 × 10(5), 1.36 × 10(5), 5.48 × 10(4) au for M@r6-Al12N12 (M = Li, Na, and K), respectively. Clearly, doping the heavier Na/K atom over the Al-N bond can get the larger β0 value, while the reverse trend can be observed for the series with the alkali atom over the six-membered ring, where doping the lighter Li atom can achieve the larger β0 value. These fascinating findings will be advantageous for promoting the potential applications of the inorganic AlN-based nanosystems in the new type of electronic nanodevices and high-performance nonlinear optical (NLO) materials.

Ab initio study of the NO2 and SO2 adsorption on Al12N12 nano-cage sensitized with gallium and magnesium

The chemisorption of various gases, i.e., NO2 and SO2 gases, upon the outer sidewalls of the pure, Ga-, and Mg-doped Al12N12 have been investigated via first-principles calculations. The estimated adsorption energies corresponding to the most stable configurations of NO2 and SO2 on Al12N12 are equal to −1.28 and −2.77eV, respectively. Our theoretical investigation demonstrates that the presence of SO2 and NO2 on the Ga- and Mg-doped Al12N12 lead to significant changes in the structural and electronic properties of the Al12N12. Our calculations show that the interactions of gas molecules on the surface of Ga- and Mg-doped Al12N12 reveal significant charges transfer from nano-cage to the NO2 and SO2 attributed to chemical adsorptions of these molecules. Besides, the Mg-doped Al12N12 cluster has high sensitivity to the presence of SO2 and NO2 molecules.

Quantum chemical study of fluorinated AlN nano-cage

Adsorption of 1, 2, 3, and 12 F atom(s) on the surface of Al12N12 nanocluster has been investigated using density functional theory. It has been found that the F atom strongly prefers to be adsorbed on Al site of the cluster rather than N one with the average Gibbs free energy change of −93.2 to 98.0kcal/mol at 298K and 1atm. Average enthalpy change of the reaction is slightly increased by increasing the number of F atoms. The F adsorption considerably influences electronic properties of the cluster so that it is transferred from intrinsic semiconductor to p-type one. HOMO/LUMO energy gap of the cluster is narrowed and the Fermi level is dramatically shifted from −4.50eV in the bare cluster to lower energies upon the F adsorptions along with increased work function of the cluster. This results in raised potential barrier of the electron emission for the cluster and hence hindering its field emission. Moreover, it has been shown that the following reaction may occur spontaneously at room temperature and 1atm: Al12N12+6F2→Al12N12F12.

Selective function of Al12N12 nano-cage towards NO and CO molecules

Equilibrium geometries, stabilities, and electronic properties of toxic CO and NO molecule adsorptions on the exterior surface of Al12N12 nano-cage were investigated through density functional calculations. The obtained most stable adsorption configurations are those in which the C and N atoms of CO and NO are closed to an Al atom of the cluster, respectively, accompanied with the adsorption energies of −0.58 and −0.46eV. It was revealed that the electrical conductivity of the cluster may be increased upon the NO adsorption, being insensitive towards CO adsorption. Thus, the Al12N12 cluster might selectively detect the NO molecule in the presence of CO molecules.