Nitride Clusters Research Articles

Complexation of Sc3N@C80 as a model rare-earth nitride cluster fullerene with different crystallizing agents: A DFT analysis

We report on a computational study (at the PBE-D2/DNP level of DFT) of the bonding strength, geometry and selected electronic properties of the noncovalent dyads between different crystallizing agents (CAs) and the scandium nitride cluster (Sc3N) encapsulated by Ih-C80 endohedral fullerene (Sc3N@C80). The crystallizing agents studied were nickel(II) octaethylporphyrin (NiOEP), decapyrrylcorannulene (DPC), Zn tetraphenyl porphyrin (ZnTPP), and Ni tetramethyldibenzo-tetraazaannulenato (NiTMTAA). The strength of noncovalent interactions between the NCF and CAs decreases in the following order: Sc3N@C80 + NiOEP-in > Sc3N@C80 + DPC > Sc3N@C80 + NiOEP-out > Sc3N@C80 + ZnTPP > Sc3N@C80 + NiTMTAA-me > Sc3N@C80 + NiTMTAA-bz. The Sc⋯CC80 distances show negligible changes for the NCF in all the cases. The inner cluster Sc3N remains always planar despite of the use of different CAs. Two general patterns of HOMO-LUMO distribution were found. The dominating one, found in all the dyads except for the two formed with NiOEP, is when no HOMO fraction is detected on Sc3N@C80 component, but instead solely on the corresponding CA; on the contrary, the LUMO is concentrated on NCF.

Achieving ultrahigh hole mobility in hydrogen-terminated diamond via boron nitride modifications

Wide-bandgap semiconductors with high carrier mobility are in great demand for high-power radio-frequency applications. In the past decades, extensive efforts have been devoted to investigating the carrier transport properties of hydrogen-terminated diamond (H-diamond), however, achieving its high hole mobility remains a challenge, thereby limiting the development of diamond electronic devices. Herein, we propose a novel strategy to increase the hole mobility of H-diamond by boron nitride (BN) clusters modifications. Amorphous BN clusters were deposited on high-quality H-diamond surfaces using magnetron sputtering. The modified H-diamond exhibits an ultrahigh hole mobility of 1100 cm2 V−1 s−1, over 10-fold higher than that of H-diamond prior to BN modification. Moreover, the BN-modified H-diamond also exhibits outstanding high-temperature tolerance and excellent thermal stability benefitting from the passivation effect of BN. At 380 K, it still maintains a hole mobility of 385 cm2 V−1 s−1. Even after annealing at 350 K for over 8 h, there are no noticeable variations in its carrier transport properties. The hole mobility enhancing mechanism and the factors influencing carrier transport properties of the BN-modified H-diamond are discussed using first principles calculations analysis. The developed BN-modified H-diamond opens up new possibilities for diamond-based radio-frequency electronic devices operating in challenging temperature environments.

Transition Metal/Lanthanide-Nitrogen Double Bonds Co-stabilized in a Carbon Cage.

Metal-nitrogen double bonds have been commonly reported for conventional metal complexes, but the coexistence of both transition metal-nitrogen and lanthanide-nitrogen double bonds bridged by nitrogen within one compound has never been reported. Herein, by encapsulating a ternary transition metal-lanthanide heteronuclear dimetallic nitride into a C84 fullerene cage, transition metal-nitrogen and lanthanide-nitrogen double bonds are costabilized simultaneously within the as-formed clusterfullerene TiCeN@C1(12)-C84, which is a representative heteronuclear dimetallic nitride clusterfullerene. Its molecular structure was unambiguously determined by single-crystal X-ray diffraction, revealing a slightly bent μ2-bridged nitride cluster with short Ti-N (1.761 Å) and Ce-N (2.109 Å) bond lengths, which are comparable to the corresponding Ti=N and Ce=N double bonds of reported metal complexes and consistent with the theoretically predicted values, confirming their coexistence within TiCeN@C1(12)-C84. Density functional theory (DFT) calculations unveil three-center two-electron (3c-2e) bonds delocalized over the entire TiCeN cluster, which are responsible for costabilization of Ti=N and Ce=N double bonds. An electronic configuration of Ti4+Ce3+N3-@C84 4- is proposed featuring an intramolecular four-electron transfer, drastically different from the analogous actinide dimetallic nitride clusterfullerene (U2)9+N3-@C80 6- and trimetallic nitride clusterfullerene (Sc2)6+Ti3+N3-@C80 6-, indicating the peculiarity of 4-fold negatively charged fullerene cage in stabilizing the heteronuclear dimetallic nitride cluster.

Predicting Binding Energies and Electronic Properties of Boron Nitride Fullerenes Using a Graph Convolutional Network.

As isoelectronic counterparts of carbon fullerenes, medium-sized boron nitride clusters also prefer cage structures composed of even-sized polygons. As the cluster size increases, the number of cage isomers grows rapidly, and determining the ground state structure requires a tremendous amount of DFT calculations. Herein, we develop a graph convolutional network (GCN) that can describe the energy of a (BN)n cage by its topology connection. We define a vertex feature vector on a dual polyhedron by the permutation of the neighbor vertices' degree and aggregate the information on vertices by two graph convolutional layers to learn the local feature of the dual polyhedron. The GCN is trained on (BN)28 and subsequently tested on (BN)23 and (BN)24 data sets, which satisfactorily reproduce the order of isomer energies from DFT calculations. We further employ the trained GCN to predict the ground state structures within the size range of n = 25-32, which agree well with DFT results. Using the same GCN framework, we also successfully trained the highest-occupied or lowest-unoccupied orbital energies of (BN)28 isomers. The present graph convolutional network establishes a direct mapping between the topological connection and the energetic or electronic properties of a cage-like cluster or molecule.

Density functional theory calculations on the structures and electronic properties of boron nitride clusters toward formaldehyde

Density functional theory calculations on the structures and electronic properties of boron nitride clusters toward formaldehyde

A quadruple-strategy of modification on carbon nitride boosts oxygen reduction for high performance photocatalytic hydrogen peroxide production

This paper reports a quadruple-strategy for material design, simultaneously applying morphology control, group modification, defect engineering and alkali metal doping to the design of catalysts, and successfully constructing irregular clusters of carbon nitride (pMNK-CN) with excellent photogenerated carrier separation performance and structural stability. The pMNK-CN is an irregular flower cluster-like morphology with a nanosheet structure on the surface, and the repolymerization process of the prepolymer in the microvoid of the metal salt gives it an open pore structure. With the help of essential characterization, it was confirmed that the heptazine unit in the backbone underwent partial decomposition due to the etching of metal salts at high temperatures, reducing the overall polymerization and introducing cyano and nitrogen vacancies. Meanwhile, the potassium ion embedded in the lattice can induce the growth of ordered structures and thus improve the short-range order. The pMNK-CN possesses a hydrogen peroxide production efficiency of 240.0 μmol·g−1·h−1 in pure water, which is 31 times higher than that of bulk carbon nitride. And the apparent quantum efficiencies of pMNK-CN in the 380 and 420 nm bands are 17.5 % and 14.8 % in the presence of isopropanol. The effects of each modification strategies on the electronic structure of carbon nitride were investigated using First-Principles, and it was demonstrated that the multiple modification strategies synergistically enhanced the optical absorption, photogenerated charge separation efficiency, and lowered the reaction energy barrier, thus greatly contributing to the oxygen reduction to hydrogen peroxide performance.

Structures, stabilities and electronic properties of nitrogen dioxide adsorbed and embedded boron nitride clusters with different diameters

Structures, stabilities and electronic properties of nitrogen dioxide adsorbed and embedded boron nitride clusters with different diameters

Synthesisation, Fabrication, and Incorporation Techniques of MAX Phase and MXene Saturable Absorber in Passively Q-switched and Mode-locked All-fibre Laser Cavities: A Review

MAX phases and MXene have been introduced in passively pulsed-laser generation for their viability as substitutes to unadventurous saturable absorbers such as saturable absorber mirror, multi-wall and single-wall carbon nanotube, graphene, and transition metal dichalcogenides, contributing to both Q-switching and mode-locking tactics. Fundamental saturable-absorber features such as nonlinear saturable absorption, astonishing depth of modulation, flexibly tuneable bandgap, and high electron density around the Fermi level, establish MAX phases and MXene as formidable contenders with decent performance in the saturable absorber regime. Recent research works contributing to MAX Phases and MXene—particularly in nonlinear ultrafast optics—have shown an exponential increase, since MAX Phases and MXene are of the prime regime of 2D nanomaterials that offer vast combination options by the formation of metal nitride, metal carbide, or carbonitride clusters with a 2D layered structure, with special emphasis on fabrication and incorporation of saturable absorbers into laser cavities. This review critically summarises the advancement on the synthesis, fabrication, and incorporation of the MAX phases and MXene saturable absorbers, as well as the incorporation methodologies and techniques into all-fibre laser cavities configured either in linear or ring configuration, summing up the identified issues and challenges and discussing future perspectives of this novel material.

A first-principal study of pure and encapsulation boron nitride cluster with alkaline metals as the metformin drug carrier

Finding new drug-delivery materials has attracted considerable interest from many researchers in recent years. Herein, systematic investigation of the metformin interaction with the surface of pristine B12N12 and group I metals (Li, Na, and K) encapsulation nanoclusters was carried out at B3LYP/631++ (d, p) level of theory based on the DFT calculations. MF molecule has two nucleophilic sites, NH and NH2 groups. The trapping of Li, Na, and K atoms affected the HOMO–LUMO gaps of the considered configurations and the electronic properties of considered complexes. Besides, it is noticed that presence of alkali metals remarkably increased the absorption energies of MF-B12N12 to −2.14, −2.24, −2.30, and −2.38 for B12N12, Li@B12N12, Na@B12N12, and K@B12N12 respectively. In addition, DOS plots show a decrease in Egap by the addition of alkali metals and therefore an increase in reactivity of the considered configurations, which is confirmed by the decrease in total hardness.

DFT Analysis of the Electronic and Structural Properties of Lanthanide Nitride Cluster Fullerenes Ln3N@C80

We have undertaken a DFT study of the nitride cluster fullerenes (NCFs) Ln3N@C80 for the complete series of fourteen lanthanides plus lanthanum by using the PBE functional with the Grimme’s dispersion correction (PBE-D2). We tested the DN and DND basis sets, which are equivalent to 6-31G and 6-31G(d) Pople-type basis sets, respectively. Due to the known convergence problems when treating lanthanide-containing systems, only with the DN basis set was it possible to complete the calculations (geometry optimization and analysis of selected electronic parameters) for all the fifteen NCFs. We found that the bending of the Ln3N cluster increases as the ionic radius increases, in general agreement with the available X-ray diffraction data. The Ln3N cluster becomes more planar as the Ln–N bond length is contracted, and the C80 cavity slightly deforms. The HOMO-LUMO energies and distribution, as well as the charge and spin of the encapsulated metal ions, are analyzed.

Obtaining gallium nitride cluster for information transmission in optoelectronic communication lines

The paper proposes a method for obtaining light-emitting clusters of gallium nitride (GaN) on porous gallium arsenide (GaAs) substrates by treating the substrate with nitrogen atoms from a nitrogen RF plasma. The morphological and luminescent properties of the obtained structures were studied. Reasons for the possibility of using light-emitting GaN clusters for the manufacture of LEDs and their use in optoelectronic communication lines are provided. It was established that the photoluminescent properties of GaN clusters depend on the porosity of the GaAs substrate and the geometric dimensions of the formed clusters.

Oxygen‐modulated metal nitride clusters with moderate binding ability to insoluble Li2Sx for reversible polysulfide electrocatalysis

AbstractMultiphase sulfur redox reactions with advanced homogeneous and heterogeneous electrochemical processes in lithium–sulfur (Li–S) batteries possess sluggish kinetics. The slow kinetics leads to significant capacity decay during charge/discharge processes. Therefore, electrocatalysts with adequate sulfur‐redox properties are required to accelerate reversible polysulfide conversion in cathodes. In this study, we have fabricated an oxygen‐modulated metal nitride cluster (C‐MoNx‐O) that has a moderate binding ability to the insoluble Li2Sx for reversible polysulfide electrocatalysis. A Li–S battery equipped with C‐MoNx‐O electrocatalyst displayed a high discharge capacity of 875 mAh g−1 at 0.5 C. The capacity decay rate of each cycle was only 0.10% after 280 cycles, which is much lower than the control groups (C‐MoOx: 0.16%; C‐MoNx: 0.21%). Kinetic studies and theoretical calculations suggest that C‐MoNx‐O electrocatalyst presents a moderate binding ability to the insoluble Li2S2 and Li2S when compared to the C‐MoOx and C‐MoNx surfaces. Thus, the C‐MoNx‐O can effectively immobilize and reversibly catalyze the solid–solid conversion of Li2S2–Li2S during charge–discharge cycling, thus promoting reaction kinetics and eliminating the shuttle effect. This study to design oxygen‐doped metal nitrides provides innovative structures and reversible solid–solid conversions to overcome the sluggish redox chemistry of polysulfides.image

Guidelines for the synthesis of molybdenum nitride: Understanding the mechanism and the control of crystallographic phase and nitrogen content

Bulk (Mo2N) and supported molybdenum nitride (Mo2N/TiO2, Mo2N/CeO2) were synthesized by reduction-nitridation of bulk and supported MoO3 under a mixture of N2/H2. We investigated the mechanism of formation of molybdenum nitrides by coupling elemental analysis, in situ and ex situ XRD, Raman spectroscopy, in situ XPS/UPS spectroscopy and DFT calculation. We showed that it is possible to control the crystallographic phase and degree of nitridation (i.e. nitrogen vacancies) by adjusting the parameters of the synthesis, including the heating rate and final temperature, the nature, composition and flow of gas during reduction/nitridation and cooling. We demonstrated that β-Mo2N and γ-Mo2N go through the same intermediates: molybdenum bronze, MoO2 and Mo. The final crystallographic phase of the nitride depends mainly on the temperature rate and gas hourly space velocity employed during the synthesis, as they impact the crystallite size of the intermediates and the kinetics of reduction and nitridation. Molybdenum nitride clusters (<0.5 nm) are formed on TiO2.

Plasma-Assisted Dinitrogen Activation on Small Cobalt Clusters: Co4 N9 + with Enhanced Stability.

We have performed a study on the accommodation of nitrogen doping toward superatomic states of transition metal clusters. By reacting cobalt clusters with N2 in the presence of plasma radiation, a large number of odd-nitrogen clusters were observed, typically Co3 N2m-1 + (m=1-5) and Co4 N2m-1 + (m=1-6) series, showing N≡N bond cleavage in the mild plasma atmosphere. Interestingly, the Co3 N7 + , Co4 N9 + , and Co5 N9 + clusters exhibit prominent mass abundances. First-principles calculation results elucidate the stability of the diverse cobalt nitride clusters and find unique stability of Co4 N9 + with a swallow-kite structure of which four coordinated N2 molecules causes a significantly enlarged HOMO-LUMO gap, while the single N atom doping gives rise to superatomic states of 1S2 1P3 ||1D0 . We reveal an efficient dinitrogen activation strategy by reacting multiple N2 molecules with cobalt clusters under a plasma atmosphere.

Plasma-Assisted Dinitrogen Activation via Dual Platinum Cluster Catalysis: A Strategy for Ammonia Synthesis under Mild Conditions

Plasma-Assisted Dinitrogen Activation via Dual Platinum Cluster Catalysis: A Strategy for Ammonia Synthesis under Mild Conditions

Computational Density Functional Theory Investigation of Stability and Electronic Structures on Boron Nitride Systems Doped with/without Group IV Elements

In this paper, the stability as well as electronic structures of pure and group IV-substituted boron nitride (BN) cluster systems were investigated using Density Functional Theory (DFT) method. The results obtained from the DFT calculations found that the germanium-substituted BN model possessed the highest stability among all the group IV-substituted BN clusters. Although the energy gap values calculated were slightly different for all group IV-substituted single-layered BN clusters, the surface plots of HOMO and LUMO obtained were still the same. For the plots of molecular electrostatic potentials (MEPs), the nitrogen atom located in the middle of the pure BN system&nbsp; has the most negative electrostatic potentials. In the case of the group IV-substituted BN models, three atoms (i.e., carbon, silicon, and germanium) presented the most reactive sites for nucleophilic attack on the cluster systems. Mulliken atomic charges reported a similar trend as observed in MEPs. In the Mulliken scheme, the nitrogen atom located in the middle of the pure BN system&nbsp;possesses the highest negative charge. While three atoms (i.e., carbon, silicon, and germanium) showed the highest negative charges in the group IV-substituted BN model clusters.

15 N/14N isotopic exchange in the dissociative adsorption of N2 on tantalum nitride cluster anions Ta3N3−

Adsorption and activation of dinitrogen (N2) is an indispensable process in nitrogen fixation. Metal nitride species continue to attract attention as a promising catalyst for ammonia synthesis. However, the detailed mechanisms at a molecular level between reactive nitride species and N2 remain unclear at elevated temperature, which is important to understand the temperature effect and narrow the gap between the gas phase system and condensed phase system. Herein, the 14N/15N isotopic exchange in the reaction between tantalum nitride cluster anions Ta314N3− and 15N2 leading to the regeneration of 14N2/14N15N was observed at elevated temperature (393−593 K) using mass spectrometry. With the aid of theoretical calculations, the exchange mechanism and the effect of temperature to promote the dissociation of N2 on Ta3N3− were elucidated. A comparison experiment for Ta314N4−/15N2 couple indicated that only desorption of 15N2 from Ta314N415N2− took place at elevated temperature. The different exchange behavior can be well understood by the fact that nitrogen vacancy is a requisite for the dinitrogen activation over metal nitride species. This study may shed light on understanding the role of nitrogen vacancy in nitride species for ammonia synthesis and provide clues in designing effective catalysts for nitrogen fixation.

Group three nitride clusters as promising components for nanoelectronics

The real use of nanoelectronics with organic molecules as a replacement of conventional silicon technology faces many challenges because of complications in synthesis and fabrication processes, short stability, junction breakdown, large fabrication costs and environmental influences. The present work aims at proposing a novel alternative by studying the potential of ‘inorganic analogues of the organic components' in molecular electronics. In comparison to their organic counterparts, the higher structural rigidity in inorganic components provides a possible added value in being less susceptible to environmental influences. The structure as well as electronic and transport properties of group three nitride analogues of benzene molecules, namely, the X3N3H6 (X = B, Al and Ga) clusters are analysed and compared with benzene and with melamine, a graphitic carbon nitride (g-C3N4) material. A detailed density functional theory (DFT) investigation is performed for the structural and electronic properties, whereas a combined DFT and non-equilibrium Green's function approach is used for the transport properties. The electron delocalisation with overlapping electronic states, the influence of magnetic fields and favourable quantum chemical properties of Ga3N3H6 clusters make the man outstanding electronic component for future nanoelectronics applications.

Evolution of Ferromagnetic and Antiferromagnetic States in Iron Nitride Clusters FenN and FenN2 (n = 1-10).

First-principles density functional theory calculations on neutral and singly negatively and positively charged iron clusters Fen and iron nitride clusters FenN and FenN2 (n = 1-10) in the range of 1 ≤ n ≤ 10 revealed that there is a strong competition between ferromagnetic and antiferromagnetic states especially in the FenN20,±1 cluster series. This phenomenon was related to superexchange via a bridging N atom between two iron atoms in the FenN20,±1 cluster series and to a double superexchange effect via a Fe atom shared by two N atoms in the FenN20,±1 series. A thorough examination of the structure-energy-spin state relationships in these clusters is conducted, leading to new insights and confirmation of available experimental results on structural parameters and dissociation energetics. The bond energies of both nitrogen atoms in the FenN2 series are approximately the same. They weakly depend on the charge of the host cluster and fluctuate around 5.5 eV when moving along the series. The energy of N2 desorption is relatively small; it varies by about 1.0 eV and depends on the charge of the cluster. The experimental finding that N2 dissociates on the Fen+ clusters beginning with n = 4 was supported by the results of our computations. Our computed values of the Fen+-N bonding energies agree with the experimental data within the experimental uncertainty bars. It was found that the attachment of one or two N atoms does not seriously affect the polarizability, electron affinity, or ionization energy of the host iron clusters independent of the charge.

Diamond Boron Nitride: Pressure‐Induced Formation and Mechanical Properties of 2D Diamond Boron Nitride (Adv. Sci. 2/2021)

2D diamond boron nitride clusters are produced by inducing a sp2 to sp3 phase transition with the application of local pressure on atomically thin h‐BN on a SiO2 substrate, at room temperature, and without chemical functionalization, as demonstrated in article number 2002541 by Elisa Riedo and co‐workers. Molecular dynamics simulations, mechanical measurements, and Raman spectroscopy experiments show a metastable local rearrangement of the h‐BN atoms into diamond crystal clusters, which depends on the applied pressure and number of atomic layers.