Carbide Nanoclusters Research Articles

Exploring the Sensitivity of Bowl-shaped Silicon Carbide Nanocluster towards G-Series Nerve Agents: A Density Functional Theory Approach

Exploring the Sensitivity of Bowl-shaped Silicon Carbide Nanocluster towards G-Series Nerve Agents: A Density Functional Theory Approach

Density Functional Theory Studies on Boron Nitride and Silicon Carbide Nanoclusters Functionalized with Amino Acids for Organophosphorus Pesticide Adsorption

This study compares the properties of B12N12 and Si12C12 nanoclusters functionalized with tyrosine in the adsorption of organophosphorus pesticides, focusing on adsorption energy and electronic stability. The results indicate that B12N12/tyrosine exhibits more negative adsorption energies than Si12C12/tyrosine, suggesting stronger interactions and higher adsorption stability. Additionally, B12N12 demonstrates higher ionization energy and chemical hardness, enhancing its electronic stability during the adsorption process. In contrast, Si12C12 has higher electrophilicity and maximum electron transfer capacity, leading to greater variability in adsorption energy and more flexible electronic structure adjustments. These findings suggest that B12N12 nanoclusters have greater potential and application value as adsorption materials, particularly when modified with tyrosine. B12N12/tyrosine demonstrates higher stability and predictability in pesticide adsorption, making it more suitable for related applications.

Molybdenum carbide nanoclusters with ultrafast electron transfer ability promotes molecular oxygen selective electrocatalytic reduction to hydroxyl radicals for pollutant control

A treatment strategy of in situ generation and activation of hydrogen peroxide to degrade pollutants by the heterogeneous Fenton-like technology is promising for water pollution. However, the selective activation of oxygen to hydroxyl radicals (OH) by cathode materials is still challenging. Here, molybdenum carbide (MoC) supported on a heteroatoms-doped (N, P, S) carbon carrier catalyst was successfully prepared, which rapidly produced OH and degraded paracetamol (APAP) pollutants. A high APAP degradation efficiency with a specific energy consumption of 0.24 kWh g−1 TOC was achieved. After 10 sets of continuous operations, the APAP degradation rate remains unchanged. Combined with density functional theory calculations, molecular oxygen adsorption obtains one electron with proton hydrogen transfer to hydroperoxyl (OOH) on the MoC surface, and the adsorbed OOH directly activate into OH due to the ultrafast electron transfer ability of MoC. Differential charge density analysis also shows that Mo transfers electrons to O. This strategy provides a new idea for optimizing catalysts to improve the heterogeneous Fenton-like performance.

A Rational Design of Alkali Metal-Doped Germanium Carbide Nanoclusters for High Nonlinear Optical Response and Ultraviolet Transparency

A Rational Design of Alkali Metal-Doped Germanium Carbide Nanoclusters for High Nonlinear Optical Response and Ultraviolet Transparency

Structural, Non-linear optical response and ultraviolet transparency of superalkalis (Li3O, Na3O, K3O)-doped bowel shape silicon carbide nanoclusters

In the current study, the effect of superalkalis (Li3O, Na3O, and K3O) doping over bowl shaped silicon carbide (b-SiC) for geometrical, electronic and nonlinear properties has been investigated using DFT theory. The results revealed that doped b-SiC nanoclusters possess high thermodynamic stability as revealed from interaction energy up to −165.85 kcal/mol. The frontier molecular orbitals illustrate the occupation of electronic density in orbitals. Natural bond orbital charge analysis confirms the charge transfer from superalkalis to the b-SiC nanocluster. Furthermore, the electronic properties are rationalized from total density of states spectra. The highest first hyperpolarizability value (5979.99 au) is observed for isomer O of K3O@b-SiC complexes. The electronic excitation is analyzed through UV–VIS analysis. Two-level model describing the internal factors responsible for enhancement of NLO response is also studied. The present work gives a guideline for the synthesis of nonlinear optical materials with greater efficiencies which can be used as building blocks in the modern world of optoelectronics.

Exploring the second-order polarizability of copper doped silicon carbide nanocluster: toward a new NLO material

Nonlinear optical materials are widely used in optical and optoelectronic devices. The geometric, electronic, and NLO properties of copper-doped 2D silicon carbide nanoclusters (Cu@h-SiC) are investigated. The HOMO–LUMO gap (Eg) of the h-SiC nanocluster is significantly decreased by copper atom doping. All the isomers (A to G) showed a marked drop in Eg values. It is noticed that the Eg value decreased up to 46% of the original value. The partial and total density of state graphs for all seven structures indicate the emergence of new HOMOs between the frontier molecular orbitals of h-SiC. The isomer A exhibits a significant increase in polarizability (α = 669 au) and hyperpolarizability (βo = 9.395×10−29 esu) values compared to pure h-SiC. Global reactivity descriptors (IP, EA, and S) and low excitation energies endorse the enhanced NLO response of Cu@h-SiC. The EDDM (Electron density difference map) analysis is performed to gain insight into the electronic density differences at the ground and excited levels. QTAIM analysis is used to investigate the type and nature of the interaction between the Cu-atom and the h-SiC. TD-DFT calculations predict the absorption spectra in the visible and near-IR regions. This study may help in the fabrication of h-SiC-based materials with optimised NLO response.

Formation of Silicon Carbide Nanoclusters in the Process of Methyltrichlorosilane Oligomerization

Formation of Silicon Carbide Nanoclusters in the Process of Methyltrichlorosilane Oligomerization

Three-dimensional self-supporting superstructured double-sided nanoneedles arrays of iron carbide nanoclusters embedded in manganese, nitrogen co-doped carbon for highly efficient oxygen reduction reaction

Nitrogen- and transition metal-dual doped carbon materials with low cost and high catalytic performances are considered as one of promising alternatives for noble metal catalysts in acceleration of oxygen reduction reaction (ORR). In this work, three-dimensional (3D) self-supporting superstructures of iron carbide (Fe3C) nanoclusters entrapped in manganese (Mn)- and nitrogen (N)-dual doped carbon nanosheets covered with double-sided nanoneedles carbon arrays (Fe3C/Mn,N-NCAs) are simply synthesized by a coordination pyrolysis method, in which dicyandiamide mainly behaves as nitrogen source and 1-(2-pyridylazo)-2-naphthol (PAN) as carbon source. Integration of the unique 3D self-supporting superstructures and synergistic effects of the multi-compositions, the as-obtained catalyst displays appealing ORR performance such as the much positive onset potential (Eonset = 0.98 V vs. RHE) and half-wave potential (E1/2 = 0.88 V vs. RHE), as well as a just 10 mV negative shift in E1/2 after 2000 cycles, surpassing commercial Pt/C. This work provides some valuable perspectives for preparation of high-efficiency and low-cost non-noble metal ORR electrocatalysts in energy transformation and storage correlated systems.

Polymeric tungsten carbide nanoclusters as potential non-noble metal catalysts for CO oxidation.

The discovery of tungsten carbide (WC) as an analog of the noble metal Pt atom is of great significance toward designing novel highly-active catalysts from the viewpoint of the superatom concept. The potential of such a superatom to serve as building blocks of replacement catalysts for Pt has been evaluated in this work. The electronic properties, adsorption behaviors, and catalytic mechanisms towards the CO oxidation of (WC)n and Ptn (n = 1, 2, 4, and 6) were compared. Counterintuitively, these studied (WC)n clusters exhibit quite different electronic properties and adsorption behaviours from the corresponding Ptn species. For instance, (WC)n preferentially adsorbs O2, whereas Ptn tends to first combine with CO. Even so, it is interesting to find that the catalytic performances of (WC)n are always superior to the corresponding Ptn, and especially, the largest (WC)6 cluster exhibits the best catalytic ability towards CO oxidation. Therefore, assembling superatomic WC clusters into larger polymeric clusters can be regarded as a novel strategy to develop efficient superatom-assembled catalysts for CO oxidation. It is highly expected to see the realization of non-noble metal catalysts for various reactions in the near future experiments by using superatoms as building blocks.

Unravelling the reactivity of metastable molybdenum carbide nanoclusters in the C-H bond activation of methane, ethane and ethylene.

C-H bond activation steps in non-oxidative methane dehydroaromatization (MDA), constitute a key functionalization of the reactant and adsorbed species to form aromatics. Previous studies have focused on studying the energetics of these steps at the most stable active sites involving molybdenum carbide species. Herein, a different paradigm is presented via studying the reactivity of a metastable molybdenum carbide (Mo2C6) nanocluster for the C-H bond activation of methane, ethane, and ethylene and comparing it with the reactivity of the lowest energy Mo2C6 nanocluster. Interestingly, the metastable nanocluster is observed to result in a consistent reduction (by half) in the C-H bond activation barrier of the respective alkane and alkene molecules compared to the global minimum isomer. This specific metastable form of the nanocluster is identified from a cascade genetic algorithm search, which facilitated a rigorous scan of the potential energy surface. We attribute this significant lowering of the C-H bond activation barrier to unique co-planar orbital overlap between the reactant molecule and active centers on the metastable nanocluster. Based on geometrical and orbital analysis of the transition states arising during the C-H bond activation of methane, ethane, and ethylene, a proton-coupled electron transfer mechanism is proposed that facilitated C-H bond cleavage. Motivated by the high reactivity for C-H bond activation observed on the metastable species, a contrasting framework to analyze the elementary-step rate contributions is presented. This is based on the statistical ensemble analysis of nanocluster isomers, where the calculated rates on respective isomers are normalized with respect to the Boltzmann probability distribution. From this framework, the metastable isomer is observed to provide significant contributions to the ensemble average representations of the rate constants calculated for C-H bond activation during the MDA reaction.

Selective Adsorption Function of B16C16 Nano-Cage for H2O, CO, CH4 and NO2

The interactions between boron carbide (BC) nanocluster of B16C16 and H2O, NO2, CO, and CH4 small molecules were investigated by using density functional theory (DFT) computations to exploit the structural and electronic properties of the adsorbate/cluster complexes. The calculated adsorption energies of the most stable states are -16.6, -0.17, -1.28, -0.18 eV for NO2, CO, H2O, and CH4 molecules, respectively. Meanwhile, the interactions between CO and CH4 molecules and the cluster induce dramatic changes to the cluster electronic properties so that the molecular orbital (HOMO/LUMO) gap of cluster decreased its original value. It was shown that the phenomenon leads to an increment in the electrical conductivity of the cluster at a definite temperature. Furthermore, it is revealed that the adsorptions of NO2 and H2O molecules have no significant effects on the electronic properties of the cluster. Thus, this work suggests that the investigated B16C16 nano-cage could work as a selective gas sensor device towards CO, CH4, NO2 and H2O molecules.

Ferroferric oxide nanoclusters decorated Ti3C2Tx nanosheets as high performance anode materials for lithium ion batteries

Titanium carbide MXene as a new 2D anode material has been used for lithium ion batteries, due to its high electrical conductivity, low Li+ diffusion barriers and excellent chemical stability. Nevertheless, the low specific capacity of titanium carbide limits its application. Herein, we used facile ultrasonic and freeze drying methods to fabricate the ferroferric oxide (Fe3O4) modified Ti3C2Tx hybrids for lithium storage. In the hybrid, Fe3O4 nanoclusters are homogeneously anchored on the surface of the single or few layered Ti3C2Tx nanosheets by electrostatic interactions. Due to the synergistic effect of Fe3O4 nanoclusters and Ti3C2Tx nanosheets, all the prepared hybrids show superior lithium storage performance to the single titanium carbide and Fe3O4 nanoclusters. The hybrid with weight ratio of Ti3C2Tx nanosheets and Fe3O4 (1:1) exhibits a high lithium storage capacity of 437.6 mA h g−1 after 100 cycles at 100 mA g−1. Even at a high current density of 2 A g−1, it still retains a stable capacity of 326.6 mA h g−1 after 1000 long cycles. The excellent lithium storage performance is proved to be the combination of battery and capacitance behaviors based on the kinetics analysis. This work demonstrates that Fe3O4 nanoclusters decorated Ti3C2Tx nanosheets hybrids are promising high performance anode materials for lithium ion batteries.

Structure, wear and corrosion behaviours of Cr–Al–C and multilayer [Cr–Al–C/a-C]n coatings fabricated by physical vapour deposition and plasma-assisted chemical vapour deposition techniques

The structures, wear resistances, and corrosion behaviours of Cr–Al–C and multilayer [Cr–Al–C/a-C]n coatings, fabricated by physical vapour deposition (PVD), plasma-assisted chemical vapour deposition (PACVD), or their combination, were studied. A CrAl target served as a source of chromium and aluminium, while a graphite target or acetylene served as sources of carbon. Depending on the type of carbon source, Cr–Al–C or Cr–Al–C(H) coatings were obtained. Multilayer [Cr–Al–C/a-C]20 and [Cr–Al–C(H)/a-C:H]20 coatings were fabricated by alternating pair layers of [Cr–Al–C (PVD)/a-C (PVD)] and [Cr–Al–C(H) (PVD–PACVD)/a-C:H (PACVD)], respectively. a-C and a-C:H are hydrogen-free and hydrogenated diamond-like carbons. X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy were employed to investigate the coating structures. Along with the amorphous matrix, chromium carbide, and CrxAl1-xC nanograins, clusters of nanocrystalline graphite as spherical inclusions and plates, probably of several graphene layers, were observed in Cr–Al–C. This structure provided high hardness and corrosion resistance. Along with the amorphous matrix, Cr2AlC and chromium carbide nanoclusters and clusters of nanoscale CVD diamond with wide boundaries of sp2-bonded carbon were observed in Cr–Al–C(H), whose hardness did not exceed 8.9 GPa. The multilayer structures significantly increased the wear resistances. The specific coefficient of wear rate (SCWR) of [Cr–Al–C/a-C]20 was five times lower than that of Cr–Al–C. Hybrid PVD–PACVD technology provided favourable conditions for the formation of wear-resistant coatings. The SCWR of [Cr–Al–C(H)/a-C:H]20 was 47 times lower than that of [Cr–Al–C/a-C]20. The high wear resistance of the multilayer coatings was associated with the structure, low friction coefficient, high crack resistance, and strengthened interface boundaries.

Graphene Supported Tungsten Carbide as Catalyst for Electrochemical Reduction of CO2

Electrochemical reduction of CO2 to useful chemical and fuels in an energy efficient way is currently an expensive and inefficient process. Recently, low-cost transition metal-carbides (TMCs) have been proven to exhibit similar electronic structure similarities to Platinum-Group-Metal (PGM) catalysts and hence, can be good substitutes for some important reduction reactions. In this work, we test graphene-supported WC (Tungsten Carbide) nanoclusters as an electrocatalyst for the CO2 reduction reaction. Specifically, we perform density functional theory (DFT) studies to understand various possible reaction mechanisms and determine the lowest thermodynamic energy landscape of CO2 reduction to various products, such as CO, HCOOH, CH3OH, and CH4. This in-depth study of reaction energetics could lead to improvements and development of more efficient electrocatalysts for CO2 reduction.

Co-, Fe-, and N-Modified Carbon Composites for Excellent Catalytic Performances toward Electrochemical Reduction Reaction

The development of highly active noble-metal-free nitrogen-doped carbon materials is of great significance to the industrial applications of renewable and sustainable energy. In this paper, core-shell structural carbon materials composed of nitrogen-doped carbon-shell-encapsulated iron–cobalt mixed metal carbides were obtained through pyrolysis of metal organic framework precursors. Metallic (Co, Fe) carbide nanoclusters embedded in nitrogen-doped hollow carbon spheres were obtained after most of the mixed metal cores were removed by heated acid etching. The composites of carbon materials exhibited significant electrocatalytic activities toward the hydrogen evolution and oxygen reduction reactions. Hollow carbon spheres were obtained under optimized conditions for the hydrogen evolution reaction with overpotentials of 180 mV at a current density of 10 mA·cm–2 and Tafel slope of 90 mV·dec–1 in acidic media. The hollow carbon spheres also exhibited favorable activities toward oxygen reduction with a rather ...

Molecular-dynamic investigation of the influence of initial temperature on the character of shock-wave processes in silicon carbide nanocluster

In the present study, using the molecular dynamics method, we investigated the impact interaction of a spherical cluster of 3C-SiC silicon carbide with a rigid wall at a wide range of velocities. The influence of cluster initial temperature on the fracture process was analyzed.

Strongly Coupled Carbon Nanosheets/Molybdenum Carbide Nanocluster Hollow Nanospheres for High-Performance Aprotic Li-O2 Battery.

A highly efficient oxygen electrode is indispensable for achieving high-performance aprotic lithium-O2 batteries. Herein, it is demonstrated that strongly coupled carbon nanosheets/molybdenum carbide (α-MoC1-x ) nanocluster hierarchical hybrid hollow spheres (denoted as MoC1-x /HSC) can work well as cathode for boosting the performance of lithium-O2 batteries. The important feature of MoC1-x /HSC is that the α-MoC1-x nanoclusters, uniformly incorporated into carbon nanosheets, can not only effectively prevent the nanoclusters from agglomeration, but also help enhance the interaction between the nanoclusters and the conductive substrate during the charge and discharge process. As a consequence, the MoC1-x /HSC shows significantly improved electrocatalytic performance in an aprotic Li-O2 battery with greatly reduced charge and discharge overpotentials and long cycle stability. The ex situ scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy studies reveal that the mechanism for the high-performance Li-O2 battery using MoC1-x /HSC as cathode is that the incorporated molybdenum carbide nanoclusters can make oxygen reduction on their surfaces easy, and finally form amorphous film-like Li-deficient Li2 O2 with the ability to decompose at a low potential. To the best of knowledge, the MoC1-x /HSC of this paper is among the best cathode materials for lithium-O2 batteries reported to date.

Encapsulation of Molybdenum Carbide Nanoclusters inside Zeolite Micropores Enables Synergistic Bifunctional Catalysis for Anisole Hydrodeoxygenation

Molybdenum carbide (MoCx) nanoclusters were encapsulated inside the micropores of aluminosilicate FAU zeolites to generate highly active and selective bifunctional catalyst for the hydrodeoxygenation of anisole. Interatomic correlations obtained with differential pair distribution function analysis confirmed the intraparticle structure and the uniform size of the MoCx nanoclusters. The reactivity data showed the preferential production of alkylated aromatics (such as toluene and xylene) over benzene during the hydrodeoxygenation of anisole as well as the minimization of unwanted CH4 formation. Control experiments demonstrated the importance of MoCx encapsulation to generate an efficient bifunctional catalyst with superior carbon utilization and on-stream stability.

Boron carbide nanoclusters as H2 and N2 gases nanosensors: theoretical investigation

Interactions between boron carbide nanoclusters (B16C16 and B24C24) and H2 and N2 molecules have been investigated using the structural and electronic properties of the adsorbate/cluster complexes derived from density functional theory. The adsorption energies of the most stable configurations have been calculated to be about −0.13, −0.66 eV for H2 and N2 adsorbed on the B16C16 surface and −1.05, −3.80 eV for H2 and N2 adsorbed on the B24C24 surface, respectively. Moreover, the interaction between H2 and the B16C16 has induced dramatic changes to the cluster electronic properties, so that the HOMO/LUMO gap of the cluster decreases to its original value. It has been shown that this phenomenon has led to an increment in the electrical conductivity of the cluster at a definite temperature. Thus, this work suggests that the B16C16 and B24C24 nano-cages function selectively as a gas sensor device for H2 and N2 molecules.

Structural, electronic and vibrational properties of GexCy (x+y=2–5) nanoclusters: A B3LYP-DFT study

An ab-initio study of the stability, structural and electronic properties has been made for 84 germanium carbide nanoclusters, GexCy (x+y=2–5). The configuration possessing the maximum value of final binding energy (FBE), among the various configurations corresponding to a fixed x+y=n value, is named as the most stable structure. The vibrational and optical properties have been investigated only for the most stable structures. A B3LYP-DFT/6-311G(3df) method has been employed to optimize fully the geometries of the nanoclusters. The binding energies (BE), highest-occupied and lowest-unoccupied molecular orbital (HOMO–LUMO) gaps have been obtained for all the clusters and the bond lengths have been reported for the most stable clusters. We have considered the zero point energy (ZPE) corrections. The adiabatic and vertical ionization potentials (IPs) and electron affinities (EAs), charge on atoms, dipole moments, vibrational frequencies, infrared intensities (IR Int.), relative infrared intensities (Rel. IR Int.) and Raman scattering activities have also been investigated for the most stable structures. The configurations containing the carbon atoms in majority are seen to be the most stable structures. The strong C–C bond has important role in stabilizing the clusters. For the clusters containing one germanium atom and all the other as carbon atoms, the BE increases monotonically with the number of the carbon atoms. The HOMO–LUMO gap, IPs and EAs fluctuates with increase in the number of atoms. The nanoclusters containing even number of carbon atoms have large HOMO–LUMO gaps and IPs, whereas the nanoclusters containing even number of carbon atoms have small EAs. In general, the adiabatic IP (EA) is smaller (greater) than the vertical IP (EA). The optical absorption spectrum or electron energy loss spectrum (EELS) is unique for every cluster, and may be used to characterize a specific cluster. All the predicted physical quantities are in good agreement with the experimental data wherever available. The growth of these most stable structures should be possible in the experiments.