Χ3 Borophene Research Articles

Biaxial strain modulation of NO2 adsorption on χ3 borophene: A first-principles study

Based on first-principles calculations, the effects of applying biaxial strain to χ3 borophene and the adsorption behavior of NO2 molecule on the surface of χ3 borophene under strain are investigated. Firstly, the pristine borophene exhibits a metallic electronic structure and the thermodynamic stability of χ3 borophene is demonstrated by molecular dynamics simulations. Different adsorption sites and orientations are selected on the χ3 surface, and the optimal adsorption is found to be the S2 conformation, which has an adsorption energy of −1.589 eV. The applied biaxial strain significantly alters the electron density distribution of the χ3 borophene surface, which is predicted to be able to achieve a modification of the adsorption properties for NO2. Finally, we investigate the NO2 adsorption behavior of χ3 borophene surfaces under 1% to 5% biaxial tensile and compressive strains. Biaxial strain is found to enhance the NO2 adsorption capacity of the χ3 borophene surface, and χ3 at 3% biaxial tensile strain has the highest adsorption energy. Therefore, these results show that χ3 borophene can be a candidate material for gas sensors and theoretically guide researchers to develop more effective sensor materials for gas sensing.

Chiral Induction in 2D Borophene Nanoplatelets through Stereoselective Boron-Sulfur Conjugation.

Chirality is a structural metric that connects biological and abiological forms of matter. Although much progress has been made in understanding the chemistry and physics of chiral inorganic nanoparticles over the past decade, almost nothing is known about chiral two-dimensional (2D) borophene nanoplatelets and their influence on complex biological networks. Borophene's polymorphic nature, derived from the bonding configurations among boron atoms, distinguishes it from other 2D materials and allows for further customization of its material properties. In this study, we describe a synthetic methodology for producing chiral 2D borophene nanoplatelets applicable to a variety of structural polymorphs. Using this methodology, we demonstrate feasibility of top-down synthesis of chiral χ3 and β12 phases of borophene nanoplatelets via interaction with chiral amino acids. The chiral nanoplatelets were physicochemically characterized extensively by various techniques. Results indicated that the thiol presenting amino acids, i.e., cysteine, coordinates with borophene in a site-selective manner, depending on its handedness through boron-sulfur conjugation. The observation has been validated by circular dichroism, X-ray photoelectron spectroscopy, and 11B NMR studies. To understand how chiral nanoplatelets interact with biological systems, mammalian cell lines were exposed to them. Results showed that the achiral as well as the left- and right-handed biomimetic χ3 and β12 borophene nanoplatelets have distinct interaction with the cellular membrane, and their internalization pathway differs with their chirality. By engineering optical, physical, and chemical properties, these chiral 2D nanomaterials could be applied successfully to tuning complex biological events and find applications in photonics, sensing, catalysis, and biomedicine.

Investigating the effectiveness of borophene on anchoring and influence on kinetics of sodium superoxide in sodium–oxygen batteries

Owing to the increasing cost and limited resources of lithium metal, there is a growing interest in developing energy storage systems that are more affordable, environmentally friendly, and have high energy densities. This is also driven by the need to significantly reduce carbon dioxide emissions resulting from the use of fossil fuels. The sodium–oxygen battery has emerged as a potential alternative, as the materials used for both of its electrodes are among the most abundant and inexpensive elements on Earth. However, despite these advantages, there are technical challenges in implementing it, such as the insulation of the cathode electrode and failure to prevent discharge products from desorbing into electrolytes during discharging. In this study, using density functional theory based on first principles, we investigated the electronic properties of free-standing β12 and χ3-borophenes after adsorption of sodium superoxide (NaO2). Our findings showed that the adsorption energy of sodium superoxide on β12 and χ3 borophene are −3.85 eV and −3.24 eV, respectively. The large negative values of adsorption energy suggest that sodium superoxide is anchored spontaneously, which is significant as it can be prevented from migrating to the negative electrode via the electrolyte during the discharging process. Furthermore, the β12 and χ3 structures showed moderate diffusion energy barriers of 0.89 eV and 1.37 eV and decomposition energies of 0.73 eV and 0.52 eV, respectively. The latter demonstrates the catalytic effects of nanosheets on the decomposition of the sodium superoxide into separated sodium (Na+) and oxygen (O2). Moreover, the decomposition energies being lower than sodium superoxide formation energy (3.90 eV) in a vacuum, suggests nanosheets effects during the charging process. Most importantly, the metallic characteristics of both crystal structures were preserved after the adsorption of sodium superoxide, and the electronic conductivities were enhanced. This is significant to improve the cycle life of the battery, as the materials can charge back the decomposed species during the charging process, thereby preventing the formation of dendrites at the surface of the cathode. Ultimately, the predicted electronic properties for both structures demonstrate their potential as cathode electrode materials for enhancing the electrochemical processes of sodium–oxygen batteries.

Unveiling siliborophene's potential as an anode material for advancing Li ion batteries: DFT and ab-initio molecular dynamics

A favorable anodic candidate with significant potential is currently in high demand for Lithium-ion batteries. The χ3 borophene, a two-dimensional material, shows potential as an anode in Li-ion batteries. However, its original structure requires improvement to enhance its Li diffusivity and specific capacity. This research investigates the modification of χ3 borophene by silicon atoms, resulting in a new structure called siliborophene, using density functional theory. Ab-initio molecular dynamics simulations confirm the stability of siliborophene structure at room temperature. The Siχ3 structure hosts adsorption sites for the Li atom, and after exploring various positions, the most favorable configuration exhibits an adsorption energy of −1.33 eV. The siliborophene surface can adsorbed up to 13 Li atoms but according to the further analyses the results of open-circuit voltage suggest that the siliborophene structure can store 10 Li atoms, so Li10Siχ3 structure is considered as the structure with maximum adsorption capacity. The interaction between the surface and Li atoms is stronger in this configuration, with −1.10 eV adsorption energy which yields a maximum specific capacity of 1291 mAh/g. Analysis of the partial density of states and band structure reveals metallic characteristics of the surface during lithiation. Furthermore, using the CI-NEB approach, the barrier activation energy for Li diffusion was calculated, showing exceptionally low values at 0.32 eV, enabling rapid Li diffusion on the surface. These findings indicate that siliborophene holds promise as a potential anode material for lithium-ion batteries.

Production Methods and Energy Applications of Borophene

Two dimensional materials have unique physical, chemical and electrical properties. Many theoretical studies on borophene revealed important possible properties, such as metallicity, transparency, conductivity and chemical activity; due to vacancies present in its structure. It was first synthesized in 2015 and experimental studies on this new exciting 2D material is few in number. It was found that many of these studies still focus on expensive and sophisticated production methods such as Molecular Beam Epitaxy (MBE) and Chemical Vapor Deposition (CVD). Although graphene, first of these 2D materials, is being studied more than two decades, it could not do the expected impact on energy industry due to lack of production methods in industrial scale. In this review, it was intended to build a narrative on the experimental production methods and resulting structures of borophene rather than theoretical background. It was found that liquid phase exfoliation method to synthesize borophene sheets might be the most promising method to upscale borophene production. Theoretical, computational and experimental studies suggested that β12 and χ3 borophene structures were stable and could be produced by sonochemical exfoliation method. In addition, possible uses in energy applications and some future prospects were also discussed. Borophene produced this way, might be used in batteries, supercapacitors hydrogen evolution (HER) and oxygen evolution (OER) reactions.

DFT-Based Tight-binding model of vdW bilayer χ3 and β12 borophene

In this work, a tight-binding (TB) model with the Slater–Koster (SK) approximation is presented to describe the electronic properties of vdW bilayer χ3 and β12 borophene with AA stack. This model is created by using four orbitals of S, Px, Py, and Pz for each boron atom. By fitting the results of the TB model and density functional theory (DFT) calculations using the least-squares method and the Levenberg-Marquardt nonlinear fitting algorithm, the optimal Hamiltonian and the overlap matrix are calculated. This TB model well describes energy bands around high-symmetry k-points, by considering three nearest neighbors in each layer and a non-orthogonal basis set.

Achieving arbitrary CO2 adsorption energy on χ3 borophene surface by applying electric field or strain: DFT and RSM approaches

The study of χ3 borophene modification was considered finding an applicable technique to achieve more efficient approaches in CO2 capturing. In the framework of density functional theory (DFT), two surface modification methods were described, external electric field or strain application on χ3 borophene, and the effect of them was investigated on CO2 adsorption. All these methods affected the deformation charge density of the surface, which led to an increase in the CO2 binding energy, in the studied range. The turning point in CO2 capturing and structural changes appeared by applying an electric field of −0.030 a.u. strength with −0.48 eV adsorption energy. The uniaxial and biaxial compressive strain resulted in proper adsorption energy of −0.73 to −0.85 eV, although it caused a significant change in the planar structure of the surface. The structural and electronic properties, in addition to the charge density difference analysis, confirmed the chemisorption of CO2 on modified surfaces. Lastly, for the first time, the response surface methodology in the DFT framework was used to evaluate the simultaneous effect of applying an external electric field and strain as well as charge injection on CO2 adsorption. The generated quadratic equation predicts the CO2 adsorption energy with high accuracy as a function of the modification parameters. This result would be very helpful in adjusting the modification parameters to achieve the desired CO2 adsorption energy with lower experimental costs, where the χ3 surface is used for a special application such as CO2 removal or sensing.

Prediction of gas adsorption on [formula omitted] borophene: A density functional theory study

In this work, we present the electronic transport properties of χ3 borophene nanosheets in the presence of the CO, CO2, NO, NH3 gas molecules. Adsorption energy, adsorption distance, charge transfer, recovery time, the density of states, the current–voltage, the relative current change, the transmission spectrum and the STM image of the structures have been focused. The gas sensor capability of two-dimensional χ3 borophene nanosheet is investigated by calculation of the quantum transport in the framework of the nonequilibrium Green’s function formalism within the density functional theory. The results explore that χ3 borophene nanosheets are sensitive toward the NO and the NH3 gas adsorbates to the CO and CO2 ones.

Computational screening of χ3 borophene based single-atom catalysts for N2 reduction

Under ambient conditions, nitrogen reduction to ammonia through electrochemical reactions could be a promising strategy to circumvent the energy and capital-intensive commercial Haber−Bosch (HB) process. But developing suitable catalysts to compete with the similar reaction rate of the commercial HB process is the main bottleneck. In this paper, 3d, 4d, and 5d transition metals anchored on χ3 borophene have been considered as single-atom catalysts for ammonia synthesis. Comprehensive computational screening and systematic evaluation have been carried out to understand the catalytic activity and selectivity of these catalysts through two different reaction pathways: distal and alter. Fe and Mn-based SAC has the lowest overpotential (0.64 V and 0.79 V) in the distal and alter process, respectively. These catalysts also has depicted better selectivity to NRR compared to HER.

Investigation on electrochemical performance of striped, β12 and χ3 Borophene as anode materials for lithium-ion batteries

By developing next-generation lithium-ion batteries (LIBS), demand for exploring novel anode materials with exclusive electrochemical features and ultra-high capacity is increasing. In the current research, first-principles theory, and density functional theory (DFT) calculations were conducted to extensively investigate and compare the capability of three different borophene nanolayers, including striped, β12, and χ3 borophene, as a novel candidate for anode electrode in LIBs. We first predicted the most preferential Li atom adsorption sites on the three borophene structures. The predicted average formation energies for striped, β12, and χ3 borophene were obtained 3.123, 3.184, and 3.216 eV, respectively. The positive value of formation energy exhibits the sufficient stability of the structures. Moreover, the negative adsorption energy proved that Li atom insertion on all borophene monolayers is thermodynamically favorable. In order to simulate the lithiation process, we gradually increased the concentration of Li atoms. We found that the fully lithiated striped, β12 and χ3 borophenes could provide ultra-high specific capacities of 1700, 1983, and 1859 mAh/g, respectively. Structural analysis proved that the surface area expansion rate of the striped borophene in a fully lithiated state was 1%, which was lower than those of β12 and χ3 borophene with 3.33% and 2.63%, respectively. The analyses of electronic properties confirmed that borophenes were inherently metallic and superior ion conductive agents, even after fully lithiated state. Ion diffusion was studied using Nudged elastic band method and the value of diffusion energy barrier ranged from 0.03 to 0.36 eV which was lower than other promising 2D anode materials. Furthermore, open-circuit voltage results demonstrated that the electronic potential of modeled borophenes was low enough to be in the acceptable range of under 1.2V. All these reports exhibited that borophene nanolayers with excellent specific capacity and superior conductivity were desired candidates for anode materials of next generation LIBs.

Defect-induced magnetism in χ3 borophene

Defect-induced magnetism in χ3 borophene

Gas sensing behavior and adsorption mechanism on χ3 borophene surface

Following the demands to find high sensitivity sensors for pollutant gases with compact size, we investigate the adsorption mechanism and detecting capability of χ3 borophene, based on the density functional theory (DFT) calculations. Except for HCN, the overall structure of adsorbed molecules is maintained during the adsorption on the χ3 borophene surface. The obtained adsorption energies vary from −0.20 to −2.45 eV. While the CO2 molecule has a weak interaction with the surface, other molecules, notably CO, NO, NO2, SO, SO2, and SO3 adsorb strongly to the surface. The minimum-energy path and energy barrier for dissociation of the HCN molecule on the surface were studied in detail through the CI-NEB method. Plots of charge density difference and electron localization function demonstrated the covalent character of the formed bonds between N or S-containing gases and the surface. Our investigations of surface and adsorbate band alignments clearly justify the amount of charge transfer in the gap between the Fermi level of χ3 borophene and the LUMO of gas molecules. Furthermore, the surface sensitivity to adsorption was confirmed by analyzing the changes in the transmission coefficient, calculated with the non-equilibrium Green’s function approach. In terms of recovery time, SO, SO3, and NO2 molecules diminish the surface sensing performance, but the χ3 borophene surface is suitable for their removal from the environment. Accordingly, the thermal stability and adsorption capacity of these gases was investigated by Car-Parrinello molecular dynamics simulations. Our study not only clarifies the mechanism of the adsorption of various gas molecules on the χ3 borophene surface, but also reveals the benefit of χ3 in the sensing and removal of these gas species.

Performance improvement of χ3 borophene in nitrogen fixation using single–atom anchoring: A first–principles study

Under ambient conditions, reducing nitrogen to ammonia through electrochemical reactions is a promising strategy, which can decrease energy consumption and environmental pollution. Based on the density functional theory, we investigate the catalytic behavior of various transition metal atoms anchored on χ3 borophene (χ3-B) for nitrogen reduction reaction (NRR). The results show that Ti supported on χ3-B (Ti@χ3-B) exhibits the superior catalytic performance, with a minimum onset potential of -0.21 V, which is much better than -0.98 V of Ru(0001) surface. In addition, the competitive hydrogen evolution reaction is well suppressed. Importantly, the substrate Ag(111) introduced during the synthesis of χ3-B could further promote the catalytic effect of Ti@χ3-B in NRR. Our results demonstrate that Ti@χ3-B is an efficient and green catalyst for nitrogen fixation.

Borophene-supported single transition metal atoms as potential oxygen evolution/reduction electrocatalysts: a density functional theory study.

Due to the maximal atom utilization, high activity, and selectivity, the two-dimensional (2D) matrix supported single-atom catalysts (SACs) have attracted substantial research interests. In this work, we carried out the theoretical study on the stability, activity for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), and its dependence on the electronic structure of transition metal (TM) anchored on two types of borophene (called β12 and χ3) by density functional theory (DFT) calculations. The results show that the early- and VIII-TM anchored β12 and χ3 borophenes are structurally and thermodynamically stable. The overpotentials of OER (ηOER) over the Ni supported on β12 and χ3 borophene SACs, designated as β12-Ni and χ3-Ni, are 0.38 and 0.35V, respectively. The ηORR of β12-Ni and χ3-Ni are estimated to be as low as 0.34 and 0.39V, respectively. The OER/ORR activity of the SACs can be well correlated with their electronic structures. The high ηOER values of early TM supported on borophene SACs correspond to high d-band center of TM. Both β12-Ni and χ3-Ni have a moderate d-band center. Since the overpotentials for OER and ORR on β12-Ni and χ3-Ni are comparable to those of Pt group metals and their oxides, β12-Ni and χ3-Ni can be considered as the promising bifunctional catalysts for OER and ORR.

Density functional theory investigation on selective adsorption of VOCs on borophene

In the field of volatile organic compounds (VOCs) pollution control, adsorption is one of the major control methods, and effective adsorbents are desired in this technology. In this work, the density functional theory (DFT) calculations are employed to investigate the adsorption of typical VOCs molecules on the two-dimensional material borophenes. The results demonstrate that both structure of χ3 and β12 borophene can chemically adsorb ethylene and formaldehyde with forming chemical bonds and releasing large energy. However, other VOCs, including ethane, methanol, formic acid, methyl chloride, benzene and toluene, are physically adsorbed with weak interaction. The analysis of density of states (DOS) reveals that the chemical adsorption changes the conductivity of borophenes, while the physical adsorption has no distinct effect on the conductivity. Therefore, both χ3 and β12 borophene are appropriate adsorbents for selective adsorption of ethylene and formaldehyde, and they also have potential in gas sensor applications due to the obvious conductivity change during the adsorption.

Detection of nucleobases on borophene nanosheet: A DFT investigation

In this paper, we present a computational study investigating the electronic properties of DNA nucleobases (Adenine, Guanine, Cytosine and Thymine) on χ3 borophene using a combination of density functional theory (DFT) and non-equilibrium Green’s function (NEGF) formalism.The adsorption energy, equilibrium distance, net charge of transfer, and density of states (DOSs) are obtained at different molecule orientations and selective positions.The most stable geometries of DNA molecules on χ3 borophene are also determined.By using (NEGF) formalism, the electronic transmission and electrical current are calculated separately as a function of applied bias voltage for each nucleobase. We find that attaching this molecule to borophene changes the electrical conductivity.Results indicate the strong potential of borophene in adsorption of the DNA molecules, meaning this two-dimensional material could be a suitable candidate for future DNA sequencing devices.

A thorough study on the F-decoration of χ3 borophene and enhancement of anodic performance of Lithium-ion batteries

χ3 borophene is a promising 2D anode material in Lithium-ion batteries, but its pristine structure needs to be improved for increasing its specific capacity and Li diffusivity. For this purpose, the decoration of χ3 with the Fluorine atom was investigated using the density functional theory. Two F-decorated χ3 configurations (Fχ3-A and Fχ3-B) with very close energy and good kinetic stability were identified for the Li storage. Li atoms were gradually loaded on both configurations and the results showed a maximum specific capacity of 1396 mAh/g for the Fχ3-B structure which thermodynamically is a slightly lower stable configuration. The interaction of the Li atom with the surface is stronger in this configuration and resulting in −1.75 eV adsorption energy. The PDOS and band structure analysis showed a good metallic characteristic of the surface during lithiation process. The Li diffusion barrier in this structure is extremely low, 0.21 eV, which enables very fast Li diffusion on the surface. Also, this study demonstrated the importance of considering the different configurations resulting from decorating a structure, with proper thermodynamic and kinetic stability, in the computational investigation. As in this study, for F-decorated χ3 borophene, the configuration with lower stability and symmetry showed better results in all storage parameters of Li atoms.

First-principles calculations on the intrinsic resistivity of borophene: anisotropy and temperature dependence

Temperature dependence and anisotropy of the intrinsic resistivity of β12 and χ3 borophene.

Tunable magnetic and electronic properties in 3d transition-metal adsorbed β12 and χ3 borophene

Recently, the experimental advances for the fabrication of various borophene sheets introduced novel lattice structures with a wide prospect of practical applications. Borophene with various structural polymorphs are metallic and nonmagnetic, which greatly limits its application in nanoelectronic and spintronic devices. Here, we predict that the 3d transition-metal adsorption is an effective approach to tailor the electronic structure of borophene by density functional theory. The Cr- and Mn-absorbed borophenes show magnetism, while non-magnetic states appear in Sc-, Ti-, V-, Fe-, Co-, Ni-, Cu- and Zn-adsorbed systems. Especially, Fe-adsorbed χ3 borophene is a non-magnetic semiconductor, whose gap opening and magnetic moment can be tailored by strain. Our work provides a clue for exploring the method to tailor the magnetic and electronic properties of two dimensional monolayer borophene.

The adsorption and dissociation of oxygen on Ag (111) supported χ3 borophene

The superstructure of χ3 borophene on Ag (111) has recently been synthesized in experiment. In this work, we investigate its structural, electronic properties and the oxidation mechanism through first-principles calculations. We find the superstructure of χ3 borophene on Ag (111) maintain the planar characteristics, like its free-standing form, owing to the weakly interaction between adsorbate and substrate. Moreover, oxygen molecule can be spontaneously adsorbed on its superstructure in a manner of chemical adsorption. Importantly, the energy barrier of ∼0.35 eV for oxygen dissociation indicates its relative stability in ambient conditions compared with the active silicene. Furthermore, the mobility of O2-dissociation-induced O atom is poor at room temperature, implying the difficult migration of O atom on borophene surface. On the other hand, due to the strong BO bonding, desorption of O2-dissociation-induced O atoms on superstructure of χ3 borophene becomes impossible, ultimately leading to form the boron oxides.