Borophene Sheets Research Articles

Stacked borophene-based electric double-layer supercapacitors

As an exceptional metallic Dirac material, borophene shows promise for superior mechanical and electronic properties, making it increasingly significant in electronics. Both theoretical predictions and experimental evidence underscore its potential in energy storage applications. However, due to existing limitations in synthesis techniques, the application of stacked borophene as flexible electrodes remains unexplored. This study aims to overcome these challenges by introducing an innovative in situ co-eutectic salt method for synthesizing AB-stacked hydrogenated borophene sheets. These sheets are then employed to fabricate large-scale electrodes and construct flexible electric double-layer supercapacitors based on borophene. The robust mechanical stability of stacked borophene facilitates significant improvements in interfacial characteristics and energy storage performance through rolling processes. This enhancement results in increased specific capacity, improved rate performance, and enhanced cyclic stability of thin-film electrodes. Specifically, the optimized borophene-based supercapacitor achieves a high specific areal capacitance of up to 417.3 mF/cm2 in an organic electrolyte at a current density of 1 mA/cm2, which represents a twofold improvement compared to non-stacked borophene structures. Remarkably, it retains over 88.3 % of this specific areal capacitance even at a high current density of 15 mA/cm2, demonstrating impressive rate capability. Furthermore, after 5000 charge–discharge cycles, the capacitance retention exceeds 89.3 %. This research is expected to catalyse the application and advancement of borophene in future flexible and portable electronic devices, highlighting its potential transformative impact in energy storage technologies.

High‐Entropy‐Stabilized Platinum Diborides for Poison‐Resistant Catalysis

AbstractAlloying and solid‐solution formation is a powerful technique that enhances and adds properties through elemental mixing, but unfortunately, some elements simply cannot mix as their chemical nature prevents a thermodynamically stable structure. For example, the inherent nobility of platinum group metals does not favor bond formation and precludes their incorporation into higher (boron‐rich) metal borides. However, we demonstrate that when using five or more constituents, the higher mixing entropy will overcome these chemical limitations and form a stable high‐entropy alloy, demonstrating the formation of new compounds with substituents that are seemingly impossible with a traditional metal alloying approach. The high‐entropy boride (HEB) Al0.2Nb0.2Pt0.2Ta0.2Ti0.2B2 was synthesized, where platinum was forced to occupy a 12‐coordinate site, sandwiched between honeycomb borophene sheets. In addition to the unusual coordination, the boron serves as a poison panacea. Pure platinum is strongly susceptible to sulfur poisoning by adsorption, rendering a platinum catalyst ineffective. Boron is known to be resistant to sulfur poisoning. The boron sheets present in the HEB shield the platinum from sulfur while maintaining high catalytic activity. This is confirmed with the facile hydrogenation of thiol‐containing nitro compounds, where the HEB resists sulfur poisoning while retaining its high catalytic activity.

Enhanced near-field radiative heat transfer between borophene sheets on different substrates

Abstract Near-field radiative heat transfer (NFRHT) has the potential to exceed the blackbody limit by several orders of magnitude, offering significant opportunities for energy harvesting. In this study, we have examined the NFRHT between two borophene sheets through the calculation of heat transfer coefficient (HTC). Due to the tunneling of evanescent waves, borophene sheet allows for enhanced heat flux and adjustable NFRHT by varying its electron density and electron relaxation time. Additionally, the near field coupling is further examined when the borophene is deposited on dielectric or lossy substrates. The maximum HTC is closely related to the real part of the dielectric substrate. As a case study, the HTC on the lossy substrate of MoO3, ZnSe and SiC are calculated for comparison. Our results indicate that MoO3 is the optimal substrate to get the enhanced energy transfer coefficient. It results in a remarkable value of 1737 times higher than the blackbody limit owing to the enhanced photon tunneling probability. Thus, our study reveals the effect of substrate on the HTC between borophene sheets and provides a theoretical guidance for the design of near-field thermal radiation devices.

Valency-based structural properties of gamma-sheet of boron clusters.

Boron cluster sheets are two-dimensional boron atom-based formations called borophene. They are similar to the two-dimensional sheet known as graphene, which is composed of carbon atoms arranged in a hexagonal lattice. The unique electrical, mechanical, and thermal properties of borophene make it a sought-after substance for a variety of uses, such as catalysis, energy storage, and electronics. There are two ways to manufacture borophene: chemical vapor deposition and molecular beam epitaxy. Vertex-edge valency-based topological descriptors are a great example of a molecular descriptor that provides information on the connection of atoms in a molecule. These descriptions are based on the notion that a node's value in a molecular network is the sum of the valency of those atoms that are directly connected to that node. In this article, we discussed some novel vertex-edge (ve) and edge-vertex (ev) topological descriptors and found their formulations for the boron cluster or borophene sheets. Also, we show the numerical and graphical comparison of these descriptors in this article.

Hummers' method-assisted liquid-phase exfoliation enables the fabrication of few-layer borophene from bulk boron.

The fabrication of few-layer borophene (BP) from bulk boron (b-B) is of great importance and still a scientific challenge due to the complex structure and crystallinity of b-B. Herein, we propose a novel technique to prepare a few-layer BP on a large scale with a large lateral size in a well-controlled manner. For this, we employed the Hummers' method-assisted liquid-phase exfoliation. In the first step, the chemical exfoliation of the b-B as a precursor was performed by the modified Hummers' method. After chemical exfoliation, mechanical delamination was employed by using an immersion sonicator. Finally, BP sheets were collected with dimensions ranging from several hundred nanometers to a few micrometers and an average thickness of 4.2 nm. We envision that the proposed low-cost, flexible, and large-scale production method will provide unique advantages for the application of few-layer BP in the realization of high-performance electronics, optoelectronics, flexible devices, sensing systems, energy conversion, and storage devices.

B63: The Most Stable Bilayer Structure with Dual Aromaticity.

The emergence of a bilayer B48 cluster, which has been both theoretically predicted and experimentally observed, as well as the recent experimental synthesis of bilayer borophene sheets on Ag and Cu surfaces, has generated tremendous curiosity in the bilayer structures of boron clusters. However, the connection between bilayer boron cluster and bilayer borophene remains unknown. By combining a genetic algorithm and density functional theory calculations, a global search for the low-energy structures of the B63 cluster was conducted, revealing that the Cs bilayer structure with three interlayer B-B bonds is the most stable bilayer structure. This structure was further examined in terms of its structural stability, chemical bonding, and aromaticity. Interestingly, the interlayer bonds induce strong electronegativity and robust aromaticity. Furthermore, the dual aromaticity stems from diatropic currents originating from virtual translational transitions for both σ and π electrons. This unprecedent bilayer boron cluster is anticipated to enrich the concept of dual aromaticity and serve as a potential precursor for bilayer borophene.

Borophene: a piezocatalyst for water remediation.

Borophene is an emerging two-dimensional material exhibiting exceptional piezocatalytic activity under the influence of ultrasonic vibrations, as exemplified herein by the decomposition of highly stable organic dyes in water. After 6 minutes of exposure, borophene sheets converted up to 92 percent of a mixture of dye molecules at room temperature.

Li-decorated bilayer borophene as a potential hydrogen storage material: A DFT study

Two-dimensional (2D) materials have recently attracted much attention in the field of hydrogen storage, owing to their beneficial properties such as high surface-to-volume ratio and light weight. Motivated by recent experimental developments of bilayer borophene (BL) sheets, we investigate the suitability of hydrogen storage on Li-decorated BL via density functional theory (DFT) calculations. The H2 molecules are adsorbed on BL sheet via weak physisorption. By decorating BL with Li atoms, its hydrogen storage performance has been improved. We find that Li atoms can firmly adsorb on the substrate without forming clusters. Meanwhile, the Li-decorated structure exhibits good stability, verified by molecular dynamics calculations. Remarkably, in the fully loaded case, the compound obtains a 6.08 wt% H2 content and 0.13 eV/H2 average adsorption energy, which is promising for onboard hydrogen storage. Furthermore, electronic structure analysis reveals the electrostatic nature of interactions between the H2 molecules and the protruding Li atoms on BL sheets, which originates from polarization and orbital hybridization. Overall, our results suggest that Li-decorated BL is a promising candidate for potential hydrogen storage applications, and contribute to a better understanding of bilayer materials for hydrogen storage.

Refined degree bond partitions, topological indices, graph entropies and machine-generated boron NMR spectral patterns of borophene nanoribbons

The advent of borophene sheets and their nanoribbons has inspired significant experimental and theoretical research on the 2D-sheets and nanoribbons of boron, wonder materials of the future with the potential to replace graphene. As a result of the electron deficient nature of boron compounds, borophenes exhibit multiple phases with contrasting network structures. The present study employs novel graph theoretical techniques based on neighborhood degree-sum parameters that provide refined bond partitions to characterize the different phases of borophene nanoribbons. We have applied these techniques to the β12 and χ3 phases of borophene nanoribbons. We have also employed computer-assisted combinatorial techniques to generate the boron NMR spectra of different phases of the borophene nanoribbons.

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.

Boron clusters sheets with algebraic properties

Boron clusters are small, three-dimensional structures made of boron atoms. These come in a wide range of shapes and sizes, from basic planar constructions to complex polyhedral patterns. Boron clusters are fascinating from both a fundamental and practical perspective because of their unique electrical, optical, and chemical properties. More focus has lately been placed on boron cluster sheets, which are two-dimensional structures made of boron clusters. Quantitative structure-activity relationship (QSAR) studies implement M-polynomials, a type of molecular descriptor, to describe the topology of molecules. These are based on the notion of graph theory, which provides a theoretical framework for quantitatively studying molecular graphs. In this article, we discussed some novel topological descriptors-based M-polynomials and found algebraic formulations for the boron cluster or borophene sheets. We discussed first Zagreb, second Zagreb and Randić M-polynomials, based on the different differential and integral operators.

Low-Pressure CVD Synthesis of Tetragonal Borophene Single-Crystalline Sheets with High Ambient Stability

Being a typical graphene-like two-dimensional (2D) material, borophene has received a lot of attention due to its low density, high electron mobility, large Young’s modulus, and good chemical stability. Compared with the corresponding bulk counterparts, 2D borophene has larger specific surface area, higher conductivity, and smaller work function, finding potential applications in high-speed transistors, optoelectronic detection, field emission (FE), and mechanical enforcement areas. In this paper, 2D tetragonal borophene sheets with high ambient stability have been successfully fabricated on the surface of 1 cm2 copper foil using a developed low-pressure chemical vapor deposition (LPCVD) method. The vapor–solid mechanism was used to comprehend the formation of the tetragonal borophene sheets. The electrical conductivity of individual borophene sheets ranged from 4 to 5 × 10–4 S/cm, and the band gap was about 2.1 eV, suggesting their narrow semiconductive nature. Also, the maximum FE current of individual borophene sheets was close to 1 μA, and their emission properties enhanced with the decreasing sheet thickness, comparable to many other nanomaterials with excellent FE performances. More interestingly, individual borophene sheets were found to retain good enough electrical transport and FE behaviors even if they experienced several days’ atmospheric conservations. Our research results suggest that the LPCVD-grown borophene may be a promising building block for constructing high-performance nanodevices with good ambient stability.

Nickel foam deposited with borophene sheets used as a self-supporting binder-free anode for lithium-ion batteries

Nickel foam-supported borophene sheets were prepared using an improved chemical vapor deposition process. The as-obtained borophene sheets have crystaline nature, where the β12phase is dominant and contributes to high capacity for lithium storage.

Single B-vacancy enriched α1-borophene sheet: an efficient metal-free electrocatalyst for CO2 reduction.

By employing first principles calculations, we have studied the electronic structures of pristine (α1) and different defective (α1-t1, α1-t2) borophene sheets to understand the efficacy of such systems as metal-free electrocatalysts for the CO2 reduction reaction. Among the three studied systems, only α1-t1, the defective borophene sheet created by removal of a 5-coordinated boron atom, can chemisorb and activate a CO2 molecule for its subsequent reduction processes, leading to different C1 chemicals, followed by selective conversion into C2 products by multiple proton coupled electron transfer steps. The computed onset potentials for the C1 chemicals such as CH3OH and CH4 are low enough. On the other hand, in the case of the C2 reduction process, the C-C coupling barrier is only 0.80 eV in the solvent phase which produces CH3CHO and CH3CH2OH with very low onset potential values of -0.21 and -0.24 V, respectively, suppressing the competing hydrogen evolution reaction.

Growing borophene on metal substrates: A theoretical study of the role of oxygen on Al(111)

Charge transfer from a metal substrate stabilizes honeycomb borophene, whose electron deficit would otherwise spoil the hexagonal order of a $\pi$-bonded 2D atomic network. However, the coupling between the substrate and the boron overlayer may result in the formation of strong chemical bonds that would compromise the electronic properties of the overlayer. In this paper we present a theoretical study, based on state-of-the-art density-functional and genetic-optimization techniques, of the electronic and structural properties of borophene grown on Al(111), with emphasis on the impact of oxygen on the strength of the coupling between substrate and overlayer. While our results confirm the formation of Al-B bonds, they also predict that oxygen doping reduces charge transfer between aluminum and borophene, thus allowing modulation of their strength and paving the way to engineering the electronic properties of 2D-supported borophene sheets for industrial applications. Our study is completed by a thorough study of the thermodynamic stability of the oxygenated borophene-Al(111) interface.

Adsorption Behavior of Toxic Carbon Dichalcogenides (CX2; X = O, S, or Se) on β12 Borophene and Pristine Graphene Sheets: A DFT Study.

The adsorption of toxic carbon dichalcogenides (CX2; X = O, S, or Se) on β12 borophene (β12) and pristine graphene (GN) sheets was comparatively investigated. Vertical and parallel configurations of CX2⋯β12/GN complexes were studied herein via density functional theory (DFT) calculations. Energetic quantities confirmed that the adsorption process in the case of the parallel configuration was more desirable than that in the vertical analog and showed values up to −10.96 kcal/mol. The strength of the CX2⋯β12/GN complexes decreased in the order CSe2 > CS2 > CO2, indicating that β12 and GN sheets showed significant selectivity for the CSe2 molecule with superb potentiality for β12 sheets. Bader charge transfer analysis revealed that the CO2⋯β12/GN complexes in the parallel configuration had the maximum negative charge transfer values, up to −0.0304 e, outlining the electron-donating character of CO2. The CS2 and CSe2 molecules frequently exhibited dual behavior as electron donors in the vertical configuration and acceptors in the parallel one. Band structure results addressed some differences observed for the electronic structures of the pure β12 and GN sheets after the adsorption process, especially in the parallel configuration compared with the vertical one. According to the results of the density of states, new peaks were observed after adsorbing CX2 molecules on the studied 2D sheets. These results form a fundamental basis for future studies pertaining to applications of β12 and GN sheets for detecting toxic carbon dichalcogenides.

Borophene reinforcing copper matrix composites: Preparation and mechanical properties

The excellent mechanical properties that combine strength, flexibility and toughness make borophene a highlighted material system for innovative applications of nanoelectronic devices and promising for reinforcing metal matrix composites. However, the experiments have not been reported so far due to the difficulty of macroscale preparation of borophene sheets. Recently, large-scale, free-standing, ultrastable hydrogenated borophene sheets have been synthesized in our group using an in-situ multi-step thermal decomposition method of sodium borohydride. Here, borophene reinforcing copper matrix composites were prepared by in-situ thermal decomposition of sodium borohydride powder in hydrogen rich environment. The corresponding bulk three-dimensional borophene sheets network/copper composites were prepared by spark plasma sintering. The structure of borophene in the samples before and after sintering is well consistent with that of triangular borophene. The mechanical properties of the composites are significantly improved by the introduction of borophene. The yield strength and ultimate tensile strength of the composites are close to the reported highest values of graphene in copper matrix and far beyond those of boron nitride in copper matrix. The change of fracture mode from ductile fracture to brittle fracture is ascribed to the stronger interfacial affinity between borophene and copper compared with that between graphene and copper. This study paves the way for the practical application of borophene in high-performance metal matrix composites.

Introduction and investigation of PbI2/NdI2/CuI and PbI2/G/NdI2/B/CuI multilayer for optoelectronic applications

In recent years, one of the main research fields is the introduction of compounds that can increase the efficiency of solar cells and improve the performance of photovoltaic devices. In this study, a novel combination of PbI2/NdI2/CuI from metal dichalcogenide was introduced and investigated with the aim of introducing a suitable structure for solar cells, sensors and optical devices. The PbI2/G/NdI2/B/CuI dichalcogenide was also investigated according to the properties of Graphene and Borophene. Structural properties, configuration, optical properties, including dielectric function, refractive index, reflectivity, extinction coefficient and electron energy loss spectroscopy (EELS) have been studied. Studies were performed based on density functional theory (DFT). The results showed that NdI2 changes the crystal structure of PbI2 and CuI. With Graphene and Borophene sheets, the configuration changes. The results showed that the compound PbI2/NdI2/CuI is an indirect-gap semiconductor with and is PbI2/G/NdI2/B/CuI a direct-gap semiconductor. The introduced compounds are useful for use in detectors and electron filtration due to the selection of selective transition of the electrons based on the energy (energy greater than 15 eV and around 7 eV especially). They also have promising prospects for improving the performance of solar cells and sensors due to the good absorption of light in the visible region.

Tunable narrow transparency windows induced by the coupled quasi-guided modes in borophene plasmonic nanostructure

A grating-assisted triple-layer continuous borophene sheets structure is presented to investigate the phase-coupled plasmon-induced transparency (PIT) effect at the near-infrared communication band. In the proposed structure, the diffraction grating is utilized to couple the normal incident waves, which excites the quasi-guided mode in triple-layer continuous borophene sheets. Compared to the patterned structure, the requirement of complicated processing techniques and extra doping configurations for tuning carrier density can be avoided by using the continuous borophene sheet. Additionally, the narrower transparency windows are shown in the spectral responses via the phase coupling between two detuned quasi-guided modes with high quality factors. The transparency windows can be efficiently tuned by adjusting the carrier densities in borophene sheets or the separation distances between the borophene sheets. The analytical results based on temporal coupled mode theory and transfer matrix method are consistent with the numerical simulations via finite-difference time-domain calculations. The proposed scheme provides the promising design of a tunable PIT component that is compatible with optical communication technology.

Macroscopic Single-Phase Monolayer Borophene on Arbitrary Substrates.

A major challenge in the investigation of all 2D materials is the development of synthesis protocols and tools which would enable their large-scale production and effective manipulation. The same holds for borophene, where experiments are still largely limited to in situ characterizations of small-area samples. In contrast, our work is based on millimeter-sized borophene sheets, synthesized on an Ir(111) surface in ultrahigh vacuum. Besides high-quality macroscopic synthesis, as confirmed by low-energy electron diffraction (LEED) and atomic force microscopy (AFM), we also demonstrate a successful transfer of borophene from Ir to a Si wafer via electrochemical delamination process. Comparative Raman spectroscopy, in combination with the density functional theory (DFT) calculations, proved that borophene's crystal structure has been preserved in the transfer. Our results demonstrate successful growth and manipulation of large-scale, single-layer borophene sheets with minor defects and ambient stability, thus expediting borophene implementation into more complex systems and devices.