Insights into the DHQ-BN: mechanical, electronic, and optical properties

Computational materials research is vital in improving our understanding of various class of materials and their properties, contributing valuable information that helps predict innovative structures and complement empirical investigations. In this context, DHQ-graphene recently emerged as a stable two-dimensional carbon allotrope composed of decagonal, hexagonal, and quadrilateral carbon rings. Here, we employ density functional theory calculations to investigate the mechanical, electronic, and optical features of its boron nitride counterpart (DHQ-BN). Our findings reveal an insulating band gap of 5.11 eV at the HSE06 level and good structural stability supported by phonon calculations and ab initio molecular dynamics simulations. Moreover, DHQ-BN exhibits strong ultraviolet (UV) activity, suggesting its potential as a highly efficient UV light absorber. Its mechanical properties, including Young's modulus (230 GPa) and Poisson's ratio (0.7), provide insight into its mechanical resilience and structural stability.

On the CO[Formula: see text] adsorption in a boron nitride analog for the recently synthesized biphenylene network: a DFT study

CONTEXT

Recent advances in nanomaterial synthesis and characterization have led to exploring novel 2D materials. The biphenylene network (BPN) is a notable achievement in current fabrication efforts. Numerical studies have indicated the stability of its boron nitride counterpart, known as BN-BPN. In this study, we employ computational simulations to investigate the electronic and structural properties of pristine and doped BN-BPN monolayers upon CO[Formula: see text] adsorption. Our findings demonstrate that pristine BN-BPN layers exhibit moderate adsorption energies for CO[Formula: see text] molecules, approximately [Formula: see text]0.16 eV, indicating physisorption. However, introducing one-atom doping with silver, germanium, nickel, palladium, platinum, or silicon significantly enhances CO[Formula: see text] adsorption, leading to adsorption energies ranging from [Formula: see text]0.13 to [Formula: see text]0.65 eV. This enhancement indicates the presence of both physisorption and chemisorption mechanisms. BN-BPN does not show precise CO[Formula: see text] sensing and selectivity. Furthermore, our investigation of the recovery time for adsorbed CO[Formula: see text] molecules suggests that the interaction between BN-BPN and CO[Formula: see text] cannot modify the electronic properties of BN-BPN before the CO[Formula: see text] molecules escape.

METHODS

We performed density functional theory (DFT) simulations using the DMol3 code in the Biovia Materials Studio software. We incorporated Van der Waals corrections (DFT-D) within the Grimme scheme for an accurate representation. The exchange and correlation functions were treated using the Perdew-Burke-Ernzerhof (PBE) functional within the generalized gradient approximation (GGA). We used a double-zeta plus polarization (DZP) basis set to describe the electronic structure. Additionally, we accounted for the basis set superposition error (BSSE) through the counterpoise method. We included semicore DFT pseudopotentials to accurately model the interactions between the nuclei and valence electrons.

On the mechanical, electronic, and optical properties of the boron nitride analog for the recently synthesized biphenylene network: a DFT study

CONTEXT

Recently, a new 2D carbon allotrope named biphenylene network (BPN) was experimentally realized. Here, we use density functional theory (DFT) calculations to study its boron nitride analogue sheet's structural, electronic, and optical properties (BN-BPN). Results suggest that BN-BPN has good structural and dynamic stabilities. It also has a direct bandgap of 4.5 eV and significant optical activity in the ultraviolet range. BN-BPN Young's modulus varies between 234.4[Formula: see text]273.2 GPa depending on the strain direction.

METHODS

Density functional theory (DFT) simulations for the electronic and optical properties of BN-BPN were performed using the CASTEP package within the Biovia Materials Studio software. The exchange and correlation functions are treated within the generalized gradient approximation (GGA) as parameterized by Perdew-Burke-Ernzerhof (PBE) and the hybrid functional Heyd-Scuseria-Ernzerhof (HSE06). For convenience, the mechanical properties were carried out using the DFT approach implemented in the SIESTA code, also within the scope of the GGA/PBE method. We used the double-zeta plus polarization (DZP) for the basis set in these cases. Moreover, the norm-conserving Troullier-Martins pseudopotential was employed to describe the core electrons.

Overlapping electron density and the global delocalization of π-aromatic fragments as the reason of conductivity of the biphenylene network

Recently fabricated 2D biphenylene network is an astonishing solid-state material, which possesses unique metal-like conductive properties. At the same time, two-dimensional boron nitride network (2D-BN)-an isoelectronic and structural analogue of biphenylene network, is an insulator with a wide direct bandgap. This study investigates the relationship between the electronic properties and chemical bonding patterns for these species. It is shown that the insulating 2D-BN network possesses a strong localization of electron density on the nitrogen atoms. In turn, for a carbon-containing sheet, we found a highly delocalized electron density and an appreciable overlap of p_z orbitals of neighboring C₆ rings, which might be a reason for the conductive properties of the material.

Low pressure metastable single-bonded solid nitrogen phases

Within the framework of the density functional theory, the possibility of the formation of single-bonded solid atomic nitrogen phases as a result of adiabatic compression of molecular and cluster nitrogen structures at zero temperature has been studied. It has been demonstrated that nitrogen clusters N₈(C_2v)-B, which are theoretically predicted as one of the promising candidates for high energy density materials, can transform under compression into a solid atomic phase with crystal lattice symmetry P2₁. The P2₁ phase is dynamically stable under decompression to zero pressure. It is shown that the ε-N₂ molecular phase transforms under compression into a solid atomic phase with R3̄c symmetry, and retains a vibrationally stable crystal structure when the pressure is reduced to 30 GPa, transforming into a stable cluster form at lower pressures. The atoms in the P2₁ and R3̄c solid atomic phases are linked by single bonds; therefore, these structures can store a large amount of energy ≈1.4 eV per atom. A detailed comparison of the properties of new P2₁ and R3̄c solid atomic phases with other nitrogen crystal structures that are dynamically stable at low pressures has been carried out.

A biphenylene nanoribbon-based 3D metallic and ductile carbon allotrope

Assembling two-dimensional (2D) sheets for three-dimensional (3D) functional materials is of current interest. Motivated by the recent experimental synthesis of 2D biphenylene [Science372 (2021) 852], we propose a new porous 3D metallic carbon structure, named T48-carbon, by using biphenylene nanoribbons as the building block. Based on state-of-the-art theoretical calculations, we find that T48-carbon is not only dynamically, thermally, and mechanically stable, but also energetically more favorable as compared with some other theoretically predicted carbon allotropes. Especially, T48-carbon exhibits mechanical anisotropy, ductility and intrinsic metallicity. A detailed analysis of electronic properties reveals that the metallicity mainly comes from the p_z-orbital of sp²-hybridized carbon atoms. This work shows the promise of design and synthesis of 3D biphenylene-based metallic carbon materials with novel properties.

Structure, stability and electronic properties of one-dimensional tetrathia- and tetraselena[8]circulene-based materials: a comparative DFT study

Computations reveal how the electronic and optical properties can be controlled in nanostructures.

Hydrogenation and Fluorination of 2D Boron Phosphide and Boron Arsenide: A Density Functional Theory Investigation

First-principles density functional theory calculations are performed to study the stability and electronic properties of hydrogenated and fluorinated two-dimensional sp³ boron phosphide (BP) and boron arsenide (BAs). As expected, the phonon dispersion spectrum and phonon density of states of hydrogenated and fluorinated BX (X = P, As) systems are found to be different, which can be attributed to the different masses of hydrogen and fluorine. Hydrogenated BX systems bear larger and indirect band gaps and are found to be different from fluorinated BX systems. These derivatives can be utilized in hydrogen storage applications and ultrafast electronic devices. Finally, we investigated the stability and electronic properties of stacked bilayers of functionalized BP. Interestingly, we found that these systems display strong interlayer interactions, which impart strong stability. In contrast with the electronic properties determined for the fluorinated/hydrogenated monolayers, we found that the electronic properties of these bilayers can finely be tuned to a narrow gap semiconductor, metallic or nearly semimetallic one by selecting a suitable arrangement of layers. Moreover, the nearly linear dispersion of the conduction band edge and the heavy-, light-hole bands are the interesting characteristics. Furthermore, the exceptional values of effective masses assure the fast electronic transport, making this material very attractive to construct electronic devices.

Super high-energy density single-bonded trigonal nitrogen allotrope—a chemical twin of the cubic gauche form of nitrogen

A new ambient-pressure metastable single-bonded nitrogen allotrope was predicted using reliable theoretical methods. The predicted allotrope has a number of similarities with the experimentally detected cubic gauche nitrogen allotrope.

Two isomeric solid carbon nitrides with 1 : 1 stoichiometry which exhibit strong mechanical anisotropy

Two isomeric layered carbon nitride polymorphs are characterized using reliable theoretical methods. The NCNC phase, which is predicted for the first time, has a number of differences with the isomeric NCCN polymorph in its electronic, spectral and mechanical properties.

New carbon allotropes with metallic conducting properties: a first-principles prediction

Combining density functional theory computation and the global minimum structural search, we have found new α-, β-, and δ-phographene carbon allotropes.

Band-structure engineering in conjugated 2D polymers

The band structures of several conjugated 2D polymers are calculated through DFT and the influence of the polymer's repeat unit on its electronic structure is discussed.