Single Layer Blue Phosphorus Research Articles

Enhanced hydrogen storage of single-layer blue phosphorus by synergistic effect between doped lightweight elements and grafted lithium atoms

Single-layer blue phosphorus (SLBP) has displayed charming photoelectric performances, but its property in hydrogen storage is not outstanding due to the weak interactions. To expand the application of SLBP in hydrogen storage, we attempt to screen SLBP-based materials with stable structures and strong polarity using density functional theory by doping lightweight elements and grafting alkali metal atoms. The simulation results indicate that the lightweight elements (B, C, N, O and F) doped SLBP systems have more stable structures due to the strong orbital interaction than pure SLBP, and exhibit electron deficient characteristics. Compared to the pure SLBP, the H2 adsorption energies of the doped systems improve and range from 0.05 to 0.09 eV, but it still cannot meet the requirements of ideal hydrogen storage. Therefore, the lightweight element doped SLBP systems are further grafted by Li atom. Under the synergistic effect of doping lightweight elements and grafting Li atoms, H2 molecules are strongly polarized, and the corresponding adsorption energies of H2 reach to 0.16, 0.26, 0.28, 0.30, and 0.10 eV, respectively. It is worth emphasizing in the C-doped SLBP system that the hydrogen storage capacity of reaches 5.53 wt% for each Li atom adsorbs one hydrogen molecule and the corresponding adsorption energy is 0.23 eV/H2 when the ratio of C to P atoms increases to 6:26. For each Li atom adsorbs two hydrogen molecules in the same hydrogen storage system, the hydrogen storage capacity reaches 10.48 wt% with 0.18 eV/H2 adsorption energy. We hope these results can provide theoretical basis and scientific guidance for searching for SLBP-based materials with excellent hydrogen storage performances at ambient temperature.

Blue phosphorene on Au(111): theoretical, spectroscopic and diffraction analysis reveal the role of single Au adatoms.

In investigating the monoatomic layers of P, several stable two-dimensional (2D) allotropes have been theoretically predicted. Among them, single-layer blue phosphorus (BlueP) appears to deliver promising properties. After initial success, where the structure of BlueP triangular patches on Au(111) was conceived on the basis of scanning tunneling microscopy (STM) and density functional theory (DFT), the surface structure model was revisited multiple times with increasing accuracy and insight of theoretical calculations and experimental datasets. Interestingly, the quest for a reliable atomic structure model of BlueP on Au(111) turned out to be very contentious and challenging, particularly considering the possible incorporation of Au atoms in the 2D sheet of P. This article proposes an extended report on theoretical findings that can be extracted from DFT calculations of the orbital projected band structure and employed for an efficient comparison protocol between the calculations and experimental datasets obtained from angle-resolved photoemission spectroscopy (ARPES). The findings, together with experimental and simulated data from STM imaging and surface X-ray diffraction (SXRD), show a clear way to verify the presence and characterize the stabilizing effect of foreign atoms in 2D materials.

On the development of continuum material models for 2D materials from Density Functional Theory data

AbstractA multiscale framework is presented for the development of continuum models for 2D materials. The framework consists of four steps. First the 2D material is studied by performing a set of Density Functional Theory (DFT) simulations. A continuum model consistent with the material properties is then developed. The continuum model is calibrated based on the generated DFT data. Finally, the model is validated from new DFT data. The generation of DFT results and the calibration of the continuum model are discussed in this paper and a numerical example of a pressurized square phosphorus sheet is presented. The framework has previously been applied to graphene and single layer blue phosphorus.

A nonlinear hyperelasticity model for single layer blue phosphorus based on ab initio calculations

A new hyperelastic membrane material model is proposed for single layer blue phosphorus ( β -P), also known as blue phosphorene. The model is fully nonlinear and captures the anisotropy of β -P at large strains. The material model is calibrated from density functional theory (DFT) calculations considering a set of elementary deformation states. Those are pure dilatation and uniaxial stretching along the armchair and zigzag directions. The DFT calculations are performed with the Quantum ESPRESSO package. The material model is compared and validated with additional DFT results and existing DFT results from the literature, and the comparison shows good agreement. The new material model can be directly used within computational shell formulations that are, for example, based on rotation-free isogeometric finite elements. This is demonstrated by simulations of the indentation and vibration of single layer blue phosphorus sheets at micrometer scales. The elasticity constants at small deformations are also reported.

Strain-induced effects in zigzag-edged blue phosphorene nanoribbons with edge sulfur passivation

Motivated by the recent successful growth of quasi-free-standing single layer blue phosphorus (BlueP) on tellurium functionalized Au(1 1 1) by using black phosphorus as the precursor (Zhang et al 2016 Nano Lett. 16 4903; Gu et al 2017 ACS Nano 11 4943), here we study the strain performance for zigzag BlueP nanoribbons (zBluePNRs) with different edge chemical modifications. Based on the first-principles calculations, interestingly, we find that a narrow zBluePNR of width up to ∼2 nm with edge sulfur (S) passivation under an uniaxial strain exhibits an important effect of negative Poisson’s ratio because of the particularity of the P–S bonds at edges, and as the ribbon width further increases the Poisson’s ratio varies from negative to positive. Meanwhile, the S-passivation also induces magnetism, and applying a strong enough strain can transfer this zBluePNR from magnetic metal state to half-metal one. All these physical properties are discussed in connection with the variation of microstructure of the ribbons. Our findings may paving the way for both a fundamental understanding of nanoscale physics and applied device engineering.

Electronic structure and hydrogen storage properties of Li–decorated single layer blue phosphorus

Single layer blue phosphorus (SLBP) is a promising two–dimensional material for nanoelectronic devices, but the electronic structure and hydrogen storage property of modified SLBP received little attention. Li atoms can be strongly bonded on SLBP in a 1:1 Li/P ratio with a binding energy larger than the cohesive energy of bulk Li. The geometric structure of SLBP suggests the 3s3p orbitals of the P atom hybridize in sp3 manner. But our analyses show that the 3s and 3p orbitals form bonding and antibonding orbitals respectively. The 3s orbitals are fully occupied as they have much lower energies, and the bonding orbitals formed by P 3p are occupied in pure SLBP. The decorated Li atoms transfer their 2s electrons to the antibonding orbital formed by P 3p. The Li atoms exist as +1 cations and they are ionically bonded on SLBP. H2 molecules adsorbed on the Li+ cations are strongly polarized and form strong adsorption. When two H2 are adsorbed on each Li atom decorated at the 1:1 Li/P ratio, the hydrogen storage capacity reaches 9.52 wt% but the H2 molecules are arranged in two layers with the adsorption energy −0.168 eV/H2. When the Li atoms are decorated alternatively on the two sides of the P6 rings with a Li/P ratio of 1:2, each Li atom can absorb two H2 molecules in a single–layer; the hydrogen storage capacity is 5.48 wt% and the adsorption energy reaches −0.227 eV/H2. These results mean the Li–decorated SLBP can work at ambient temperature with high reversible hydrogen storage capacity.

Growth of Quasi-Free-Standing Single-Layer Blue Phosphorus on Tellurium Monolayer Functionalized Au(111).

Blue phosphorus, a newly proposed allotrope of phosphorus, represents a promising 2D material with predicted large tunable band gap and high charge-carrier mobility. Here, we report a simple method for the growth of quasi-free-standing single layer blue phosphorus on tellurium functionalized Au(111) by using black phosphorus as the precursor. In situ low-temperature scanning tunneling microscopy (LT-STM) measurements were used to monitor the growth of the single-layer blue phosphorus, which forms triangular structures arranged hexagonally on the tellurium layer. As revealed by in situ X-ray photoelectron spectroscopy, LT-STM measurements, and density functional theory calculation, the blue phosphorus layer weakly interacts with the underlying tellurium layer.

Epitaxial Growth of Single Layer Blue Phosphorus: A New Phase of Two-Dimensional Phosphorus.

Blue phosphorus, a previously unknown phase of phosphorus, has been recently predicted by theoretical calculations and shares its layered structure and high stability with black phosphorus, a rapidly rising two-dimensional material. Here, we report a molecular beam epitaxial growth of single layer blue phosphorus on Au(111) by using black phosphorus as precursor, through the combination of in situ low temperature scanning tunneling microscopy and density functional theory calculation. The structure of the as-grown single layer blue phosphorus on Au(111) is explained with a (4 × 4) blue phosphorus unit cell coinciding with a (5 × 5) Au(111) unit cell, and this is verified by the theoretical calculations. The electronic bandgap of single layer blue phosphorus on Au(111) is determined to be 1.10 eV by scanning tunneling spectroscopy measurement. The realization of epitaxial growth of large-scale and high quality atomic-layered blue phosphorus can enable the rapid development of novel electronic and optoelectronic devices based on this emerging two-dimensional material.