Pristine Graphyne Research Articles

Boron-phosphorous doped graphyne: A near-infrared light absorber

The first-principle calculation with many-body effects explore the electronic and optical properties of newly designed ‘graphyne with BP at hexagonal ring’ (labeled as BP-yne). Our calculations show that BP-yne surface is a direct band gap semiconductor having band gap greater than pristine graphyne and this band gap value is sufficient to overcome the endothermic character of water-splitting reaction and further indicates its possible photocatalytic activities. The Raman and IR spectra analysis indicates quite different feature compare to its structural analogous ‘graphyne with 3BN at ring’ which may help to identify it during synthesis. Its optical absorption can be tuned from near-infrared to UV region depending on the polarization of electric field vector. The optical band gap, as well as the strong absorption peak, lies in the near-infrared region (NIR) and this promising trait can be exploited in biomedical arena.

Activating Graphyne Nanosheet via sp-Hybridized Boron Modulation for Electrochemical Nitrogen Fixation.

Exploring new metal-free catalysts with high activity for nitrogen reduction reaction (NRR) is highly desirable but remains a big challenge. Graphyne (GY) is a typical two-dimensional carbon material with many excellent properties. However, the NRR has rarely been envisaged on a GY-based metal-free catalyst up to now. Density functional theory calculations reveal that although pristine GY is inactive for N2 reduction, boron modulation can endow it with efficient activity toward NRR. Natural bond orbitals analysis, spin/charge density distributions, and free energy change diagrams are performed and discussed. Three boron doping formats including sp2-substituted, sp-substituted, and adsorbed configuration are considered. The obtained data show sp-substitution will induce local moderate spin and charge densities at the boron site on the GY surface, which is convenient for N2 adsorption and activation, and conductive to N-related intermediates formation and transformation. Moreover, the incorporated sp-hybridized boron can provide one empty p orbital and one occupied p orbital around itself, which plays a key role as an electron reservoir to accept electrons from and donate electrons to the adsorbed N-related species, and thus facilitate N2 reduction and ammonia synthesis. Henceforth, it provides more opportunities for preparing GY and other carbon materials as efficient catalysts toward renewable energy conversion and storage.

Electronic and optical properties of XN-ynes (X = B, Al, Ga): A first-principle study with many-body effects

This study aims to engineer electronic and optical properties of newly designed ‘graphyne with XN at hexagonal ring’ (labeled as XN-ynes, where X = B, Al, Ga). Except BN-yne, all XN-ynes are indirect band gap semiconductors, having larger gap than pristine graphyne. The Raman and IR spectra of XN-yne exhibit quite distinct feature with respect to pristine graphyne and strong Raman and IR line shows regular dependence on group IIIA element, thus may help to detect them during synthesis. The optical band gap calculated by G0W0 and Bethe-Salpeter equation (BSE) approach indicates the possibility of their usage as UV light absorber. The optical band gap is arises from π to π* transition. Not only optical band gap but also the strong absorption peak lies in UV region of electromagnetic spectra that also suggesting their possible use as UV light absorber. This study proposes an important initial step towards the applications of these newly designed XN-ynes.

Interaction properties of explosive vapors on γ-graphyne nanosheet – a DFT outlook

We employed ATK-VNL package to explore the electronic and adsorption features of graphyne nanosheet in order to ascertain the possibility to detect explosive vapors like octogen (HMX), pentaerythritol tetranitrate (PETN) and triacetone triperoxide (TATP). Initially, the structural stability of the prime material is ascertained by estimating cohesive energy. The significant electronic features like the projected density of states (PDOS) spectrum, band structure, and electron density are scrutinized for pristine graphyne nanosheets at atomistic levels. Then, upon surface assimilation of target explosive vapors on graphyne nanosheet, the electronic features and surface assimilation attributes like adsorption energy, Bader charge transfer, and average energy gap variation are computed. With the aid of the essential electronic and surface assimilation attributes, it is suggested that graphyne nanosheets can be employed as a prime material in detecting explosive vapors like octogen, pentaerythritol tetranitrate, and triacetone triperoxide.

DFT study of the electronic and structural properties of single Al and N atoms and Al-N co-doped graphyne toward hydrogen storage

Abstract In this work, electronic and structural properties of single Al or N atom doped and Al-N co-doped graphyne (GY) toward hydrogen storage were investigated using DFT-D calculations. Results show that N and Al atoms energetically prefer to lie instead of Csp in the chain and Csp2 in the hexagonal ring, respectively. Al or N doping changes conducting nature of GY from semiconductor to metallic. Pristine GY and more stable structures of Al doped, N doped and Al-N co-doped GY were examined for H2 adsorption. Adsorption energies for the first H2 molecule are about −0.140, −0.224, −0.141 and −0.288 eV/H2, respectively. They can hold 4, 9, 7 and 16 H2 molecules with average adsorption energy of ~−0.089, −0.158, −0.144 and −0.161 eV/H2, respectively. Also, the calculated corresponding hydrogen storage capacities reach up to 5.26, 10.17, 8.75 and 16.67 wt%, respectively. Although, effect of Al atom is more than N atom, when both of them co-doped in GY, its electronic and structural properties, as well as hydrogen storage capacity improve, extremely and they have a synergistic effect onto hydrogen adsorption. These findings show that N-Al co-doped GY can be used for designing new hydrogen storage materials in the future.

Sensing and elimination of the hazardous materials such as Sarin by metal functionalized γ-graphyne surface: A DFT study

Sarin is an organophosphorus compound, poisonous and deadly, which is used in the preparation of chemical weapons. We are looking for materials for using as sensing and capturing of Sarin, so the effect of Li, Ti, Fe and Ni single atoms on the structural and electronic properties of graphyne (GY) toward Sarin adsorption was investigated by DFT-D calculations. Seven sites of GY and different distances from GY plane were investigated to gain the best structure of M-decorated GY. Then, adsorption of Sarin on the pristine and M-decorated GY was considered. The results showed that H1 is the best site for metal decoration and Sarin adsorption. Pristine GY is a semiconductor with direct band gap about 0.431 eV. Metal intern causes to change GY character into semi-metallic and decrease GY band gap. Decoration with all metals improves adsorption energy of Sarin, extremely, e.g. up to 4.5 times for Ti-decoration. Among six examined sites of Sarin, for Ni-decoration, etheric oxygen and for others, oxygen of carbonyl group is the best site for adsorption. In all systems, charge transfer happens from Sarin and metal to GY sheet. Also, in presence of the Sarin molecule, the band gap values decrease. Adsorption energies, location of metal atoms, metal and Sarin charges, band structure and partial density of state (PDOS) diagrams were brought and discussed. Ultimately, our study shows that Li, Ti, Fe and Ni-decorated GY can be used as a promising candidate for sensing and capturing applications of CWAs such as Sarin.

Graphyne as the anode material of magnesium-ion batteries: Ab initio study

Graphyne, a single atomic layer structure of the carbon six-member rings connected by one acetilenic linkage, is a promising anode for the rechargeable batteries. In this paper, a first-principle study was carried out on graphyne as a new candidate for the anode material of magnesium-ion batteries, using density functional theory calculations. The main focus of this work is on the magnesium adsorption on graphyne surface. The structural properties such as adsorption height and energy, the most stable adsorption sites, the band structure, and density of state (DOS) of the pristine graphyne the diverse Mg-decorated graphyne structures, and energy barrier against Mg diffusion are also calculated. As a consequence of the band structure and DOS of graphyne structures, it is found that the pristine graphyne and the Mg-decorated graphyne structures show a semiconducting nature and metallic behavior, respectively. Moreover, the migration behavior of Mg on graphyne for the main diffusion paths is determined by Nudged Elastic Band (NEB) method.

Optimized Li storage performance of B, N doped graphyne as Li-ion battery anode materials

As the economy grows and the environment deteriorates, the renewable energy is urgently needed. The advanced energy storage technology in electronic equipment, electric vehicle, smart grid, etc. becomes more significant. For example, the rechargeable batteries, hydrogen storage media, supercapacitors, the new energy storage devices have received much attention today. The anodes of the lithium ion battery (LIB), as the main body of charging and discharging, should be most important. The ideal anode material for LIBs is required to possess a higher Li capacity and a lower volume expansion. Good reversibility and high Li capacity are balanced necessarily in the electrode material. The poor cycling performance of LIB is usually due to the severe volume expansion of anode in lithiation/delithiation process. In this paper, the Li storage performance of B and N doped graphyne is explored by using the density functional theory method. The Perdew-Burke-Ernzerhof functional of the generalized gradient approximation is chosen. The calculations indicate that the doping of B atoms can enhance the adsorption strength between the Li atom and the graphyne, which can greatly increase the Li storage capacity. The Li storage capacity of B doped graphyne can reach as high as 2061.62 mAh/g, which is 2.77 times that of pristine monolayer graphyne. Meanwhile, the B doping reduces the out-plane diffusion energy barrier of Li, but increases the in-plane diffusion energy barrier slightly by 0.1 eV. On the other hand, the doping of N atoms reduces the interaction between Li and graphyne, however, the Li capacity also increases to 1652.12 mAh/g because the number of the available Li adsorption sites increases. Moreover, the doping of N atoms greatly improves the diffusion performance of Li on graphyne. The in-plane diffusion energy barrier drops to 0.37 eV, and thus the charge-discharge performance of the N doping graphyne is well improved. Therefore, the doping of B and N atoms can remarkably improve the performance of graphyne as the LIB anodes. The remarkable performance of B and N doped graphdiyne shows that it will become a promising LIB anode in the future. The present research can provide a good theoretical basis and thus conduce to guiding the developing of good Li storage materials, and can also supply strong background for experimental researches.

Single tungsten atom supported on N-doped graphyne as a high-performance electrocatalyst for nitrogen fixation under ambient conditions.

Electrochemical reduction of dinitrogen molecules (N2) to value-added ammonia by using renewable electricity under mild conditions is regarded as a sustainable and promising strategy for N2 fixation. However, the lack of efficient, robust and inexpensive electrocatalysts for such electrochemical reduction has prevented its wide application. Herein, we report a novel single-atom catalyst, i.e., a single tungsten (W) atom anchored on N-doped graphyne (W@N-doped graphyne) as a highly efficient and low-cost electrocatalyst for the N2 reduction reaction. The inert N[triple bond, length as m-dash]N triple bond can be sufficiently activated when an N2 molecule is adsorbed on the W atom. A single atom of W coordinated with one N atom (doping into an sp-hybridized carbon atom) exhibits the highest catalytic performance with ultra-low onset potential of 0.29 V for N2 reduction reactions. The 'distal mechanism' is identified as the most favourable catalytic pathway. Moreover, the improved electrical conductivity of W@N-doped graphyne compared to that of pristine graphyne can ensure better electron transfer efficiency during the reduction processes. Our study provides a novel electrocatalyst with excellent catalytic performance for electrochemical reduction of N2 to NH3 under ambient conditions.

Investigation on probing explosive nitroaromatic compound vapors using graphyne nanosheet: a first-principle study

We studied the geometric stability of pristine graphyne nanosheet (Gpn-NS) and electronic properties for the possible use of graphyne sheet for the chemical sensor. The center of attention of the work is to probe the nitroaromatic compounds (NACs) at the earlier stage of chemical explosion using Gpn-nanosheet material. The geometric stability of pristine Gpn base material is entrenched with the formation energy and also verified with phonon band structure. The interaction of different NACs such as hexanitrostilbene, M-dinitrobenzene, picric acid, and 2,4,6-trinitrotoluene on Gpn material is studied in connection with the Bader charge transfer, average energy gap changes, adsorption energy, and band gap. Moreover, the adsorption energy of NACs on Gpn-NS varies in the order of − 0.178 to − 0.627 eV. The outcomes of the suggested work infer that Gpn-NS can be used to probe the NAC vapors.

Raman and IR signature of pristine and BN- doped γ-graphyne from first-principle

The present paper aims to provide in-depth analysis of Raman and IR spectra as well as the assigned vibrational modes of pristine and BN substituted graphynes, considering different dopant sites and concentrations. We have explored the implication of vibrational modes related with the Raman and IR line of pristine graphyne and BN-doped graphynes. The Raman and IR spectra of BN substituted graphyne show quite distinct feature than pristine graphyne and monolayer h-BN sheet. It also shows regular dependence on doping site as well as doping concentrations. Raman spectra help to detect the substitution site of BN while IR spectra help to identify the BN concentration. Hence the combination of IR and Raman spectra would be useful in detecting BN-doped graphyne during synthesis. Thus this study would help the experimentalist in sample characterization in near future.

Young's modulus of nanoporous γ-graphyne membrane using an atomistic finite element model

In this study, the Young's moduli of armchair and zigzag nanoporous graphyne membranes with various porosities, pore numbers, and pore arrangements were examined under tensile loading by using the atomic-scale finite element method. The results of this study were in agreement with that of a previous study regarding the Young's moduli of pristine graphyne membranes. According to our analysis, the Young's moduli of the armchair and zigzag graphyne membranes significantly decreased with an increase in porosity. Moreover, the porosity effect on the Young's modulus of a membrane with sixteen pores was greater than that of those with one pore. The pore arrangement effect on graphyne with high porosity was evident. This paper facilitates the understanding of the mechanical strength of nanoporous graphyne membranes and the fabrication and application of high performance nanoporous graphyne membranes.

Molecular simulation of penetration separation for ethanol/water mixtures using two-dimensional nanoweb graphynes

Abstract Graphyne is expected to be a new-class of highly-efficient sieving membranes due to its controllable uniform pore structure and ultrathin single-atom thickness. Herein, we computationally investigate the permeation performance of liquid ethanol–water mixtures across polyporous two-dimensional γ-graphyne sheets. It was found that, in the mixture, ethanol with larger molecular diameter permeates faster through the graphyne pores than water. The simulations demonstrate that pristine graphynes could act as highly-efficient ethanol-permselective membranes for separation of ethanol–water mixtures, with ethanol permeability remarkably higher than conventional membranes. This separation mechanism is distinctly different from the molecular-size dependent sieving process. The stronger hydrophobic interfacial affinity between graphyne and ethanol makes ethanol molecules preferentially adsorb on graphyne surface and selectively penetrate through graphyne pores. This penetration mechanism provides new understanding of molecular transport through atomically thick two-dimensional nanoporous membranes and this work is expected to be valuable in the potential development of highly-efficient membranes for liquid-phase mixture separation.

Detection of gas molecules on single Mn adatom adsorbed graphyne: a DFT-D study

As one of the prominent applications in intelligent systems, gas sensing technology has attracted great interest in both industry and academia. In the current study, the pristine graphyne (GY) without and with a single Mn atom is investigated to detect the gas molecules (CO, CH4, CO2, NH3, NO and O2). The pristine GY is promising to detect O2 molecules because of its chemical adsorption on GY with large electron transfer. The great stability of the Mn/GY is found, and the Mn atom prefers to anchor at the alkyne ring as a single atom. Upon single Mn atom anchoring, the sensitivity and selectivity of GY based gas sensors is significantly improved for various molecules, except CH4. The recovery time of the Mn/GY after detecting the gas molecules may help to appraise the detection efficiency for the Mn/GY. The current study will help to understand the mechanism of detecting the gas molecules, and extend the potentially fascinating applications of GY-based materials.

WITHDRAWN: Adsorption properties of the phosgene molecule on pristine graphyne, BN- and Si-doped graphynes: DFT study

WITHDRAWN: Adsorption properties of the phosgene molecule on pristine graphyne, BN- and Si-doped graphynes: DFT study

Doping and vacancy effects of graphyne on SO2 adsorption

The adsorption of sulfur dioxide (SO2) on pristine and modified graphyne (including boron- or nitrogen- doping and introducing a single carbon atom defect) was investigated by density functional theory calculations. The structural, electronic, and magnetic properties of graphyne were changed according to the dopant atom site of doping and vacancy. SO2 adsorption was obviously affected by modification of graphyne. SO2 weakly interacted with pristine and nitrogen-doped graphynes. Boron doping at the sp-hybridized carbon site and introducing a single carbon atom vacancy in graphyne brought about a dramatic enhancement in SO2 adsorption. The strongly chemisorbed SO2 at these active sites caused deformation of the graphyne structure and electron redistribution, which induced changes in the conductivity and magnetism of graphynes.

Adsorption properties of the phosgene molecule on pristine graphyne, BN- and Si-doped graphynes: DFT study

This work explores the influence of adatoms such as boron (B), nitrogen (N), and silicon (Si) on the activity of graphyne toward phosgene adsorption by the density functional theory (DFT) calculations. The adsorbent systems include virgin and doped graphyne, in which each adatom (B, N, and Si) is substituted for the carbon atom in the aromatic core. The adsorption energy, energy gap, molecular electrostatic potential, density of state, and work function are estimated to predict the adsorption behavior of phosgene over graphyne. The obtained results demonstrate the progressive change in the phosgene adsorption and exhibit a notable increase in negative values for adsorption energy by doping heteroatom in the molecular structure of adsorbent. The electronic perturbations induced by doped atoms, especially Si, enhance the sensitivity of graphyne toward the adsorbed phosgene, and the electronic properties are changed after phosgene adsorption in all complexes. A sensible justification for this observation can be provided by the energy gap analysis. Over the range of our study, B, N and Si-doped clusters can be introduced as promising chemical sensors for phosgene monitoring.

Electronic properties of aluminium and silicon doped (2, 2) graphyne nanotube

With the help of density functional theory (DFT) approach the electronic properties of Al and Si doped (2, 2) graphyne nanotube (GNT) has been investigated. We have chosen two doping positions. In one situation we have replaced one carbon atom by Al/Si atom in the chain position of the GNT and in other case we have substituted the carbon atom in the hexagonal ring by Al/Si atom. The result of the cohesive energy indicates that pristine graphyne nanotube shows highest stability whereas, Al doped at chain site of the GNT exhibits lowest stability. The density of states above and below the Fermi level for all these system is mainly contributed by carbon atom. Band structure analysis shows that the band gap can be tuned by functionalization of GNT with Al and Si atoms; which makes the possibility of using them in nano-electronic devices.

Metal decorated graphyne and its boron nitride analog as versatile materials for energy storage: Providing reference for the Lithium-ion battery of wireless sensor nodes

Based on density functional theory calculations, we investigate the boron substituted graphyne in terms of Li storage as well as metal-decorated graphyne and graphyne-like boron nitride layer (BN-yne) for hydrogen storage. Compared with pristine graphyne, the electric storage capacity and lithiation potentials of B-doped graphyne are improved significantly. The result can provide helpful information for the design and fabrication of anode materials of Lithium-ion battery, which is of crucial for the lifetime of wireless sensor nodes. Through the analyses of structural and electronic properties of graphyne and its boron nitride analog, we find that the most preferable adsorptive site of M (Ni, Cr, Pd) atom is the hollow site of 12-atom hexagonal ring. For hydrogen adsorption on M (Ni, Cr, Pd)-decorated graphyne and BN-yne, the hydrogen are not dissociated and all stored in molecular form. Due to the steric hindrance of the H2 molecules, each M (Ni, Cr, Pd) atom can adsorb up to three H2 molecules. The analyses of electronic properties show that the interactions between M (Ni, Cr, Pd) atom and H2 molecule are the hybridization between them and the polarization induced by electrostatic field of M (Ni, Cr, Pd) atoms. Our work demonstrates that metal decorated graphyne and its boron nitride analog are promising for energy storage.

Interaction of nitrogen molecule with pristine and doped graphyne nanotube

In this work the interaction of nitrogen molecule placed inside and outside (2, 2) pristine graphyne nanotube (PGNT) and doped graphyne nanotube (DGNT; D=Si, Al) have been investigated using density functional theory (DFT) with the help of generalized gradient approximation (GGA) to show the possibility of using graphyne nanotube in nano-electronics and also as a N2 gas sensor. The modulation of band gap is possible by interacting nitrogen molecule with PGNT and DGNT. The interaction of SiGNT and AlGNT systems with nitrogen molecule makes the possibility of using them as an extrinsic semiconductor. PGNT and SiGNT are non-magnetic in nature whereas AlGNT is magnetic. Projected density of state (PDOS) analysis shed insights on the contribution of the participating atoms. The electronic properties of PGNT do not change significantly due to the placement of nitrogen molecule but in case of DGNT the electronic properties are highly influenced. The Al-doped GNT may interact strongly with N2 molecule compared to PGNT and SiGNT.