As a promising photocatalytic material, g-C3N4 has drawn tremendous research interest. However, the fast charge recombination and narrow range of solar absorption restrain its practical application. ...Herein, for the first time, based on extensive hybrid functional calculations, graphyne (Gyne), a new two dimensional material, is used to form a layered vdW-nanohybrid with g-C3N4 to enhance the photoelectrocatalytic activity of g-C3N4. A comprehensive theoretical study of interfacial properties of g-C3N4/Gyne heterostructure including the band structure, partial density of state, optical absorption, wave functions, charge density difference, band alignment and photocurrent density is acquired to provide deep insight into the photocatalytic performance. The calculated results show that g-C3N4/Gyne heterostructure exhibits tremendous photocatalytic performance as that of recently experimentally synthesized Gyne family based nanocomposite, g-C3N4/graphdiyne (g-C3N4/GDyne). The designed g-C3N4/Gyne heterostructure has a fourfold increase in photocurrent density (0.937 μA/mm2) compared with that of g-C3N4 (0.233 μA/mm2). More importantly, the photocatalytic performance of g-C3N4/Gyne can be further improved by doping 2BN-pairs into Gyne layer. Theoretical prediction indicates that g-C3N4/2BN-Gyne even realizes a sevenfold increase in photocurrent density (1.669 μA/mm2) due to the type II band alignment, broadened light absorption range and much smaller effective mass, providing helpful physical mechanism information for further optimizing the optoelectronic properties of g-C3N4/GDyne and g-C3N4/Gyne. Our theoretical work provides stepping stone into the design of highly efficient g–C3N4–based photocatalysts and a fully coherent picture about the interfaces of g-C3N4/GDyne and g-C3N4/Gyne heterostructures can also be obtained.
•The g-C3N4/graphyne heterostructure possesses tremendous photocatalytic performance than isolated g-C3N4.•Type-I/type-II transition of g-C3N4/graphyne heterostructure can be induced by doping 2BN-pairs into Gyne layer.•The g-C3N4/2BN-graphyne heterostructure realizes a sevenfold increase in photocurrent density compared with that of g-C3N4.•The g-C3N4/2BN-graphyne heterostructure could satisfy the redox potentials of H2O splitting and CO2 reduction.
•Graphyne is explored as a carrier for daunorubicin drug.•Graphyne possess significant therapeutic potential as a drug carrier.•For visual explanation of different excited-states, PET process and ...electron-hole theory are used.
In this research, for the first time; graphyne is investigated as a carrier for delivery of anticancer drug, daunorubicin. The effectiveness of graphyne as a carrier, is explored with the help of calculations of some physiochemical properties such as band-gap, dipole-moment, and chemical-reactivity-descriptors for daunorubicin drug, graphyne carrier and daunorubicin-graphyne complex by using Density Functional Theory (DFT) method. Daunorubicin has significant antimitotic and cytotoxic activity as it can form complex with DNA by intercalation. The nature of interactions between graphyne and daunorubicin complex are clarified through noncovalent-interaction (NCI) analysis, which demonstrated that Vander-Waals force of interactions are present between the graphyne carrier molecule and daunorubicin drug. Daunorubicin drug will easily off-load at the target point as weak forces are present between drug and graphyne carrier. Frontier-molecular-orbital-analysis explained that how charge-transferred from daunorubicin to graphyne in complex formation process. The charge-transfer process is further studied by charge-decomposition-analysis (CDA). The calculations at excited-state indicated that the λmax of daunorubicin-graphyne complex show red-shift of 91 nm. PET process is also studied for excited-states of daunorubicin-graphyne complex with the help of electron-hole theory and it revealed that fluorescence-quenching process will occur in complex molecule. The process of fluorescence-detection is very useful for systematic delivery of daunorubicin drug at target site for the perfect treatment. Moreover, the effect of + 1 and −1 charge-state on graphyne molecule and its complex with daunorubicin is also investigated. Overall, the calculations suggested that graphyne could be utilized as an efficient carrier for targeted-delivery of daunorubicin.
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•Functional in-situ S-doped graphyne was bottom-up synthesized through a solvent-free mechanochemical strategy.•The mechanochemical reactions between calcium carbide and ...tetrabromothiophene is efficient, green and controllable.•The resultant S-doped graphyne features unique composition and structure with alkynyl-linked thienyl carbon skeleton.•The resultant S-doped graphyne exhibits high application performance in Hg(II) adsorption and energy storage.•This work provides an innovative perspective for the structure expansion and application development of graphynes.
Two-dimensional alkynyl carbon materials have great application prospects, and the in situ doping can further regulate their performance and structure–property relation. However, the “bottom-up” synthesis strategy of doped graphyne for energy and environmental fields is rarely studied. In this work, a S-doped graphyne (S-GY) was successfully synthesized through solvent-free mechanochemical reaction of calcium carbide and tetrabromothiophene. The synthesis process is efficient, green and controllable. The resultant S-GY possesses unique composition and alkynyl-linked thienyl carbon skeleton with hierarchical porosity, in-situ S doping, nanosheet morphology and well-ordered internal structure. Further, the S-GY exhibits excellent Hg(II) adsorptivity of 869.6 mg g−1, and supercapacity performance with good electrical conductivity, excellent long cycle stability and high specific capacitance (415.6 F cm−3). The proposed strategy is helpful to promote the structural expansion of graphynes, boost the application of two-dimensional alkynyl carbon materials, and thus may provides a new perspective for the development of novel carbon materials.
Inspired by the great development of graphene, more and more research has been conducted to seek new two-dimensional(2D) materials with Dirac cones. Although 2D Dirac materials possess many novel ...properties and physics, they are rare compared with the numerous 2D materials. To provide explanation for the rarity of 2D Dirac materials as well as clues in searching for new Dirac systems, here we review the recent theoretical aspects of various 2D Dirac materials, including graphene, silicene, germanene,graphynes, several boron and carbon sheets, transition-metal oxides(VO2)n/(TiO2)m and(CrO2)n/(TiO2)m, organic and organometallic crystals, so-MoS2, and artiicial latices(electron gases and ultracold atoms). heir structural and electronic properties are summarized. We also investigate how Dirac points emerge, move, and merge in these systems. he von Neumann–Wigner theorem is used to explain the scarcity of Dirac cones in 2D systems, which leads to rigorous requirements on the symmetry,parameters, Fermi level, and band overlap of materials to achieve Dirac cones. Connections between existence of Dirac cones and the structural features are also discussed.
The structural, electronic, and optical characteristics of multilayer C δ‐graphyne and δ‐graphyne‐like BN sheets are discussed by first‐principles study. The calculations approved that the sheets are ...energetically favorable and thermally stable. The layers are held together by van der Waals forces. The mono‐ and tri‐layer C δ‐graphyne exhibit semimetallic behavior, while bi‐ and tetra‐layer C δ‐graphyne are semiconductors with negligible bandgap. All multilayer BN δ‐graphyne sheets are insulators with indirect bandgap. The bandgap increases with increasing number of layers. The optical behavior of the structures is anisotropic under electric fields polarized parallel and perpendicular to the sheets. The sheets exhibit high static dielectric constants, optical absorption, and optical conductivity. The electronic and optical characteristics of C and BN δ‐graphyne sheets promise their progress and application in the world of optoelectronics.
The structural, electronic, and optical characteristics of multilayer δ‐graphyne and δ‐graphyne‐like BN sheets are studied by density functional theory. Mono‐ and tri‐layer δ‐graphyne are semimetals, while bi‐ and tetra‐layer δ‐graphyne are semiconductors. Multilayer δ‐graphyne‐like BN sheets are wide bandgap insulators. These sheets are proper for use in nano‐optoelectronic devices due to their promising electronic and optical characteristics.
This review aims to offer a comprehensive and critical understanding of mechano-chemical synthesis of γ-graphyne (γ-GY). Through the discussion of reaction mechanism and synthetic limits, it is ...verified that the product indeed contains the compound of γ-GY, but the defects such as graphitized carbon introduced in the process are inevitable.
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•A comprehensive insight into the mechanochemical synthesis of full-carbon graphyne material including its advances and limits.•The key synthetic strategies for graphyne carbon and corresponding characterization results are summarized and discussed.•Previous origin (environmentally mechanochemical dehalogenation) and subsequent developments (synthesis for other alkynyl cross-linked carbon derivatives) for mechanosynthesic graphyne are introduced in detail.•Fabrication mechanism of γ-graphyne via the mechanochemcial synthesis is specifically elucidated and carbonaceous impurities are inevitably induced during the process.•Future development suggestions for mechanochemical preparation of graphyne material are proposed.
Graphyne, a novel regularly sp-/sp2-hybridized carbon allotrope, has attracted significant interest in synthetic chemistry and various applications. As a promising approach for material synthesis, mechanochemistry has first been successfully applied to fabricate γ-graphyne (γ-GY) which exhibits highest structural stability among graphyne family and possesses fascinating properties like a direct bandgap and unique nanoporosity. The γ-GY skeleton forms via an alkyne nucleophilic cross-coupling reaction induced by intense mechanical energy using hexahalobenzene and calcium carbide as precursors. This mechanochemical strategy is simple, high-yielding, scalable, and commercially viable. This review aims to offer a comprehensive and critical understanding of mechanochemical synthesis of γ-GY. Firstly, the basic concept, physicochemical properties and potential applications of graphyne, especially γ-GY, are introduced. Subsequently, the review summarizes several state-of-the-art synthetic strategies for γ-GY and corresponding representative characterizations. Furthermore, the feasibility of mechanosynthesis for γ-GY is elucidated through the discussion of its origin which involves mechanochemical dehalogenation, and its subsequent development for the synthesis of alkynyl cross-linked carbon derivatives. The reaction mechanism, and controversial factors (including solvent issue, side reaction, and carbonaceous impurities) of the mechanochemical route are adequately outlined and analyzed. Evidence confirms the existence of γ-GY in the as-prepared sample and inevitable generation of by-products such as carbonaceous impurities. Finally, the challenges and future research directions of mechanochemical synthesizing high-quality γ-GY and derivatives (analogues) are proposed.
•α-graphyne systems demonstrate significant potential for H2 adsorption.•Alkali metal decoration enhances H2 adsorption in α-graphyne systems.•Interlayer forces can increase H2 storage capacities in ...bilayer systems.•The bilayer system can enhance the H2 adsorption density between α-graphyne layers.
Using the first-principles density functional theory, the hydrogen storage properties of monolayer and bilayer α-graphyne systems decorated by alkali metal are investigated. The results of band structure and density of state analysis indicate that alkali metal decoration enhances the chemical activity of the adsorption substrate, leading to increased H2 adsorption capacities for Li, Na and K decorated monolayer systems (15.0 wt.%, 14.5 wt.%, 10.7 wt.%, respectively). The combined action of interlayer force and decorated metal atoms results in higher H2 adsorption capacities for Li, Na and K decorated bilayer systems (17.7 wt.%, 16.9 wt.%, 13.0 wt.%, respectively), which means the bilayer graphyne structures enhance the storage capacities for decorated structures. Additionally, the Na decorated rhombus bilayer system demonstrates the highest adsorption density of H2 molecules between α-graphyne layers. Overall, alkali metal decorated monolayer and bilayer systems exhibit promising H2 adsorption potentials.
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Two dimensional γ-graphyne was successfully prepared by the ultrasonic vibration of the mixture of CaC2 and PhBr6 in absolute ethanol and its superior performance as electrode materials in ...supercapacitor and photoelectrochemical catalysis was demonstrated.
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•2D γ-graphyne was prepared by sonochemical reaction of CaC2 and PhBr6 in ethanol.•The successful fabrication of γ-graphyne was systematically characterized.•Superior electrochemical performance of γ-graphyne in supercapacitor was demonstrated.•Photoelectrochemical catalytic properties of γ-graphyne were investigated.
As a novel type of carbon materials, graphynes possesses the merits of high carrier mobility and large surface areas, etc. However, to date, the main research of graphynes is focused on theoretical calculation whereas few strategies have been reported for the fabrication of graphynes. In this work, a facile method named ultrasound-promoted synthesis was developed to fabricate γ-graphyne using PhBr6 and CaC2 as the raw materials. The reaction system in argon atmosphere ultrasonically vibrated for 24 h in the ultrasonic bath at a power of 180 W and frequency of 53 kHz. The structure, morphology, and component of the obtained samples were detected by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, FT-IR spectra, scanning electron microscopy, transmission electron microscopy, and the selected area electron diffraction. The electrochemical and photoelectrochemical measurements indicate that γ-graphyne can be used as superior electrode mateirals in supercapacitor and photoelectrochemical catalysis. From the results of galvanostatic charge/discharge measurements, the γ-graphyne supercapacitor delivers a maximum specific capacitance of 81 F/g at 0.2 A/g and a capacitance retention rate of 87.5% after 5000 cycles at 3 A/g. Moreover, UV-vis light photoelectrochemical response and high carrier density are observed for γ-graphyne. It is also demonstrated that the charge-transfer resistance is low by Tafel slopes and Nyquist plots. This work puts forward a new and facile strategy for the fabrication of γ-graphyne and explores its application in the field of solar energy conversion and storage.
By regulating the doping site and concentration of Li atoms in β1-Graphyne, more charges accumulate on the surrounding C atoms and the gas-framework interaction increase, thus creating a favorable ...environment for CO2 adsorption and an ultra-high CO2 adsorption capacity and CO2/N2 selectivity in Li-β1-GYs.
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•Li-β1-GYs exhibit an ultra-high CO2 adsorption capacity and CO2/N2 selectivity.•Li doping has a more pronounced effect on enhancing the CO2−Li-β1-GYs interaction.•Gas distribution analyses demonstrate Li doping provides more adsorption sites.
The selective CO2 adsorption is of great significance to many energy and environment-related processes. Herein, CO2/N2 adsorption and separation in Li-doped 2D graphyne allotrope (β1-GY) were studied by using grand canonical Monte Carlo simulation and density(GCMC) functional theory approaches(DFT). The results showed that Li atoms were stably combined with β1-GY and the binding energy was −2.85−−3.60 eV, which ensured the structural stability of Li-doped β1-graphyne (Li-β1-GY) for CO2/N2 adsorption and separation. Different Li doping types were evaluated, and five Li-β1-GY structures were screened, including the a, b, c, ac, and bc structures. Li doping provided more adsorption sites and improved the CO2 adsorption performance. Among all Li-β1-GYs, the ac structure showed the best CO2 adsorption performance. The CO2 adsorption capacity of ac structure reached 11.10 mmol−1 g−1 at 298 K and 100 kPa, which was higher than the well-known metal–organic framework Mg-MOF-74 (∼8.60 mmol−1 g−1) under the same condition. At 298 K and 100 kPa, the CO2/N2 selectivity reached 354. The gas distribution confirmed that CO2 was adsorbed around the Li and C atoms and demonstrated the significant improvement of C atoms around Li atoms on the CO2 adsorption. The interaction analyses showed that Li doping enhanced the CO2-framework interaction more distinctively than the N2-framework interaction, leading to an ultra-high CO2 adsorption capacity and CO2/N2 selectivity. Results of this work highlighted Li-β1-GYs as promising materials for CO2/N2 adsorption and separation.
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