The diatomic catalyst synthesized by high-temperature thermal cracking usually undergoes structural reorganization of raw materials, increasing the difficulty in studying the structure-activity ...relationship of the catalysts. Herein, starting from the synthesis methodology, we adjust the atomic spacing of dual-Pd-site catalysts to 0.4 and 0.8 nm by regulating the monomer structure of graphyne. The model experiment of nitrobenzene reduction shows that graphyne catalyst (TEGY-Pd) with closer palladium atom spacing (0.4 nm) show a faster reaction rate (1.57 min−1), good universality and cyclic stability in catalytic process than that of graphdiyne catalyst (TEGDY-Pd) which has longer palladium atom spacing. Moreover, the theoretical calculation shows that the excellent catalytic performance of TEGY-Pd is original from the synergetic catalysis of the closer diatomic palladium to the nitro group in adsorption and electron transport process. This work provided a new idea to precisely control the metal atomic spacing and revealed the structure activity relationship of binuclear catalysts.
The atomic spacing of diatomic palladium catalysts was adjusted. TEGY-Pd with closer palladium atom spacing shows the synergistic dipole effect in nitrobenzene reduction reaction. Display omitted
•Two dual-Pd-site catalysts were synthesized by non-thermal cracking method.•The atomic spacing of diatomic Pd catalysts was adjusted by regulating the monomer structure of graphyne.•The oxygen atom in the -NO2 group is more firmly combined with closer dual Pd sites.•The reasonable distance of Pd atoms could realize synergistic dipole effect to the reactant.
Topological indices serve as mathematical tools for characterising the molecular structure of a compound, and are useful to anticipate its properties. Actually, these are quantitative measures that ...can provide valuable information regarding the structure of a molecule, such as its connectivity and symmetry. By analysing these indices, researchers can make predictions about the behaviour of the molecule, such as its reactivity, solubility, and toxicity, among others. The γ-Graphyne is a fascinating carbon allotrope that has recently gained significant attention due to its unique electronic, optical, and mechanical properties. As a result, there has been increasing interest in exploring its potential applications in various fields of science and technology. The molecular descriptors for the characterisation of γ-Graphyne have not yet been investigated. Therefore, it is of much importance to predict its molecular topology to well understand the physicochemical properties. In this work, a graph theory-based edge partitioning technique is used to model the molecular topology of γ-Graphyne and Zigzag graphyne nanoribbon, and mathematical closed-form expressions for some of its essential degree-based molecular descriptors are derived. These computed indices have been illustrated with the help of graphical representations and numerical tables.
Molecular dynamics simulations are used to study the mechanical properties of α-graphyne and α2-graphyne. The square and rectangular α-graphyne and α2-graphyne with different dimensions are modelled. ...It is seen that for both of the considered nanosheets, Young's modulus is smaller than along the armchair direction than along the zigzag direction. Similarly, zigzag α-graphyne has larger fracture strain than the armchair one. For the α2-graphyne, however, the fracture strain along the armchair direction is larger than zigzag direction. Besides, it is observed that Young's modulus of the α-graphyne is smaller than α2-graphyne for both of the armchair and zigzag structures. However, the α-graphyne possesses larger fracture strain than α2-graphyne. It is also seen that Young's modulus of the square α-graphyne and α2-graphyne nanosheet is not dependent on the nanosheet dimension. However, fracture strain and maximum stress of these nanosheets decrease by increasing the nanosheet size. Finally, the Poisson's ratio of the α-graphyne and α2-graphyne is obtained as large as 0.9 for some sizes.
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•MD simulations are used to study the mechanical properties of α-graphyne and α2-graphyne.•The square and rectangular α-graphyne and α2-graphyne with different dimensions are modelled.•For both α-graphyne and α2-graphyne, Young’s modulus along the armchair direction is smaller than zigzag direction.•Zigzag α-graphyne has larger fracture strain than the armchair one.•Fracture strain along the armchair α2-graphyne is larger than zigzag one.
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.
As a new member of the carbon family, γ-graphyne is combined with SrTiO3 for the first time in this paper, and a series of SrTiO3/γ-graphyne heterostructures are synthesized by a simple impregnation ...method. The as-prepared heterostructures are investigated by a series of characterizations, and the optimal content of γ-graphyne (γ-GY) is determined to be 1.0 wt%. After γ-GY modification, the maximum photocurrent and current density are enhanced by 30 and 5 folds, respectively, and the excitation and separation of photogenerated charges enhanced. In addition, the degradation of methylene blue by the heterostructured SrTiO3/γ-graphyne under visible light irradiation reached 88 % in 30 min with a photocatalytic rate of 6.277 × 10−2min−1, enhanced by 3.04 times compared with SrTiO3. The degradation properties are also proved by Rhodamine B degradation tests. The excellent stability and recyclability of the catalysts are proved. And h+, •O2−, and •OH are demonstrated to play roles in the reaction process, with •OH being the main active substance. A possible photocatalytic mechanism is further suggested. This work sheds light on the design of γ-GY modified composites for photoelectrochemical and photocatalytic applications.
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•The 2D γ-graphyne is assembled onto SrTiO3 particles by simple wet impregnation and stable heterojunctions are formed.•The SrTiO3/γ-GY composites are characterized by high photoelectrocatalytic activity and exhibit excellent photocatalytic performance for MB photodegradation tests.•The successful combination of γ-GY and SrTiO3 expands light absorption range and reduces carrier recombination.•γ-graphyne nanosheets provide fast transfer channels and electron sinks for carrier migration and separation.
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•The design of advanced electrocatalysts is crucial in the CO2 reduction reaction (CRR).•Single transition metals like Cr are known for high electrocatalyzing potential in CRR.•CRR ...efficiency of transition metals was checked after embedment into graphyne (GY).•Cr-GY is the best option to yield CH4 with an ultralow limiting potential of −0.29 V.
The design of advanced electrocatalysts is key for capturing chemically inert CO2 for conversion into value-added products (e.g., fuel) and to effectively mitigate greenhouse gas emissions and energy crisis with high standards of sustainability. However, control of product selectivity at a low overpotential is a challenge. In this work, the electrocatalyzing potential of different single transition metals (including Ti, V, Cr, and Mn) was explored in the CO2 reduction reaction (CRR) based on density functional theory (DFT). The efficiency of CRR was examined for each transition metal in relation to their reaction intermediates (COOH, CO, and CHO) after being embedded into graphyne (GY) systems. Accordingly, embedding Cr into GY is the most efficient option for the CRR to produce CH4 with an ultralow limiting potential of −0.29 V based on reaction energies and barriers. For the hydrogen evolution reaction (HER), CO2 is more advantageous to preferentially occupy the activation site than H2 on Cr-GY to reflect their differences in the adsorption energy (-0.83 vs. −0.38 eV). At the same time, Cr-GY can effectively inhibit the HER in the CRR process with the limiting potential of HER as −0.34 V. The overall results of this research are expected to deliver a new path for the development of low-potential electrocatalysts with high activity and selectivity for reduction of CO2.
The 2D graphyne-related scaffolds linked by carbon–carbon triple bonds have demonstrated promising applications in the field of catalysis and energy storage due to their unique features including ...high conductivity, permanent porosity, and electron-rich properties. However, the construction of related scaffolds is still mainly limited to the cross-linking of CaC2 with multiple substituted aromatic halogens and there is still a lack of efficient methodology capable of introducing high-concentration heteroatoms within the architectures. The development of alternative and facile synthesis procedures to afford nitrogen-abundant graphyne materials is highly desirable yet challenging in the field of energy storage, particularly via the facile mechanochemical procedure under neat and ambient conditions. Here, in this study, graphyne materials with abundant nitrogen-containing species (nitrogen content of 6.9–29.3 wt.%), tunable surface areas (43–865 m2 g-1), and hierarchical porosity are produced via the mechanochemistry-driven pathway by deploying highly electron-deficient multiple substituted aromatic nitriles as the precursors, which can undergo cross-linking reaction with CaC2 to afford the desired nitrogen-doped graphyne scaffolds efficiently. Unique structural features of the as-synthesized materials contributed to promising performance in supercapacitor-related applications, delivering high capacitance of 254.5 F g-1 at 5 mV s-1, attractive rate performance, and good long-term stability.
We compute electronic density of states, thermodynamic and optical conductivities of β-graphyne layer under applying biaxial strains. Particularly, the imaginary part of dielectric constant, which is ...proportional to the electromagnetic wave absorption rate, of β-graphyne due to the magnetic field and biaxial strain effects has been calculated. The temperature dependence of Pauli spin susceptibility and specific heat of the structure under applying magnetic field has been found. Tight binding model Hamiltonian has been applied for describing electron dynamics in β-graphyne layer in the presence of magnetic field. The effects of biaxial in-plane strain on the frequency behavior of the imaginary part of optical dielectric constant of β-graphyne layer. Linear response theory and Green’s function approach have been exploited to obtain the frequency behavior of optical behavior of the structure. Moreover, the frequency dependences of transmissivity and reflectivity of electromagnetic wave between two media separated by a β-graphyne layer are given. Our numerical results indicate that the frequency dependence of optical absorption shows a monotonic decreasing behavior for each compressive and tensile strain parameter. Also, the frequency dependence of transmissivity and reflectivity of electromagnetic wave between two media separated by β-graphyne layer for normal incidence has been investigated due to the effects of magnetic fields and strain parameters. The spin susceptibility of β-graphyne layer increases with magnetic field at fixed temperature however decreasing behavior for susceptibility is found for each value of magnetic field.
•The investigation of optical absorption of beta graphyne layer in the presence of Strain.•The study of transmission and reflection of electromagnetic wave between two media separated by graphyne layer.•The study of specific heat due to biaxial strain.
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•Electronic and structural properties of the oxygenated graphyne were studied.•Adsorption of CO, CO2 and NH3 onto graphyne oxide was considered.•Oxygen trends to join to sp-hybridized ...carbon atoms and forms carbonyl group.•Altering the oxygen coverage in a supercell can tune the electronic properties.•Adsorption energies are dependent to number and site of O atoms.
Graphyne (GY), a 2D carbon allotrope, has excellent electronic properties. Similar to other carbon structure, changing in some of the electronic and structural properties causes to promote its practical applications. Functionalization is one of the best methods for this objective. In this work, insertion of one to four oxygen atoms in various sites of the GY by DFT-D and molecular dynamic (MD) calculations were performed to study the corresponding electronic and structural properties of the oxidized graphyne. Then, adsorption of CO, CO2 and NH3 was considered. Results show that insertion of one to four oxygen atoms forms very stable oxides with much larger binding energies than graphene. Oxygen trends to join to sp-hybridized carbon atoms and forms carbonyl and epoxy groups that carbonyl is more stable. Also, insertion of the first O atom increases adsorption energies and decreases band gap values, while insertion of the second O atom has inverse treatment. Altering the oxygen coverage through changing the number of oxygen atom in a supercell can tune the electronic properties. For three adsorbed molecules, the best site and orientation for adsorption were determined and discussed. It was seen that adsorption to GYO is stronger than GY and GYO2.
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•Dopant Fe atom can be firmly embedded in γ-graphyne (GY-Fe) and break surface chemical inertness.•GY-Fe surface is beneficial to the adsorption of gas molecules (O2, CO, NO, NO2, and ...SO2).•Gas molecules are firmly anchored on GY-Fe plane through the formation of chemical bonds.•Modified γ-graphyne sheet may be a potential substrate to design gas sensor and catalysts.
The adsorption behaviors of gas molecules O2, CO, NO, NO2 and SO2 on the surface of γ-graphyne doped with Fe atom were explored in detailed by first principles calculations. It is found that dopant Fe atoms could be embedded stability into the γ-graphyne plane with the lower binding energy, the modified surface could significantly enhance the adsorption capacity for free gas molecules. Gas molecules are anchored firmly at the surfaces through the formation of chemical bonds with Fe dopant atoms, the typical chemisorption behaviors can be confirmed by the analysis of electronic properties. The OO bond is elongated to 1.412 Å because of the chemical interaction between adsorbed O2 and dopant surface, the production of activated oxygen radicals maybe used for elimination of toxic gases. The sensing mechanism of GY-Fe was discussed by desorption properties of gas and band structure analysis, we obtained the recovery time about 7.89 s for SO2 at 398 K. Therefore, this study, maybe provide some helpful informations for the design of graphyne-based gas sensors and catalysts.
