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The importance of substituting fossil fuels with clean and renewable energies, and the introduction of hydrogen as a promising option in this field is one of the most popular challenges for researchers. Here, we performed the spin-polarized DFT calculations to investigate the ability of the hydrogen adsorption and storage of modified graphdiyne (GDY) by B and N atoms (BN-GDY) under positive and negative external electric fields. Our findings show that the BN-GDY nanosheet has a weak interaction with the H2 molecule in absence of the electric field, and the electric field can effectively improve this interaction and increase the adsorption energy of the H2 molecule on the BN-GDY nanosheet. Also, the negative electric field has more effect relative to the positive one, and with increasing the intensity of the electric field, the adsorption energy has an upward trend. At the highest intensities of positive and negative applied fields (±0.046 V/Å), the BN-GDY nanosheet can store up to 4 and 8H2 molecules with the average adsorption energies of ?0.253 and ?0.258 eV/H2, and the H2 storage capacity can reach up to 3.59 and 6.93 wt%, respectively. The preference of our work for practical application is the free metal promotion of H2 adsorption and storage.  相似文献   
2.
Ammonia synthesis by electrochemical nitrogen reduction technique is an attractive alternative to tradi-tional Haber-Bosch process.Currently,development of an efficient and effective electrocatalyst is one of the remaining key challenges.In this work,density functional theory(DFT)computations were systemat-ically employed on double transition metal atoms(Fe,Co,Ni,Cu and Mo)anchored Graphdiyne(GDY)for nitrogen reduction reaction(NRR).The Co-Ni heteronuclear complex and Mo-Mo homonuclear complex showed the highest NRR activity while demonstrating synergistic effect of double atomic catalytic sites towards the promising NRR activity.  相似文献   
3.
The acetylenic carbon-rich nanostructures such as graphdiyne has been received increasing attentions due to its potential applications in energy conversion, photoelectronic devices, catalysis, sensing and biomedical areas. So, development of facile synthesis procedures for ultrathin graphdiyne nanostructures is a challenge. Here, a prompt and simple method is proposed for polycondensation of 1,3,5-triethynylbenezene and synthesis of graphdiyne-like nanosheets, using bipolar electrochemistry assisted by copper grid electrode in the ethanol/acetonitrile solvent. The large scale of graphdiyne can be achieved with a series of bipolar electrodes in a single bipolar cell. The prepared nanosheets are characterized by various techniques, such as SEM, TEM, Raman and XPS. The as prepared material shows a remarkable photocatalytic activity toward hydrogen evolution (25 μA cm?2 at 0.6 V vs. RHE) as well as oxygen evolution (4.5 μA cm?2 at 1.1 V vs. RHE) activity at low overpotentials. The proposed method promised as a rapid and simple process for synthesis of graphdiyne-like nanostructures with remarkable electrocatalytic activity at less than 150 min. Furthermore, the presented procedure can be developed as applicable method for preparation of other grphdiyne-like nanostructures for fabrication of sensing and biosensing devices, optical imaging and nanoparticles loading.  相似文献   
4.
Developing economical electrocatalysts as alternatives to platinum for oxygen reduction reaction (ORR) to develop the applications of green energy devices like proton exchange membrane fuel cells (PEMFCs) is of paramount importance. In the current study, a different ratio of nitrogen-doped graphdiyne (GDY) with Fe single-site is reported to be more cost-effective and efficient for PEMFCs. The current study also demonstrates the design principle to improve the ORR activity associated with catalysts using Fe single-site with a greater Fe charge, which is controlled through the coordinated structure of the active center. Based on the simulation results, the formation of N2-doped GDY and N2-doepd Fe-GDY are more lucrative compared to the formation of Nx-doped GDY (x > 2) in terms of energy. O2 molecules have a direct dissociation on the N2-doepd Fe-GDY via Eley-Rideal (ER) mechanism, which involves the formation of H2O by reacting with H+ from the electrolyte. Moreover, N2-doepd Fe-GDY exhibits better performance as an ORR catalyst in an acidic medium because of its low overpotential of 0.488 V. However, N2-doped GDY follows the OOH1 formation pathway, showing a higher overpotential for ORR. Furthermore, in the structure under study, the thermodynamic favorability of ORR is observed since the reaction energies calculated at each reaction step are exothermic and the energy profile of all reaction steps are downhill. The results of the current work provide new insights into the construction of extremely efficient heterogeneous catalysts in electrochemical energy technologies.  相似文献   
5.
CO2 reduction (CO2RR) and hydrogen evolution reactions (HER) are widely used in advanced energy conversion systems, which are urgently required low-cost and high efficient electrocatalysts to overcome the sluggish reaction kinetic and ultralow selectivity. Here, the single-, double-, and triple-atomic Cu embedded graphdiyne (Cu1-3@GDY) complexes have been systematically modeled by first-principles computations to evaluate the corresponding electric structures and catalytic performance. The results revealed that these Cu1-3@GDY monolayers possess high thermal stability by forming the firm Cu–C bonds. The Cu1-3@GDY complexes exhibit good electrical conductivity, which could promote the charge transfer in the electroreduction process. The electronic and magnetic interactions between key species (1H, 1COOH, and 1OCHO) and Cu1-3@GDY complexes are responsible for the different catalytic performance of HER and CO2RR on different Cu1-3@GDY sheets. The Cu2@GDY complex could efficiently convert CO2 to CH4 with a rather low limiting potential of ?0.42 V due to the spin magnetism of catalysts. The Cu1@GDY and Cu3@GDY exhibit excellent HER catalytic performance, and their limiting potentials are ?0.18 and ?0.02 V, respectively. Our findings not only provide a valuable avenue for the design of atomic metal catalysts toward various catalytic reactions but also highlight an important role of spin magnetism in electrocatalysts.  相似文献   
6.
本文基于密度泛函理论,研究了二维碳材料石墨烯和石墨炔的电子结构和光学性质。计算结果表明石墨烯比石墨炔更稳定,在费米能级附近它们的电子态主要由C-2p态贡献;石墨烯在可见光区域是透明的并且表现出良好的非线性光学吸收特性和电导率;石墨炔的光吸收和光电导对长波下的可见光响应明显,在费米能级附近的电子跃迁,除了从价带到导带的跃迁外还存在带间跃迁。本文的结论可为二维碳材料石墨烯和石墨炔在光电器件、光催化等领域中的应用提供理论依据。  相似文献   
7.
Separation of hydrogen from gases mixtures is of great interest as hydrogen energy is among the most promising renewable energies. Graphdiyne shows huge potential as membrane for gas separation due to its uniform pore and atomic-scale thickness. In this work, hydrogen separation performance of graphdiyne, B-doped graphdiyne and BN-doped graphdiyne membranes are evaluated through first principles and molecular dynamics calculations. It is revealed that the selectivity of BN-doped graphdiyne to H2 is much greater than those of graphdiyne and B-doped graphdiyne in this study and that of N-doped graphdiyne reported in previous work. The permeance of H2 for the BN-doped graphdiyne membrane exceeds the industrial production limit at various temperatures. A high separation efficiency of H2 can be achieved by reducing temperature below 275, 225 and 390 K for graphdiyne, B-doped graphdiyne and BN-doped graphdiyne membranes, respectively. Therefore, BN-doped graphdiyne is a prospective membrane for highly selective hydrogen separation at room temperature, and it is also demonstrated by molecular dynamics simulations of permeation process. This study provides an effective approach to evaluate selectivity and permeance of graphdiyne-based membranes for gases separation.  相似文献   
8.
Graphdiyne (GDY) is a new member of carbon allotropes consisting of sp and sp2 hybridized carbon atoms. In this work, the hydrogen adsorption on Calcium (Ca) decorated GDY and the influence of adatom on structural properties of GDY are investigated, using first principles plane wave calculations with Van der Waals corrections. The results show that similar to graphyne (GY) and unlike carbon nanotube (CNT), fullerene and graphene, clustering of Ca on GDY hinders due to the higher binding energy of the adatom to the carbon frame than the Ca cohesive energy. It can be seen that the Ca-decoration promotes hydrogen storage capacity of GDY, extremely (Eads = ?0.266 and ?0.066 eV for Ca-decorated and pristine GDY, respectively). It is concluded that, the best site for the Ca trapping is 18-membered ring in which, Ca lies in-plane of GDY (Eads = ?3.171 eV). Fourteen H2 molecules (with the average adsorption energy of ~0.2 eV/H2) can be adsorbed on the Ca atom from one side. The hydrogen storage capacity is estimated to be as high as 17.95 wt% for the both sides of GDY. So, the Ca-decorated GDY is offered as a promising candidate for hydrogen storage applications.  相似文献   
9.
Tensile strain of porous membrane materials can broaden their capacity in gas separation. In this work, using van der Waals corrected density functional theory(DFT) and molecular dynamics(MD) simulations, the performance and mechanism of CO_2/CH_4 separation through strain-oriented graphdiyne(GDY) monolayer were studied by applying lateral strain. It is demonstrated that the CO_2 permeance peaks at 1.29 × 10~6 gas permeation units(GPU) accompanied with CO_2/CH_4 selectivity of 5.27 × 10~3 under ultimate strain, both of which are far beyond the Robeson's limit. Furthermore, the GDY membrane exhibited a decreasing gas diffusion energy barrier and increasing permeance with the increase of applied tensile strain. CO_2 molecule tends to reoriented itself vertically to permeate the membrane. Finally, the CO_2 permeability decreases with the increase of the temperature from300 K to 500 K due to conserving of rotational freedom, suggesting an abnormal permeance of CO_2 in relation to temperature. Our theoretical results suggest that the stretchable GDY monolayer holds great promise to be an excellent candidate for CO_2/CH_4 separation, owing to its extremely high selectivity and permeability of CO_2.  相似文献   
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