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1.
This paper aimed to study the effects of fullerene (C60) impregnation on the isoreticular metal-organic framework (IRMOF) materials MOF-650 (ZnO4 nodes were connected to azulenedicarboxylate linkers), MOF-5(ZnO4 nodes were connected to benzenedicarboxylate linkers), and IRMOF-10 (ZnO4 nodes were connected to biphenyldicarboxylate linkers) for H2 storage, these IRMOFs had similar structures but different pore volumes and organic linkers. Density functional theory (DFT) and grand canonical monte Carlo (GCMC) calculations indicated that C60 plays an important role in balancing the gravimetric and volumetric H2 densities of the IRMOFs. The C60@IRMOFs revealed improved volumetric density when H2 was undersaturated but reduced gravimetric density under H2 saturation. The saturated gravimetric H2 density of the IRMOFs was decided by the free volume. At 77 K, C60@MOF-650 had a gravimetric H2 density of 5.3 wt% and volumetric H2 density of 42 g/L under 10 bar, and C60@IRMOF-10 had a gravimetric H2 density of 7.4 wt% and volumetric H2 density of 43 g/L under 18 bar. These values nearly meet the United States Department of Energy (DOE) gravimetric and volumetric H2 density ultimate targets (gravimetric H2 density, 6.5 wt%; volumetric H2 density, 50  g/L) under ambient pressures. Among the studied IRMOFs, C60@MOF-650 and C60@IRMOF-10 demonstrated the best H2 storage properties at 233 and 298 K.  相似文献   

2.
Combined density functional theory and grand canonical monte Carlo (GCMC) calculations were performed to study the electronic structures and hydrogen adsorption properties of the Zn-based metal-organic framework MOF-650. The benzene azulenedicarboxylate linkers of MOF-650 were substituted by B atoms, N atoms, and boronic acid B(OH)2 linkers, and the Zn atoms were substituted by Mg and Ca atoms. The calculated electronic densities of states (DOSs) of MOF-650 showed that introduction of B atoms reduces the band gap but damages the structure of MOF-650. Introduction of single N bonds cannot provide active electrons to attract H2 molecules. Thus, substitutions of B and N into MOF-650 are not suggested. B(OH)2 substitute in MOF-650 decreased its band gap, slightly improved its hydrogen storage ability and made H2 molecules more intensively distributed besides organic linkers. GCMC calculations were carried out by estimating the H2 storage amount of the pure and modified MOFs at 77 and 298 K and from 1 bar to 20 bar. B(OH)2 linker and Mg/Ca co-doped MOF-650 showed increased H2 adsorption by approximately 20 wt%. The adsorption of H2 around different bonds showed the order N–C < C = C < B–C < C–O < B–O.  相似文献   

3.
Based on the first-principles derived force fields and grand canonical Monte Carlo simulations, we find that the catenated metal-organic frameworks outperform the noncatenated structures, in terms of H2 separation from other gases (CH4, CO and CO2) and H2 adsorption by Li doping. A system utilizing IRMOF-11 (or IRMOF-13) for hydrogen separation and Li-doped IRMOF-9 for hydrogen storage is therefore proposed, with hydrogen uptake of 4.91 wt% and 36.6 g/L at 243 K and 100 bar for Li-doped IRMOF-9, which is close to the 2017 DOE target. It is promising to find appropriate microporous materials for hydrogen purification and storage at ambient conditions with structure catenated.  相似文献   

4.
Metal-organic frameworks (MOFs) exhibiting high surface area and tunable pore size own broad application prospects. Compared with existing MOFs, MOF-5 [Zn4O(bdc)3] is a promising hydrogen storage material due to high H2 uptake capacity and thermostability. However, further wider applications of MOF-5 have been limited because atmospheric moisture levels cause MOF-5 instability. MOF-5 and multi-walled carbon nanotubes (MWCNTs) hybrid composite (denoted MOFMC) can enhance stability toward ambient moisture and improve hydrogen storage capacity. In this paper, the MOFMC, which has an interpenetrated structure with high mesoporosity, was synthesized. The MOFMC is denoted as Int-MOFMC-meso. It stored 2.02 wt% H2 at 77 K under 1 bar, which is higher than the MOF-5 with similar structure and the earlier reported MOFMC material. Moreover, the Int-MOFMC-meso can also show more excellent performance of thermostability and moisture stability than the MOF-5 with similar structure.  相似文献   

5.
The adsorption of hydrogen molecules on monolayer graphene is investigated using molecular dynamics simulations (MDS). Interatomic interactions of the graphene layer are described using the well-known AIREBO potential, while the interactions between graphene and hydrogen molecule are described using Lennard-Jones potential. In particular, the effect of strain and different point defects on the hydrogen storage capability of graphene is studied. The strained graphene layer is found to be more active for hydrogen and show 6.28 wt% of H2 storage at 0.1 strain at 77 K temperature and 10 bar pressure. We also studied the effect of temperature and pressure on the adsorption energy and gravimetric density of H2 on graphene. We considered different point defects in the graphene layer like monovacancy (MV), Stone Wales (SW), 5-8-5 double vacancy (DV), 555–777 DV, and 5555-6-7777 DV which usually occur during the synthesis of graphene. At 100 bar pressure, graphene with 1% concentration of MV defects leads to 9.3 wt% and 2.208 wt% of H2 storage at 77 K and 300 K, respectively, which is about 42% higher than the adsorption capacity of pristine graphene. Impact of defects on the critical stress and strain of defected graphene layers is also studied.  相似文献   

6.
In this work, adsorption of H2 molecules on heteroborospherene C2v C4B32 decorated by alkali atoms (Li) is studied by density functional theory calculations. The interaction between Li atoms and C4B32 is found to be strong, so that it prevents agglomeration of the former. An introduced hydrogen molecule tilts toward the Li atoms and is stably adsorbed on C4B32. It is obtained that Li4C4B32 can store up to 12H2 molecules with hydrogen uptake capacity of 5.425 wt% and average adsorption energy of ?0.240 eV per H2. Dynamics simulation results show that 6H2 molecules can be successfully released at 300 K. Obtained results demonstrate that Li decorated C4B32 is a promising material for reversible hydrogen storage.  相似文献   

7.
Two strategies of decoration by three elements Z = Li, Be and Na in cyclic site, and substitution of Zn by Mg and Cd in unit cell were used in the framework of functional density theory to tune the hydrogen storage properties of metal-organic framework-5 (MOF-5) based on Zn whose decomposition temperature and initial gravimetric capacity are 300 K and 1.57 wt% respectively.Based on the adsorption of hydrogen molecules in the crystal surface at three different adsorption sites with three orientations of H2, we show that our system may reach a maximum gravimetric storage capacity of 4.09 wt% for multiple hydrogen molecules. Moreover, the functionalization of Z combined to the substitution, shows an exceptional improvement of hydrogen storage properties. For example, Mg-MOF-5 decorated with Li2 has a capacity up to 5.41 wt% and 513 K as desorption temperature.  相似文献   

8.
The feasibility of transition metal coated fullerene cages M12C48B12(M = Fe, Co, and Ni) for hydrogen storage is investigated by the pseudopotential density functional theory. Fe12C48B12(Co12C48B12 and Ni12C48B12) adsorbs 60(48 and 48) H2 with moderate average adsorption energy of 0.50(0.45 and 0.32) eV/H2. The gravimetric hydrogen density of Fe12C48B12(Co12C48B12 and Ni12C48B12) can reach 8.7(6.8 and 6.8) wt%. The Dewar–Kubas interaction dominates the adsorption of H2 on the outer surface of Fe12C48B12(Co12C48B12 and Ni12C48B12). Therefore, the stable M12C48B12(M = Fe, Co, and Ni) cages can be applied as candidates for hydrogen storage under near-ambient conditions.  相似文献   

9.
The metal-organic framework Zn4O (BDC)3 (BDC = 1,4-bezene dicarboxlate), also known as MOF-5, has demonstrated considerable adsorption of hydrogen, up to 7 excess wt.% at 77 K. Consequently, it has attracted significant attention for vehicular hydrogen storage applications. To improve the volumetric hydrogen density and thermal conductivity of MOF-5, prior studies have examined the hydrogen storage capacities of dense MOF-5 pellets and the impact of thermally conductive additives such as expanded natural graphite (ENG). However, the performance of a storage system based on densified MOF-5 powders will also hinge upon the rate of hydrogen mass transport through the storage medium. In this study, we further characterize MOF-5 compacts by measuring their hydrogen transport properties as a function of pellet density (ρ = 0.3–0.5 g cm−3) and the presence/absence of ENG additions. More specifically, the Darcy permeability and diffusivity of hydrogen in pellets of neat MOF-5, and composite pellets consisting of MOF-5 with 5 and 10 wt.% ENG additions, have been measured at ambient (296 K) and liquid nitrogen (77 K) temperatures. The experimental data suggest that the H2 transport in densified MOF-5 is strongly related to the MOF-5 pellet density ρ.  相似文献   

10.
We report a density functional theory calculation dedicated to analyze the behavior of hydrogen adsorption on Yttrium-decorated C48B12. Electron deficient C48B12 is found to promote charge transfer between Y atom and substrate leading to an enhanced local electric field which can significantly improve the hydrogen adsorption. The analysis shows that Y atoms can be individually adsorbed on the pentagonal sites without clustering of the metal atoms, and each Y atom can bind up to six H2. molecules with an average binding energy of −0.46 eV/H2, which is suitable for ambient condition hydrogen storage. The Y atoms are found to trap H2 molecules through well-known “Kubas-type” interaction. Our simulations not only clarify the mechanism of the reaction among C48. B12, Y atoms and H2 molecules, but also predict a promising candidate for hydrogen storage application with high gravimetric density (7.51%).  相似文献   

11.
We report on an easy synthesis method for the preparation of a hybrid composite of Pt-loaded MWCNTs@MOF-5 [Zn4O(benzene-1,4-dicarboxylate)3] that greatly enhanced hydrogen storage capacity at room temperature. To prepare the composite, we first prepared Pt-loaded MWCNTs, which were then incorporated in-situ into the MOF-5 crystals. The obtained composite was characterized by various techniques such as powder X-ray diffractometry, optical microscopy, porosimetry by nitrogen adsorption, and hydrogen adsorption. The analyses confirmed that the product has a highly crystalline structure with a Langmuir specific surface area of over 2000 m2/g. The hybrid composite was shown to have a hydrogen storage capacity of 1.25 wt% at room temperature and 100 bar, and 1.89 wt% at cryogenic temperature and 1 bar. These H2 storage capacities represent significant increases over those of virgin MOF-5s and Pt-loaded MWCNTs.  相似文献   

12.
Using a deposition-reduction method, Mg/MOF nanocomposites were prepared as composites of Mg and metal-organic framework materials (MOFs = ZIF-8, ZIF-67 and MOF-74). The addition of MOFs can enhance the hydrogen storage properties of Mg. For example, within 5000 s, 0.6 wt%, 1.2 wt%, 2.7 wt%, 3.7 wt% of hydrogen were released from Mg, Mg/MOF-74, Mg/ZIF-8, Mg/ZIF-67, respectively. Activation energy values of 198.9 kJ mol−1 H2, 161.7 kJ mol−1 H2, 192.1 kJ mol−1 H2 were determined for the Mg/ZIF-8, Mg/ZIF-67, Mg/MOF-74 hydrides, which are 6 kJ mol−1 H2, 43.2 kJ mol−1 H2, and 12.8 kJ mol−1 H2 lower than that of Mg hydride, respectively. Moreover, the cyclic stability characterizing Mg hydride was significantly improved when adding ZIF-67. The hydrogen storage capacity of the Mg/ZIF-67 nanocomposite remained unchanged, even after 100 cycles of hydrogenation/dehydrogenation. This excellent cyclic stability may have resulted from the core-shell structure of the Mg/ZIF-67 nanocomposite.  相似文献   

13.
Doping heteroatoms and producing defects are perfect methods to improve the hydrogen storage property of TM-decorated carbon materials. In this view, four novel Sc/Ti-decorated and B- substituted defective C60 fullerenes (B24C24) are explored. The special stability, large specific surface, uniform distribution of the metal and positively charged states make these four fullerenes have high hydrogen storage capacities. Especially, each Sc atom in Sc6B24C24(B4) can adsorb up to five H2 molecules with a storage capacity of 6.80 wt %. The adsorbed H2 molecules in Sc6B24C24(B4)–30H2 begin to relax at 190 K and are 100% released at 290 K. Moreover, a comparative study is carried out for hydrogen storage properties of Sc-decorated B4, C4, or N4 coordination environments. These results provide a new focus on the nature of B-, and N-substituted defective carbon nanomaterials.  相似文献   

14.
The design and synthesis of new hydrogen storage materials with high capacity are the prerequisite for extensive hydrogen energy application which can be achieved by multi-site hydrogen storage. Herein, a Mg@C60 nano-lamellae structure with multiple hydrogen storage sites has been prepared through a simple ball-milling process in which Mg nanoparticles (∼5 nm) are homogeneously dispersed on C60 nano-lamellae. The as-obtained C60/Mg nano-lamellae displays an excess hydrogen uptake of 12.50 wt% at 45 bar, which is far higher than the theoretical value (7.60 wt%) of metal Mg and the US Department of Energy (DOE) target (5.50 wt%, 2020 year), also the experimental values reported by now. The enhanced hydrogen storage mainly comes from several storage sites: MgH2, Hx–C60 (CH chemical bonding), H2@C60 (the endohedral H2 in C60). Interestingly, the hybridization of Mg and C60 not only facilitate the dissociation of H2 molecules to form CH bonding with C60, but also promote the deformation of C60 and access H2 molecules into the cavity of C60. This work provides new insight into the underlying chemistry behind the high hydrogen storage capacities of a new class of hydrogen storage materials, fullerene/alkaline-earth metals nanocomposites.  相似文献   

15.
The B6Be2 and B8Be2 clusters, adopting fascinating inverse sandwich-like geometries, were recently predicted with quantum chemical calculations. Both systems exhibit the high stability and double aromaticity with 4σ/6π or 6σ/6π delocalized electrons. The hydrogen storage of two systems is studied in the present paper. Our calculations show that B6Be2 and B8Be2 clusters have the ultra-high capacity hydrogen storage, each Be site can bound up with seven H2 molecules, corresponding to a gravimetric density of 25.3 wt percentage (wt%) for B6Be2 and 21.1 wt% for B8Be2, respectively, which far exceeds the target (5.5 wt%) proposed by the US department of energy (DOE) in 2017. The average absorption energies of 0.10–0.45 eV/H2 for B6Be2 and 0.11–0.50 eV/H2 for B8Be2 at the wB97XD level suggest that both systems are ideal for reversible hydrogen storage and release. The reversibility of H2 molecules on B6Be2 and B8Be2 complexes are faithfully demonstrated with the Born-Oppenheimer molecular dynamics (BOMD) simulations. The Be-doped boron nanostructure is a promising candidate for ultra-high hydrogen storage materials.  相似文献   

16.
Employing first-principles calculations, we have studied the structure, stability and hydrogen storage efficiency of pristine and defective BC3 and C3N monolayer functionalized by a variety of single metal adatoms. It is found that single Sc adatom, acting as an optimal dopant on perfect BC3 monolayer, is able to adsorb up to nine H2 molecules as strongly as around 0.24 eV/H2, which allows for a hydrogen storage capacity of 7.19 wt% for Sc atoms stably adsorbing on double sides of BC3 monolayer with eighteen H2 molecules (18H2@2Sc/BC3). Moreover, the desorption temperature and thermodynamical stability of multiple H2 adsorbed Sc-decorated BC3 sheet have been addressed and the saturate configuration of 18H2@2Sc/BC3 is predicted to be stable at mild temperatures and pressures, i.e. less than 250 K at 1 bar, or larger than 24 bar at room temperature. This study indicates that the Sc-decorated BC3 monolayer could be a potential H2 storage candidate, and provides an instructive guidance for designing metal-functionalized carbon-based sheets in hydrogen storage.  相似文献   

17.
In this work, we prepared platinum doped on activated carbons/metal-organic frameworks-5 hybrid composites (Pt-ACs-MOF-5) to obtain a high hydrogen storage capacity. The surface functional groups and surface charges were confirmed by Fourier transfer infrared spectroscopy (FT-IR) and zeta-potential measurement, respectively. The microstructures were characterized by X-ray diffraction (XRD). The sizes and morphological structures were also evaluated using a scanning electron microscopy (SEM). The pore structure and specific surface area were analyzed by N2/77 K adsorption/desorption isotherms. The hydrogen storage capacity was studied by BEL-HP at 298 K and 100 bar. The results revealed that the hydrogen storage capacity of the Pt-ACs-MOF-5 was 2.3 wt.% at 298 K and 100 bar, which is remarkably enhanced by a factor of above five times and above three times compared with raw ACs and MOF-5, respectively. In conclusion, it was confirmed that Pt particles played a major role in improving the hydrogen storage capacity; MOF-5 would be a significantly encouraging material for a hydrogen storage medium as a receptor.  相似文献   

18.
We investigate the use of carbonized bamboo, which has an organic porous structure, as a hydrogen storage material. Bamboo samples were thermally treated at 800, 900, 1000, and 1100 °C for 24 h. The pore size and hydrogen storage capacity of each sample were measured by N2 and H2 gas sorption up to 1.13 bar at 77 K. The maximum hydrogen storage was exhibited by the sample treated at 900 °C, which reached 1.35 wt% at 1.13 bar/77 K. The results showed that the bamboo, one of the green carbons, has the potential to be used as an environmental-friendly carbon backbone for hybrid hydrogen storage materials.  相似文献   

19.
Li-Mg-N-H systems have been focused on as one of the most promising hydrogen storage systems owing to their high hydrogen contents and binary nitride, LiMgN, has a high gravimetric storage density of 8.2 wt% H2. We synthesized LiMgN by a hydriding thermal reaction between Mg and LiNH2 under various H2 pressures and a subsequent dehydrogenation reaction, and optimized conditions for the formation of pure LiMgN. The results demonstrate that pure LiMgN can be produced using hydriding thermal synthesis at 80 bar H2 pressure and 723 K. The hydriding and dehydriding characteristics of as-synthesized LiMgN were investigated by a Sievers’ type instrument. The reaction product LiMgN can be rehydrogenated by reacting with H2 under 80 bar of hydrogen pressure at 573 K, and then released under less than 0.5 bar at 573 K. The measured H2 capacity is about 6.8 wt% during the hydrogenation process.  相似文献   

20.
The hydrogen storage (H-storage) capacity of various boranes and alanes have been investigated using density functional theory (DFT) based M05-2X method employing 6–31+G** basis set. The changes in the H-storage capacities of borane and alane upon substitution of antipodal atoms in the cages by C, Si, and N have also been investigated. It is found from the calculations that a maximum of 20 H2 molecules can be adsorbed on the deltahedron faces of these cages. The maximum gravimetric density has been observed for boranes when compared to alanes. The H-storage capacity of closo-borane dianion [B12H12]2−, monocarborane [CB11H12]1−, dicarborane [C2B10H12], and closo-azaborane [NB11H12] cages is almost similar (∼22 wt.%). Among these cages, BBB dianion show higher binding energy (BE) and BE per H2 molecule (BE/nH2) which are 181.06 and 9.03 kJ/mol, respectively. In the case of alanes, dicarbalane [C2Al10H12] has maximum H-storage capacity of 11.6 wt.%. Based on these findings, a new MOF with carborane (MOF-5CC) as linker has been designed. The calculation on the new MOF-5BCC reveals that it has H-storage capacity of 6.4 wt.% with BE/nH2 of 3.02 kJ/mol.  相似文献   

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