A diaminotriazine-decorated porphyrin-based microporous hydrogen-bonded organic framework has been successfully prepared and characterized using single crystal X-ray diffraction analysis. Its ...activated phase exhibits permanent porosity, gas separation, and proton conductivity under humid conditions.
Perovskite oxides are star materials due to their particularly rich properties such as superconductivity, ferroelectricity, magnetic property, and photocatalytic activity. A recent study Ji, D. ...Freestanding crystalline oxide perovskites down to the monolayer limit. Nature 2019, 570, 87 90 showed that freestanding two-dimensional (2D) perovskite oxides down to the monolayer limit can prepared. The intrinsic nanoscale of 2D perovskite oxides may impart them more intriguing properties and more possibility for their application in nanoscale electronic and spintronic devices. Taking SrTiO3 as an example, we investigate the impact of dimension reduction from three-dimension (3D) to 2D on the thermodynamic and electronic properties of perovskite oxides. We find that the thermodynamic stability of 2D structures is termination-dependent. Moreover, 2D SrTiO3, regardless of terminations (SrO- or TiO2-, or both), exhibit abnormal band-gap trends, with a gap value lower than the bulk limit, suggesting an unusual quantum size effect in 2D SrTiO3. The origin of abnormal trends can be attributed to the band splitting of conduction bands and surface states of valence bands. Our results provide a clear picture about the evolution of the electronic properties of materials with the change of dimension in perovskite oxides.
A series of structurally related rigid imidazole ligands, 1,4-bis(imidazol-1-yl)benzene (L 1 ), 1,4-bis(benzoimidazol-1-yl)benzene (L 2 ), and 4,4′-bis(benzoimidazol-1-yl)biphenyl (L 3 ), have been ...utilized to construct coordination polymers. The reactions of CdX2 (X = BF4 − or ClO4 −) with these ligands afford three new three-dimensional networks, {Cd(L 1 )3(BF4)2(CHCl3)2}∞ (1), {Cd(L 2 )3(ClO4)2(CHCl3)4(CH3OH)2}∞ (2), and {Cd(L 3 )3(ClO4)2}∞ (3). Compounds 1−3 are all α-Po metal−organic frameworks (MOFs) based on six-connected CdII nodes which are octahedrally coordinated by six nitrogen atoms of ligand molecules. Complex 2 represents a distorted α-Po framework with noninterpenetration, whereas 1 and 3 both exhibit a double interpenetrating α-Po network. These results suggest that the degree of interpenetration is tunable by ligand modifications, that is, varying the ligand spacer or terminal group. The three complexes exhibit a different void volume in their network. Gas adsorption measurements indicate that 3 possesses moderate gas-adsorption ability for CO2, and the progress of adsorption and desorption is reversible.
Metal–organic frameworks (MOFs) with diverse structures, adjustable pore sizes, and high surface areas have exhibited awesome potential in many fields. Here we report a simple carbonization strategy ...to obtain a series of core–shell structured Co/Co3O4 nanoparticles encapsulated into nitrogen-doped carbon shells from cobalt-based metal–organic framework precursors at different carbonization temperatures. When it is applied as an anodes for lithium ion batteries, the Co/Co3O4@N-C-700 electrode delivers a maximum initial discharge capacity of 1535 mAh g–1, the highest reversible capacity (903 mAh g–1 at a current density of 100 mA g–1 after 100 cycles), and the best rate performance (i.e., 774 mAh g–1 at a current density of 1.0 A g–1 after 100 cycles) in comparison with those of Co/Co3O4@N-C-600 and Co/Co3O4@N-C-800 electrodes. The excellent electrochemical performance could be mainly attributed to the unique core–shell structure, abundant graphited carbon, and the well-dispersed Co/Co3O4 nanoparticles which can promote the specific capacity through conversion reactions.
Selective-adsorption separation is an energy-efficient technology for the capture of acetylene (C2H2) from carbon dioxide (CO2) and ethylene (C2H4). However, it remains a critical challenge to ...effectively recognize C2H2 among CO2 and C2H4, owing to their analogous molecule sizes and physical properties. Herein, we report a new microporous metal–organic framework (NUM-14) possessing a carefully tailored pore system containing moderate pore size and nitro-functionalized channel surface for efficient separation of C2H2 from CO2 and C2H4. The activated NUM-14 (namely NUM-14a) exhibits sufficient pore space to acquire excellent C2H2 loading capacity (4.44 mmol g−1) under ambient conditions. In addition, it possesses dense nitro groups, acting as hydrogen bond acceptors, to selectively identify C2H2 molecules rather than CO2 and C2H4. The breakthrough experiments demonstrate the good actual separation ability of NUM-14a for C2H2/CO2 and C2H2/C2H4 mixtures. Furthermore, Grand Canonical Monte Carlo simulations indicate that the pore surface of the NUM-14a has a stronger affinity to preferentially bind C2H2 over CO2 and C2H4 via stronger C-H···O hydrogen bond interactions. This article provides some insights into customizing pore systems with desirable pore sizes and modifying groups in terms of MOF materials toward the capture of C2H2 from CO2 and C2H4 to promote the development of more MOF materials with excellent properties for gas adsorption and separation.
A novel robust three-dimensional octahedral-like caged metal-organic framework with ultrahigh selectivities has been demonstrated to exhibit the potential for purification of methane in nearly pure ...form from a 6-component gas mixture at room temperature.
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•An ultramicroporous MOF based on octahedral-like cages with dual functionalities was successfully designed and constructed.•The elaborate pore size/confinement made the MOF has high adsorption capacities and strong affinities for C2/C3 hydrocarbons.•The MOF represents high selectivities for C2/CH4 and C3/CH4 mixtures.•One-step CH4 purification from a highly complex six-component C1/C2/C3 hydrocarbons mixture was realized using the MOF.
Given the crucial significance of using cleaner methane (CH4) to replace else fossil fuels in remitting energy consumption and preventing environmental degradation, developing prominent adsorbents to purify CH4 from multicomponent mixtures is fundamentally important but faces great challenges. Cage-based metal-organic frameworks (MOFs) bring about widespread attention in solving numerous separation problems due to their inherent structural preponderances. Herein, we constructed an octahedral-like cages-based MOF (NUM-18) that incorporates two different types of cages within the whole framework and bears abundant Lewis basic sites (naked N atoms) and nonpolar aromatic rings immobilized in the pore surface. Benefitting from its intriguing structural characteristics, the pure-component gas adsorption properties were systematically investigated and indicate that NUN-18a (activated NUM-18) has excellent adsorptive capacities with respect to C2-C3 hydrocarbons than CH4. The IAST adsorption selectivities for C2/CH4 are above 14.0, while the adsorption selectivities of C3/CH4 startlingly surpass 86.0, respectively, all of which forebode that NUM-18a can achieve efficient recovery of C2-C3 hydrocarbons associated with CH4 purification. Furthermore, the actual separation feasibility for an equimolar 6-component C1/C2/C3 hydrocarbons mixture was examined by simulated dynamic column breakthrough experiments. Finally, molecular simulation calculations were adopted to ascertain potential gas adsorption mechanisms. This work provided a new paradigm for developing novel porous crystalline MOFs materials to separate hyper-complex gas mixtures.
A sulfur and nitrogen containing cobalt metal‐organic framework (Co−MOF) was chosen as a precursor to prepare cobalt sulfides as HER electrocatalysts. Cobalt sulfides with different stoichiometries, ...CoS1.097, Co9S8, Co9S8/CoS1.097, and Co9S8/CoS1.097/rGO, were obtained through a phase control method and in‐situ sulfuration of the MOF precursor. Co9S8/CoS1.097/rGO shows excellent HER performance, with an overpotential of 50 mV at a current density (j) of 1 mA cm−2 (η0), and 188 mV at a current density of 10 mA cm−2 (η10), stemming from the synergistic effect of Co9S8, CoS1.097, high specific surface area and the nitrogen and sulfur doped carbon matrix.
In phase: different cobalt sulfides, CoS1.097, Co9S8, Co9S8/CoS1.097 and Co9S8/CoS1.097/rGO, are obtained following a phase control method and in‐situ sulfuration of a S, N‐containing Co based metal‐organic framework. Co9S8/CoS1.097/rGO shows excellent HER performance of 50 mV at a current density (j) of 1 mA cm−2 (η0), and 188 mV at a current density of 10 mA cm−2 (η10), stemming from the co‐effect of Co9S8, CoS1.097, high specific surface area and the N and S doped C matrix.
Preparation of the high value-added chemical 2,5-dimethylfuran (2,5-DMF) from the biomass-derived platform molecule 5-hydroxymethylfurfural (HMF) is of great significance in the preparation of ...biofuels. Here, a bottom-up strategy was used to prepare a metal-organic framework (MOF) material with a two-dimensional nanosheet morphology, named CPM, in which an additive 2-methylimidazole was introduced into the hydrothermal process of Cu
2+
ions and terephthalic acid. Subsequently, CPM-700 prepared by heat treatment under an inert atmosphere showed excellent catalytic performance in the reaction of HMF hydrodeoxygenation to 2,5-DMF. The materials before and after pyrogenation were characterized by PXRD, XPS, TEM, N
2
adsorption and desorption and so on. It was confirmed that compared with the catalyst derived from the cubic MOF material self-assembled by Cu
2+
and terephthalic acid, the morphology of 2D nanosheets was beneficial for the reaction of HMF to 2,5-DMF. Combined with the experimental data, the possible reaction path of 2,5-DMF preparation from HMF is that 2,5-dihydroxymethylfuran was formed by hydrogenation of the aldehyde group on the furan ring, and then 2,5-DMF was obtained by hydrogenolysis. This paper provides an effective route for 2D MOF-derived catalytic materials in the selective hydrogenation of HMF.
A bottom-up strategy was used to prepare an MOF-based catalytic material with a two-dimensional nanosheet morphology, in which 2-methylimidazole was the additive. It is of great significance in the preparation of 2,5-dimethylfuran from 5-hydroxymethylfurfural.
We constructed a robust microporous metal-organic framework (MUM-15) possessing two types of functionalized tri-mural nanotraps, in which elaborate nano-space and specific pore environment are ...beneficial to form pore confinement effect and multiple strong interactions for C2H2. NUM-15 demonstrates not only remarkable sorption capacity for C2H2 but also exhibits excellent separation performance for intractable C2H2/CO2 and C2H2/C2H4 mixtures.
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•The strategy for constructing nanotraps was proposed and a novel MOF was successfully designed and synthesized.•The tailor-made tri-mural nanotraps provided pore confinement and synergetic multiple interaction sites for C2H2.•Both high uptake capacity and strong affinity for C2H2 were realized.•The MOF exhibits excellent separation ability for C2H2/CO2 and C2H2/C2H4 mixtures under ambient conditions.
Considering the tremendous significance of purification and capture for acetylene (C2H2) in the fields of manufacturing and the petrochemical industry, seeking appropriate materials with prominent performance is a crucial task and also remains an enduring challenge. To pursue this target, we report a robust microporous metal-organic framework (NUM-15) featuring two types of elaborate tri-mural nanotraps, in which fruitful nano-space confinement for accommodating gas molecules and multiple preferential adsorption sites providing multiple specific interactions with C2H2 were supplied to form cooperative effect for efficient separation property. The NUM-15a (activated NUM-15) exhibits high loading for C2H2 (3.5 mmol g−1) over carbon dioxide (CO2) and ethylene (C2H4) at 298 K and 1.0 bar and shows efficient separation performance for binary C2H2/CO2 and C2H2/C2H4 mixtures. The GCMC calculation revealed the crucial role of the multiple interactions in nanotraps for the selective capture of C2H2. Under ambient conditions, dynamic breakthrough experiments revealed that NUM-15a demonstrates the enormous potential for actual industrial gas separation and is expected to be applied to the correlative industrial process. Both experiments and simulation calculations distinctly demonstrated that fabricating tri-mural nanotraps in MOFs is a feasible strategy for efficient C2H2 capture and separation and provided a new route for exploiting high-performance materials for separation and purification technology.
