| 1. |
- Wang, Yanzhi, et al.
(författare)
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Anchoring Fe Species on the Highly Curved Surface of S and N Co-Doped Carbonaceous Nanosprings for Oxygen Electrocatalysis and a Flexible Zinc-Air Battery
- 2024
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Ingår i: Angewandte Chemie International Edition. - 1433-7851 .- 1521-3773. ; 63:7
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Tidskriftsartikel (refereegranskat)abstract
- Oxygen reduction reaction (ORR) is of critical significance in the advancement of fuel cells and zinc-air batteries. The iron-nitrogen (Fe−Nx) sites exhibited exceptional reactivity towards ORR. However, the task of designing and controlling the local structure of Fe species for high ORR activity and stability remains a challenge. Herein, we have achieved successful immobilization of Fe species onto the highly curved surface of S, N co-doped carbonaceous nanosprings (denoted as FeNS/Fe3C@CNS). The induction of this twisted configuration within FeNS/Fe3C@CNS arose from the assembly of chiral templates. For electrocatalytic ORR tests, FeNS/Fe3C@CNS exhibits a half-wave potential (E1/2) of 0.91 V in alkaline medium and a E1/2 of 0.78 V in acidic medium. The Fe single atoms and Fe3C nanoparticles are coexistent and play as active centers within FeNS/Fe3C@CNS. The highly curved surface, coupled with S substitution in the coordination layer, served to reduce the energy barrier for ORR, thereby enhancing the intrinsic catalytic activity of the Fe single-atom sites. We also assembled a wearable flexible Zn-air battery using FeNS/Fe3C@CNS as electrocatalysts. This work provides new insights into the construction of highly curved surfaces within carbon materials, offering high electrocatalytic efficacy and remarkable performance for flexible energy conversion devices.
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| 2. |
- Yang, Liting, et al.
(författare)
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Ligand-Directed Conformational Control over Porphyrinic Zirconium Metal-Organic Frameworks for Size-Selective Catalysis
- 2021
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 143:31, s. 12129-12137
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Tidskriftsartikel (refereegranskat)abstract
- Zirconium-based metal-organic frameworks (Zr-MOFs) have aroused enormous interest owing to their superior stability, flexible structures, and intriguing functions. Precise control over their crystalline structures, including topological structures, porosity, composition, and conformation, constitutes an important challenge to realize the tailor-made functionalization. In this work, we developed a new Zr-MOF (PCN-625) with a csq topological net, which is similar to that of the well-known PCN-222 and NU-1000. However, the significant difference lies in the conformation of porphyrin rings, which are vertical to the pore surfaces rather than in parallel. The resulting PCN-625 exhibits two types of one-dimensional channels with concrete diameters of 2.03 and 0.43 nm. Furthermore, the vertical porphyrins together with shrunken pore sizes could limit the accessibility of substrates to active centers in the framework. On the basis of the structural characteristics, PCN-625(Fe) can be utilized as an efficient heterogeneous catalyst for the size-selective [4 + 2] hetero-Diels-Alder cycloaddition reaction. Due to its high chemical stability, this catalyst can be repeatedly used over six times. This work demonstrates that Zr-MOFs can serve as tailor-made scaffolds with enhanced flexibility for target-oriented functions.
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| 3. |
- Yuan, Shuai, et al.
(författare)
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Continuous Variation of Lattice Dimensions and Pore Sizes in Metal-Organic Frameworks
- 2020
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 142:10, s. 4732-4738
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Tidskriftsartikel (refereegranskat)abstract
- The continuous variation of the lattice metric in metal-organic frameworks (MOFs) allows precise control over their chemical and physical properties. This has been realized herein by a series of mixed-linker and Zr-6-cluster-based MOFs, namely, continuously variable MOFs (CVMOFs). Similar to the substitutional solid solutions, organic linkers with different lengths and various ratios were homogeneously incorporated into a framework rather than being allowed to form separate phases or domains, which was manifested by single-crystal X-ray diffraction, powder X-ray diffraction, fluorescence quenching experiments, and molecular simulations. The unit cell dimension, surface area, and pore size of CVMOFs were precisely controlled by adopting different linker sets and linker ratios. We demonstrate that CVMOFs allow the continuous and fine tailoring of cell-edge lengths from 17.83 to 32.63 angstrom, Brunauer-Emmett-Teller (BET) surface areas from 585 to 3791 m(2)g(-1), and pore sizes up to 15.9 angstrom. Furthermore, this synthetic strategy can be applied to other MOF systems with various metal nodes thus allowing for a variety of CVMOFs with unprecedented tunability.
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| 4. |
- Abdelhamid, Hani Nasser, et al.
(författare)
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A Fast and Scalable Approach for Synthesis of Hierarchical Porous Zeolitic Imidazolate Frameworks and One-Pot Encapsulation of Target Molecules
- 2017
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 56:15, s. 9139-9146
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Tidskriftsartikel (refereegranskat)abstract
- A trimethylamine (TEA)-assisted synthesis approach that combines the preparation of hierarchical porous zeolitic imidazolate framework ZIF-8 nanoparticles and one-pot encapsulation of target molecules is presented. Two dye molecules, rhodamine B (RhB) and methylene blue (MB), and one protein (bovine serum albumin, BSA) were tested as the target molecules. The addition of TEA into the solution of zinc nitrate promoted the formation of ZnO nanocrystals, which rapidly transformed to ZIF-8 nanoparticles after the addition of the linker 2-methylimidazole (Hmim). Hierarchical porous dye@ZIF-8 nanoparticles with high crystallinity, large BET surface areas (1300–2500 m2/g), and large pore volumes (0.5–1.0 cm3/g) could be synthesized. The synthesis procedure was fast (down to 2 min) and scalable. The Hmim/Zn ratio could be greatly reduced (down to 2:1) compared to previously reported ones. The surface areas, and the mesopore size, structure, and density could be modified by changing the TEA or dye concentrations, or by postsynthetic treatment using reflux in methanol. This synthesis and one-pot encapsulation approach is simple and can be readily scaled up. The photophysical properties such as lifetime and photostability of the dyes could be tuned via encapsulation. The lifetimes of the encapsulated dyes were increased by 3–27-fold for RhB@ZIF-8 and by 20-fold for MB@ZIF-8, compared to those of the corresponding free dyes. The synthesis approach is general, which was successfully applied for encapsulation of protein BSA. It could also be extended for the synthesis of hierarchical porous cobalt-based ZIF (dye@ZIF-67).
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| 5. |
- Bao, Zijia, et al.
(författare)
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A bimetallic 3D interconnected metal–organic framework with 2D morphology and its derived electrocatalyst for oxygen reduction
- 2023
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Ingår i: CrystEngComm. - : Royal Society of Chemistry (RSC). - 1466-8033. ; 25:13, s. 1869-1873
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Tidskriftsartikel (refereegranskat)abstract
- Metal–organic frameworks (MOFs) are widely used as precursors to generate derivatives for electrocatalysis. However, two-dimensional (2D) MOFs often suffer from the collapse of their 2D structures after being treated at high temperature. Herein, we used the dense ZIF-EC1 as a precursor and doped Co as a secondary metal. The content of Co in ZIF-EC1 can be tuned without changing the crystalline structure. After pyrolysis, the derived carbon-based material maintains the 2D morphology from the parental precursor. The derived ZIF-EC1(ZnCo)-20-900 exhibits the best activity toward the ORR, which is even better than that of Pt/C. This work demonstrates the potential of using a nonporous dense MOF as a precursor and optimizing electrocatalytic ORR activity by tuning the Co content.
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| 6. |
- Bao, Zijia, et al.
(författare)
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A helical polypyrrole nanotube interwoven zeolitic imidazolate framework and its derivative as an oxygen electrocatalyst
- 2022
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; 58:80, s. 11288-11291
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Tidskriftsartikel (refereegranskat)abstract
- A helical polypyrrole nanotube interwoven zeolitic imidazolate framework (ZIF) has been prepared for the first time. After pyrolysis, the helical carbon could act as highly active sites, while the 3D-connected nanoarchitecture contributed to fast charge transfer. The derived carbon material exhibits high activity for the ORR and good performance for a Zn–air battery.
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| 7. |
- Brandner, Lea A., et al.
(författare)
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Water sensitivity of heteroepitaxial Cu-MOF films : dissolution and re-crystallization of 3D-oriented MOF superstructures
- 2023
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Ingår i: Chemical Science. - 2041-6520 .- 2041-6539. ; 14:43, s. 12056-12067
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Tidskriftsartikel (refereegranskat)abstract
- 3D-oriented metal–organic framework (MOF) films and patterns have recently emerged as promising platforms for sensing and photonic applications. These oriented polycrystalline materials are typically prepared by heteroepitaxial growth from aligned inorganic nanostructures and display anisotropic functional properties, such as guest molecule alignment and polarized fluorescence. However, to identify suitable conditions for the integration of these 3D-oriented MOF superstructures into functional devices, the effect of water (gaseous and liquid) on different frameworks should be determined. We note that the hydrolytic stability of these heteroepitaxially grown MOF films is currently unexplored. In this work, we present an in-depth analysis of the structural evolution of aligned 2D and 3D Cu-based MOFs grown from Cu(OH)2 coatings. Specifically, 3D-oriented Cu2L2 and Cu2L2DABCO films (L = 1,4-benzenedicarboxylate, BDC; biphenyl-4,4-dicarboxylate, BPDC; DABCO = 1,4-diazabicyclo[2.2.2]octane) were exposed to 50% relative humidity (RH), 80% RH and liquid water. The combined use of X-ray diffraction, infrared spectroscopy, and scanning electron microscopy shows that the sensitivity towards humid environments critically depends on the presence of the DABCO pillar ligand. While oriented films of 2D MOF layers stay intact upon exposure to all levels of humidity, hydrolysis of Cu2L2DABCO is observed. In addition, we report that in environments with high water content, 3D-oriented Cu2(BDC)2DABCO recrystallizes as 3D-oriented Cu2(BDC)2. The heteroepitaxial MOF-to-MOF transformation mechanism was studied with in situ synchrotron experiments, time-resolved AFM measurements, and electron diffraction. These findings provide valuable information on the stability of oriented MOF films for their application in functional devices and highlight the potential for the fabrication of 3D-oriented superstructures via MOF-to-MOF transformations.
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| 8. |
- Carmona, Francisco J., et al.
(författare)
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Coordination Modulation Method To Prepare New Metal-Organic Framework-Based CO-Releasing Materials
- 2018
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 10:37, s. 31158-31167
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Tidskriftsartikel (refereegranskat)abstract
- Aluminum-based metal organic frameworks (MOFs), [Al(OH)(SDC)](n), (H2SDC: 4,4'-stilbenedicarboxylic acid), also known as CYCU-3, were prepared by means of the coordination modulation method to produce materials with different crystal size and morphology. In particular, we screened several reagent concentrations (20-60 mM) and modulator/ligand ratios (0-50), leading to 20 CYCU x_y materials (x: reagent concentration, y = modulator/ligand ratio) with different particle size and morphology. Noteworthy, the use of high modulator/ligand ratio gives rise to a new phase of CYCU-3 (CYCU-3' x_50 series), which was structurally analyzed. Afterward, to test the potential of these materials as CO-prodrug carriers, we selected three of them to adsorb the photo- and bioactive CO-releasing molecule (CORM) ALF794 [Mo(CNCMe2CO2H)(3)(CO)(3)] (CNCMe2CO2H = 2-isocyano-2-methyl propionic acid): (i) CYCU-3 20_0, particles in the nanometric range; (ii) CYCU-3 50_5, bar-type particles with heterogeneous size, and (iii) CYCU-3' 50_50, a new phase analogous to pristine CYCU-3. The corresponding hybrid materials were fully characterized, revealing that CYCU-3 20_0 with the smallest particle size was not stable under the drug loading conditions. Regarding the other two materials, similar ALF794 loadings were found (0.20 and 0.19 CORM/MOF molar ratios for ALF794@CYCU-3 50_5 and ALF794@CYCU-3' 50_50, respectively). In addition, these hybrid systems behave as CO-releasing materials (CORMAs), retaining the photoactive properties of the pristine CORM in both phosphate saline solution and solid state. Finally, the metal leaching studies in solution confirmed that ALF794@CYCU-3' 50_50 shows a good retention capacity toward the potentially toxic molybdenum fragments (7S% of retention after 72 h), which is the lowest value reported for a MOF-based CORMA to date.
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| 9. |
- Carraro, F., et al.
(författare)
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Phase dependent encapsulation and release profile of ZIF-based biocomposites
- 2020
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Ingår i: Chemical Science. - : Royal Society of Chemistry (RSC). - 2041-6520 .- 2041-6539. ; 11:13, s. 3397-3404
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Tidskriftsartikel (refereegranskat)abstract
- Biocomposites composed of Zeolitic Imidazolate Frameworks (ZIFs) are generating significant interest due to their facile synthesis, and capacity to protect proteins from harsh environments. Here we systematically varied the composition (i.e. relative amounts of ligand (2-methylimidazole), metal precursor (Zn(OAc)(2)center dot 2H(2)O), and protein) and post synthetic treatments (i.e. washes with water or water/ethanol) to prepare a series of protein@ZIF biocomposites. These data were used to construct two ternary phase diagrams that showed the synthesis conditions employed gave rise to five different phases including, for the first time, biocomposites based on ZIF-CO3-1. We examined the influence of the different phases on two properties relevant to drug delivery applications: encapsulation efficiency and release profile. The encapsulation efficiencies of bovine serum albumin and insulin were phase dependent and ranged from 75% to 100%. In addition, release profiles showed that 100% protein release varied between 40 and 300 minutes depending on the phase. This study provides a detailed compositional map for the targeted preparation of ZIF-based biocomposites of specific phases and a tool for the straightforward analysis of the crystalline phases of ZIF based materials (web application named ZIF phase analysis). These data will facilitate the progress of ZIF bio-composites in the fields of biomedicine and biotechnology.
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| 10. |
- Chang, Ribooga, et al.
(författare)
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Achieving Molecular Sieving of CO2 from CH4 by Controlled Dynamical Movement and Host–Guest Interactions in Ultramicroporous VOFFIVE-1-Ni by Pillar Substitution
- 2024
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Ingår i: Nano Letters. - 1530-6984 .- 1530-6992. ; 24:25, s. 7616-
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Tidskriftsartikel (refereegranskat)abstract
- Engineering the building blocks in metal–organic materials is an effective strategy for tuning their dynamical properties and can affect their response to external guest molecules. Tailoring the interaction and diffusion of molecules into these structures is highly important, particularly for applications related to gas separation. Herein, we report a vanadium-based hybrid ultramicroporous material, VOFFIVE-1-Ni, with temperature-dependent dynamical properties and a strong affinity to effectively capture and separate carbon dioxide (CO2) from methane (CH4). VOFFIVE-1-Ni exhibits a CO2 uptake of 12.08 wt% (2.75 mmol g–1), a negligible CH4 uptake at 293 K (0.5 bar), and an excellent CO2-over-CH4 uptake ratio of 2280, far exceeding that of similar materials. The material also exhibits a favorable CO2 enthalpy of adsorption below −50 kJ mol–1, as well as fast CO2 adsorption rates (90% uptake reached within 20 s) that render the hydrolytically stable VOFFIVE-1-Ni a promising sorbent for applications such as biogas upgrading.
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