| 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. |
- 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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| 3. |
- Chen, Gan, et al.
(författare)
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Effects of Transition Metals on Metal–Octaaminophthalocyanine-Based 2D Metal–Organic Frameworks
- 2023
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Ingår i: ACS Nano. - 1936-0851 .- 1936-086X. ; 17:10, s. 9611-9621
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Tidskriftsartikel (refereegranskat)abstract
- Metal–octaaminophthalocyanine (MOAPc)-based 2D conductive metal–organic frameworks (cMOFs) have shown great potential in several applications, including sensing, energy storage, and electrocatalysis, due to their bimetallic characteristics. Here, we report a detailed metal substitution study on a family of isostructural cMOFs with Co2+, Ni2+, and Cu2+ as both the metal nodes and the metal centers in the MOAPc ligands. We observed that different metal nodes had variations in the reaction kinetics, particle sizes, and crystallinities. Importantly, the electronic structure and conductivity were found to be dependent on both types of metal sites in the 2D cMOFs. Ni-NiOAPc was found to be the most conductive one among the nine possible combinations with a conductivity of 54 ± 4.8 mS/cm. DFT calculations revealed that monolayer Ni-NiOAPc has neither the smallest bandgap nor the highest charge carrier mobility. Hence its highest conductivity stems from its high crystallinity. Collectively, these results provide structure property relationships for MOAPc-based cMOFs with amino coordination units.
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| 4. |
- Jaradat, Ahmad, et al.
(författare)
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A High-Rate Li–CO2 Battery Enabled by 2D Medium-Entropy Catalyst
- 2023
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Ingår i: Advanced Functional Materials. - 1616-301X .- 1616-3028. ; 33:21
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Tidskriftsartikel (refereegranskat)abstract
- Lithium-air batteries based on CO2 reactant (Li–CO2) have recently been of interest because it has been found that reversible Li/CO2 electrochemistry is feasible. In this study, a new medium-entropy cathode catalyst, (NbTa)0.5BiS3, that enables the reversible electrochemistry to operate at high rates is presented. This medium entropy cathode catalyst is combined with an ionic liquid-based electrolyte blend to give a Li–CO2 battery that operates at high current density of 5000 mA g−1 and capacity of 5000 mAh g−1 for up to 125 cycles, far exceeding reported values in the literature for this type of battery. The higher rate performance is believed to be due to the greater stability of the multi-element (NbTa)0.5BiS3 catalyst because of its higher entropy compared to previously used catalysts with a smaller number of elements with lower entropies. Evidence for this comes from computational studies giving very low surface energies (high surface stability) for (NbTa)0.5BiS3 and transmission electron microscopystudies showing the structure being retained after cycling. In addition, the calculations indicate that Nb-terminated surface promotes Li–CO2 electrochemistry resulting in Li2CO3 and carbon formation, consistent with the products found in the cell. These results open new direction to design and develop high-performance Li–CO2 batteries.
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| 5. |
- Lv, Zhong-Peng, et al.
(författare)
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Visualizing noncovalent interactions and property prediction of submicron-sized charge-transfer crystals from ab-initio determined structures
- 2024
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Ingår i: Small Methods. - 2366-9608.
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Tidskriftsartikel (refereegranskat)abstract
- The charge-transfer (CT) interactions between organic compounds are reflected in the (opto)electronic properties. Determining and visualizing crystal structures of CT complexes are essential for the design of functional materials with desirable properties. Complexes of pyranine (PYR), methyl viologen (MV), and their derivatives are the most studied water-based CT complexes. Nevertheless, very few crystal structures of CT complexes have been reported so far. In this study, the structures of two PYRs-MVs CT crystals and a map of the noncovalent interactions using 3D electron diffraction (3DED) are reported. Physical properties, e.g., band structure, conductivity, and electronic spectra of the CT complexes and their crystals are investigated and compared with a range of methods, including solid and liquid state spectroscopies and highly accurate quantum chemical calculations based on density functional theory (DFT). The combination of 3DED, spectroscopy, and DFT calculation can provide important insight into the structure-property relationship of crystalline CT materials, especially for submicrometer-sized crystals.
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| 6. |
- Maliuta, Mariia, et al.
(författare)
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Flexibility in DUT-8(Cu) Metal–Organic Framework : Impact of Cluster, Stress, History, and Hierarchical Texture
- 2023
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Ingår i: CCS Chemistry. - 2096-5745. ; 5:10, s. 2225-2236
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Tidskriftsartikel (refereegranskat)abstract
- The flexibility of metal–organic frameworks (MOFs) featuring stimuli-responsive structural transitions is often governed not only by the chemical composition and topology but also by orthogonal factors such as particle size, desolvation method, and history of the sample. A precise understanding of the mechanism behind such observations has been lacking up to now, and there are still substantial open questions concerning the impact of sample treatment history. The DUT-8(M) family ([M2(2,6-ndc)2(dabco)]n, 2,6-ndc = 2,6-naphthalene dicarboxylate, dabco = 1,4-diazabicyclo-[2.2.2]-octane), encompasses isostructural compounds based on Ni, Zn, Co, and Cu in the cluster node and is representative of pillared layer MOFs, often showing flexible behavior. In this contribution, we discuss a possible explanation for the differences in flexibility observed in desolvated phases of DUT-8(Cu). Theoretical calculations and crystallographic data shed light on the preferred formation of interpenetrated confined closed pore phases in DUT-8(Cu) in contrast to DUT-8(Ni, Co, Zn) where the closed pore phases are formed.
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| 7. |
- Prasad, Ram R. R., et al.
(författare)
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Modulated Self-Assembly of Catalytically Active Metal-Organic Nanosheets Containing Zr6 Clusters and Dicarboxylate Ligands
- 2024
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Ingår i: ACS Applied Materials and Interfaces. - 1944-8244 .- 1944-8252. ; 16:14, s. 17812-17820
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Tidskriftsartikel (refereegranskat)abstract
- Two-dimensional metal–organic nanosheets (MONs) have emerged as attractive alternatives to their three-dimensional metal–organic framework (MOF) counterparts for heterogeneous catalysis due to their greater external surface areas and higher accessibility of catalytically active sites. Zr MONs are particularly prized because of their chemical stability and high Lewis and Brønsted acidities of the Zr clusters. Herein, we show that careful control over modulated self-assembly and exfoliation conditions allows the isolation of the first example of a two-dimensional nanosheet wherein Zr6 clusters are linked by dicarboxylate ligands. The hxl topology MOF, termed GUF-14 (GUF = Glasgow University Framework), can be exfoliated into monolayer thickness hns topology MONs, and acid-induced removal of capping modulator units yields MONs with enhanced catalytic activity toward the formation of imines and the hydrolysis of an organophosphate nerve agent mimic. The discovery of GUF-14 serves as a valuable example of the undiscovered MOF/MON structural diversity extant in established metal–ligand systems that can be accessed by harnessing the power of modulated self-assembly protocols.
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| 8. |
- Wang, Shuxi, et al.
(författare)
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Thermodynamics and Kinetics in Anisotropic Growth of One-Dimensional Midentropy Nanoribbons
- 2023
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Ingår i: ACS Nano. - 1936-0851 .- 1936-086X. ; 17:15, s. 15053-15064
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Tidskriftsartikel (refereegranskat)abstract
- One-dimensional (1D) materials demonstrate anisotropic in-plane physical properties that enable a wide range of functionalities in electronics, photonics, valleytronics, optoelectronics, and catalysis. Here, we undertake an in-depth study of the growth mechanism for equimolar midentropy alloy of (NbTaTi)0.33S3 nanoribbons as a model system for 1D transition metal trichalcogenide structures. To understand the thermodynamic and kinetic effects in the growth process, the energetically preferred phases at different synthesis temperatures and times are investigated, and the phase evolution is inspected at a sequence of growth steps. It is uncovered that the dynamics of the growth process occurs at four different stages via preferential incorporation of chemical species at high-surface-energy facets. Also, a sequence of temperature and time dependent nonuniform to uniform phase evolutions has emerged in the composition and structure of (NbTaTi)0.33S3 which is described based on an anisotropic vapor–solid (V–S) mechanism. Furthermore, direct evidence for the 3D structure of the charge density wave (CDW) phase (width less than 100 nm) is provided by three-dimensional electron diffraction (3DED) in individual nanoribbons at cryogenic temperature, and detailed comparisons are made between the phases obtained before and after CDW transformation. This study provides important fundamental information for the design and synthesis of future 1D alloy structures.
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| 9. |
- Zhang, Chengji, et al.
(författare)
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Lithium superoxide-based high rate Li-Air batteries enabled by Di-iridium sulfur bridge active sites
- 2023
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Ingår i: Energy Storage Materials. - 2405-8289 .- 2405-8297. ; 60
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Tidskriftsartikel (refereegranskat)abstract
- Li-oxygen (Li-O2) batteries can potentially provide much higher energy density than Li-ion batteries; however, the practical application of these batteries is hindered due to several drawbacks such as low current rates and high overpotential for the charging process. In this paper, we report a novel Li-Air battery system that operates under high current rates (up to 1mAcm 2) with LiO2 as the primary discharge product instead of the commonly reported Li2O2. This LiO2 based battery at high rates is through a combination of an as-synthesized new onedimensional (1D) transition metal trichalcogenide mid-entropy alloy of SnIrS3.6 as a cathode catalyst and an electrolyte blend with a SnI2 bi-functional additive. It is revealed that SnIrS3.6 has a microporous structure composed of six- and five-coordinated metal atoms, forming octahedral and triangular bipyramids which has not been observed in other layered chalcogeide materials. DFT calculations reveal that the SnIrS3.6 structure can result in LiO2 formation through di-iridium sulfur bridge active sites that results in strong binding of O2 and LiO2 preventing disproportionation to Li2O2 and enabling high rates. This finding will open a new perspective in designing advanced LiO2-based Li-O2 batteries for real practices.
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| 10. |
- Zhang, Jianjun, et al.
(författare)
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Wavy Two-Dimensional Conjugated Metal-Organic Framework with Metallic Charge Transport
- 2023
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Ingår i: Journal of the American Chemical Society. - 0002-7863 .- 1520-5126. ; 145:43, s. 23630-23638
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Tidskriftsartikel (refereegranskat)abstract
- Two-dimensional conjugated metal–organic frameworks (2D c-MOFs) have emerged as a new class of crystalline layered conducting materials that hold significant promise for applications in electronics and spintronics. However, current 2D c-MOFs are mainly made from organic planar ligands, whereas layered 2D c-MOFs constructed by curved or twisted ligands featuring novel orbital structures and electronic states remain less developed. Herein, we report a Cu-catecholate wavy 2D c-MOF (Cu3(HFcHBC)2) based on a fluorinated core-twisted contorted hexahydroxy-hexa-cata-hexabenzocoronene (HFcHBC) ligand. We show that the resulting film is composed of rod-like single crystals with lengths up to ∼4 μm. The crystal structure is resolved by high-resolution transmission electron microscopy (HRTEM) and continuous rotation electron diffraction (cRED), indicating a wavy honeycomb lattice with AA-eclipsed stacking. Cu3(HFcHBC)2 is predicted to be metallic based on theoretical calculation, while the crystalline film sample with numerous grain boundaries apparently exhibits semiconducting behavior at the macroscopic scale, characterized by obvious thermally activated conductivity. Temperature-dependent electrical conductivity measurements on the isolated single-crystal devices indeed demonstrate the metallic nature of Cu3(HFcHBC)2, with a very weak thermally activated transport behavior and a room-temperature conductivity of 5.2 S cm–1. Furthermore, the 2D c-MOFs can be utilized as potential electrode materials for energy storage, which display decent capacity (163.3 F g–1) and excellent cyclability in an aqueous 5 M LiCl electrolyte. Our work demonstrates that wavy 2D c-MOF using contorted ligands are capable of intrinsic metallic transport, marking the emergence of new conductive MOFs for electronic and energy applications.
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