The application of conventional metal–organic frameworks (MOFs) as electrode materials in supercapacitors is largely hindered by their conventionally poor electrical conductivity. This study reports ...the fabrication of conductive MOF nanowire arrays (NWAs) and the application of them as the sole electrode material for solid‐state supercapacitors. By taking advantage of the nanostructure and making full use of the high porosity and excellent conductivity, the MOF NWAs in solid‐state supercapacitor show the highest areal capacitance and best rate performance of all reported MOF materials for supercapacitors, which is even comparable to most carbon materials.
Conductive metal–organic framework (MOF) nanowire arrays (NWAs) are prepared as the sole electrode material for solid‐state supercapacitors. By taking advantage of their nanostructure and making full use of the high porosity and excellent conductivity, the MOF NWAs in the solid‐state supercapacitor show the highest areal capacitance and best rate performance of all reported MOF materials.
The utility of electronically conductive metal–organic frameworks (EC‐MOFs) in high‐performance devices has been limited to date by a lack of high‐quality thin film. The controllable thin‐film ...fabrication of an EC‐MOF, Cu3(HHTP)2, (HHTP=2,3,6,7,10,11‐hexahydroxytriphenylene), by a spray layer‐by‐layer liquid‐phase epitaxial method is reported. The Cu3(HHTP)2 thin film can not only be precisely prepared with thickness increment of about 2 nm per growing cycle, but also shows a smooth surface, good crystallinity, and high orientation. The chemiresistor gas sensor based on this high‐quality thin film is one of the best room‐temperature sensors for NH3 among all reported sensors based on various materials.
A wafer‐thin sensor: The preparation of a crystalline, highly‐oriented, and thickness‐controlled thin film with an electronically conductive MOF is reported. Chemiresistive sensors based on these thin films show a high response, excellent selectivity, fast response speed, and good long‐term stability towards NH3 gas at room temperature.
Heterostructured metal—organic framework (MOF)‐on‐MOF thin films have the potential to cascade the various properties of different MOF layers in a sequence to produce functions that cannot be ...achieved by single MOF layers. An integration method that relies on van der Waals interactions, and which overcomes the lattice‐matching limits of reported methods, has been developed. The method deposits molecular sieving Cu‐TCPP (TCPP=5,10,15,20‐tetrakis(4‐carboxyphenyl)porphyrin) layers onto semiconductive Cu‐HHTP (HHTP=2,3,6,7,10,11‐hexahydrotriphenylene) layers to obtain highly oriented MOF‐on‐MOF thin films. For the first time, the properties in different MOF layers were cascaded in sequence to synergistically produce an enhanced device function. Cu‐TCPP‐on‐Cu‐HHTP demonstrated excellent selectivity and the highest response to benzene of the reported recoverable chemiresistive sensing materials that are active at room temperature. This method allows integration of MOFs with cascading properties into advanced functional materials.
MOF‐on‐MOF thin films were prepared from Cu‐HHTP (HHTP=hexahydrotriphenylene) and Cu‐TCPP (TCPP=tetrakis(4‐carboxyphenyl)porphyrin frameworks). The properties of the MOF layers cascade to produce functionality not achieved by a single layer. The MOF‐on‐MOF films demonstrate excellent selectivity and the highest response to benzene among reported recoverable chemiresistive sensing materials active at room temperature.
Arranging ionic liquids (ILs) with long‐range order can not only enhance their performance in a desired application, but can also help elucidate the vital between structure and properties. However, ...this is still a challenge and no example has been reported to date. Herein, we report a feasible strategy to achieve a crystalline IL via coordination self‐assembly based reticular chemistry. IL1MOF, was prepared by designing an IL bridging ligand and then connecting them with metal clusters. IL1MOF has a unique structure, where the IL ligands are arranged on a long‐range ordered framework but have a labile ionic center. This structure enables IL1MOF to break through the typical limitation where the solid ILs have lower proton conductivity than their counterpart bulk ILs. IL1MOF shows 2–4 orders of magnitude higher proton conductivity than its counterpart IL monomer across a wide temperature range. Moreover, by confining the IL within ultramicropores (<1 nm), IL1MOF suppresses the liquid–solid phase transition temperatures to lower than −150 °C, allowing it to function with high conductivity in a subzero temperature range.
A reticular chemistry based strategy opens a facile toolbox for designing liquid molecules with long‐rang‐ordered framework of MOF. IL1MOF is the first crystalline ionic liquid (IL) combining a balance of good mechanical properties and high conductivity. It expands the use of IL electrolytes to an low temperature region.
Under high temperature anhydrous conditions, it is still a formidable challenge to improve the performance of proton‐conducting materials based on H3PO4 and elucidate its proton conduction mechanism. ...Herein, a highly stable covalent triazine frameworks (CTFs) based on H3PO4 is reported. The more pyridinic nitrogen CTFs contain, the higher proton conductivity is. Compared with H3PO4@CTF−L with less pyridinic nitrogen, H3PO4@CTF−H has a higher proton conductivity of 1.6×10−1 S cm−1 at 150 °C under anhydrous conditions, which does not decay after about 18 months exposure in air. The high proton conductivity is associated with the formation and breaking of the activated Ntriazine⋯H+⋯H2PO4− pairs by pyridinic nitrogen of CTFs. The outstanding long‐term stability is mainly attributed to the ultra‐strong triazine skeleton structure of CTFs.
Flow of protons: The proton transport of H3PO4@CTFs relies on the reorganization of activated hydrogen bonds of H3PO4 by the alkaline pyridinic nitrogen under anhydrous conditions. H3PO4@CTFs is a very stable and high‐performance proton exchange membrane material.
Engineering the band gap chemically by organic molecules is a powerful tool with which to optimize the properties of inorganic 2D materials. The obtained materials are however still limited by ...inhomogeneous compositions and properties at nanoscale and small adjustable band gap ranges. To overcome these problems in the traditional exfoliation and then organic modification strategy, an organic modification and then exfoliation strategy was explored in this work for preparing 2D organic metal chalcogenides (OMCs). Unlike the reported organically modified 2D materials, the inorganic layers of OMCs are fully covered by long-range ordered organic functional groups. By changing the electron-donating ability of the organic functional groups and the electronegativity of the metals, the band gaps of OMCs were varied by 0.83 eV and their conductivities were modulated by 9 orders of magnitude, which are 2 and 10
times higher than the highest values observed in the reported chemical methods, respectively.
A novel sulfonate–carboxylate ligand of biphenyl-3,3′-disulfonyl-4,4′-dicarboxylic acid (H4–BPDSDC) and its lanthanide–organic frameworks {LnK(BPDSDC)(DMF)(H2O)·x(solvent)} n (JXNU-2, where JXNU ...denotes Jiangxi Normal University, DMF indicates dimethylformamide, and Ln = Sm3+, Eu3+, and Pr3+) were synthesized and structurally characterized. The three isomorphous lanthanide compounds feature three-dimensional frameworks constructed from one-dimensional (1D) rod-shaped heterometallic Ln–K secondary building units and are an illustration of a Kagome-like lattice with large 1D hexagonal channels and small 1D trigonal channels. The porous material of the representive JXNU-2(Sm) has an affinity to quadrupolar molecules such as CO2 and C2H2. In addition, the JXNU-2(Sm) compound exhibits humidity- and temperature-dependent proton conductivity with a large value of 1.11 × 10–3 S cm–1 at 80 °C and 98% relative humidity. The hydrophilic sulfonate group on the surface of channels facilitates enrichment of the solvate water molecules in the channels, which enhances the proton conductivity of this material. Moreover, the JXNU-2(Eu) material with the characteristic bright red color shows the potential for recognition of K+ and Fe3+ ions. The enhancing Eu3+ luminescence with the K+ ion and quenching Eu3+ luminescence with the Fe3+ ion can be associated with the functional groups of the organic ligand.
The layer‐by‐layer liquid‐phase epitaxy (LBL‐LPE) method is widely used in preparing metal–organic framework (MOF) thin films with the merits of controlling thickness and out‐of‐plane orientation for ...superior performances in applications. The LBL‐LPE growth mechanism related to the grain boundary, structure defect, and orientation is critical but very challenging to study. In this work, a novel “in‐plane self‐limiting and self‐repairing” thin‐film growth mechanism is demonstrated by the combination study of the grain boundary, structure defect, and orientation of Cu3(HHTP)2‐xC thin film via microscopic analysis techniques and electrical measurements. This mechanism results a desired high‐quality MOF thin film with preferred in‐plane orientations at its bottom for the first time and is very helpful for optimizing the LBL‐LPE method, understanding the growth cycle‐dependent properties of MOF thin film, and inspiring the investigations of the biomimetic self‐repairing materials.
A novel in‐plane self‐limited and self‐repairing growth mechanism was demonstrated for the preparation of LBL‐LPE thin films. The method provides a high‐quality MOF thin film with preferred in‐plane orientation at its bottom part.
To develop proton‐conducting materials under low‐humidity conditions and at moderate working temperature still remains challenging for fuel‐cell technology. Here, a new type of proton‐conducting ...material, EIMS‐HTFSA@MIL, which was prepared by impregnating the binary ionic liquid, EIMS‐HTFSA (EIMS=1‐(1‐ethyl‐3‐imidazolium)propane‐3‐sulfonate; HTFSA=N,N‐bis(trifluoromethanesulfonyl)amide), into a mesoporous metal–organic framework, MIL‐101 (Cr3F(H2O)2O(BDC)3⋅n H2O (n≈0.25, BDC=1,4‐benzenedicarboxylate)) is reported. By taking advantage of the ionic‐liquid properties, such as high thermal stability, non‐volatility, non‐flammability, and low corrosivity, EIMS‐HTFSA@MIL shows potential application as a safe electrolyte in proton conduction above 100 °C.
Ionic liquid makes it conduct: A binary ionic liquid was rationally designed and facilely impregnated into a MOF support to construct an anhydrous proton conductor with high conductivity above 100 °C, which opens a new way up to achieve novel anhydrous PEMs materials with high performance and low safety hazards at moderate temperature.
Network structures based on Star‐of‐David catenanes with multiple superior functionalities have been so far elusive, although numerous topologically interesting networks are synthesized. Here, a ...metal–organic framework featuring fused Star‐of‐David catenanes is reported. Two triangular metallacycles with opposite handedness are triply intertwined forming a Star‐of‐David catenane. Each catenane fuses with its six neighbors to generate a porous twofold intercatenated gyroid framework. The compound possesses exceptional stability and exhibits multiple functionalities including highly selective CO2 capture, high proton conductivity, and coexistence of slow magnetic relaxation and long‐range ordering.
A metal–organic framework, which represents the rare networks composed of Star‐of‐David catenanes, is designed. The structural complexity of the unique framework highlights different facets of the same compound. Remarkably, the material shows highly selective CO2 capture for a molecular‐sieving effect, superionic proton conductivity, and coexistence of slow magnetic relaxation and long‐range ordering.
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