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.
Metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) are important members of crystalline porous materials due to their huge structural diversity and tunability. By hybridizing MOFs ...or COFs with other materials, restrictions of the pristine materials, i.e., poor conductivity and weak mechanical property, can be effectively circumvented. This review summarizes several hybridization techniques from the molecular level to the micro‐ and macroscales for the preparation of various MOF and COF hybrids. Then, their representative applications as electrochemical energy storage devices are elaborated, such as rechargeable batteries, supercapacitors, polymer electrolytes, and separators. The basic principles and mechanisms for guiding hybridization are also properly clarified.
Crystalline porous materials (CPMs) (metal–organic frameworks and covalent organic frameworks) hybrids and their applications in electrochemical energy storage systems (EES) are reviewed. Hybridization strategies and methods are explained from three dimensions: molecular‐, nano/microscopic‐, and macroscopic‐levels. Combined with the application of CPMs in EES, the significance and purpose of hybridization are elaborated in detail.
A strategy for combining metal oxides and metal–organic frameworks is proposed to design new materials for sensing volatile organic compounds, for the first time. The prepared ZnO@ZIF‐CoZn ...core–sheath nanowire arrays show greatly enhanced performance not only on its selectivity but also on its response, recovery behavior, and working temperature.
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.
Single‐ligand‐based electronically conductive porous coordination polymers/metal–organic frameworks (EC‐PCPs/MOFs) fail to meet the requirements of numerous electronic applications owing to their ...limited tunability in terms of both conductivity and topology. In this study, a new 2D π‐conjugated EC‐MOF containing copper units with mixed trigonal ligands was developed: Cu3(HHTP)(THQ) (HHTP=2,3,6,7,10,11‐hexahydrotriphenylene, THQ=tetrahydroxy‐1,4‐quinone). The modulated conductivity (σ≈2.53×10−5 S cm−1 with an activation energy of 0.30 eV) and high porosity (ca. 441.2 m2 g−1) of the Cu3(HHTP)(THQ) semiconductive nanowires provided an appropriate resistance baseline and highly accessible areas for the development of an excellent chemiresistive gas sensor.
Makes sense: As two ligands offer more opportunity than one to tune MOF conductivity and topology, a 2D π‐conjugated copper‐based electronically conductive MOF with two different trigonal organic ligands was developed (see structure). The semiconductivity and high porosity of the resulting nanowires provided a low conductivity baseline and highly accessible surface areas, thus resulting in excellent room‐temperature chemiresistive sensing properties.
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.
Exploring new porous coordination polymers (PCPs) that have tunable structure and conductivity is attractive but remains challenging. Herein, fine pore structure engineering by ligand conformation ...control of naphthalene diimide (NDI)‐based semiconducting PCPs with π stacking‐dependent conductivity tunability is achieved. The π stacking distances and ligand conformation in these isoreticular PCPs were modulated by employing metal centers with different coordination geometries. As a result, three conjugated PCPs (Co−pyNDI, Ni−pyNDI, and Zn−pyNDI) with varying pore structure and conductivity were obtained. Their crystal structures were determined by three‐dimensional electron diffraction. The through‐space charge transfer and tunable pore structure in these PCPs result in modulated selectivity and sensitivity in gas sensing. Zn−pyNDI can serve as a room‐temperature operable chemiresistive sensor selective to acetone.
Conjugated 3D naphthalene diimide (NDI) based conductive porous coordination polymers (PCPs) with tunable conductivity and pore structure are developed as chemiresistors for room‐temperature gas sensors. The Zn−pyNDI can serve as a room‐temperature operable chemiresistive sensor selective to acetone.
Electrically conductive metal–organic frameworks (cMOFs) have garnered significant attention in materials science due to their potential applications in modern electrical devices. However, achieving ...effective modulation of their conductivity has proven to be a major challenge. In this study, we have successfully prepared cMOFs with high conductivity by incorporating electron‐donating fused thiophen rings in the frameworks and extending their π‐conjugated systems through ring‐closing reactions. The conductivity of cMOFs can be precisely modulated ranging from 10−3 to 102 S m−1 by regulating their dimensions and topologies. Furthermore, leveraging the inherent tunable electrical properties based on topology, we successfully demonstrated the potential of these materials as chemiresistive gas sensors with an outstanding response toward 100 ppm NH3 at room temperature. This work not only provides valuable insights into the design of functional cMOFs with different topologies but also enriches the cMOF family with exceptional conductivity properties.
Highly conductive metal–organic frameworks (cMOFs) are formed by incorporating electron‐donating fused thiophene rings into their frameworks and extending their π‐conjugated systems. The conductivity can be modulated by adjusting the solvent system, thus regulating the dimensions and topologies of the cMOFs. 1D Cu‐MOF‐1 can be easily processed into thin membranes. The 2D kgm‐Cu‐MOF‐3 has an excellent response toward NH3 at room temperature.
The construction of hydrophobic nanochannel with hydrophilic sites for bionic devices to proximally mimick real bio‐system is still challenging. Taking the advantages of MOF chemistry, a highly ...oriented CuTCPP thin film has been successfully reconstructed with ultra‐thin nanosheets to produce abundant two‐dimensional interstitial hydrophobic nanochannels with hydrophilic sites. Different from the classical active‐layer material with proton transport in bulk, CuTCPP thin film represents a new type of active‐layer with proton transport in nanochannel for bionic proton field‐effect transistor (H+‐FETs). The resultant device can reversibly modulate the proton transport by varying the voltage on its gate electrode. Meanwhile, it shows the highest proton mobility of ≈9.5×10−3 cm2 V−1 s−1 and highest on‐off ratio of 4.1 among all of the reported H+‐FETs. Our result demonstrates a powerful material design strategy for proximally mimicking the structure and properties of bio‐systems and constructing bionic electrical devices.
A MOF thin film‐based bionic proton field‐effect transistor (H+‐FET) has been fabricated for the first time. It displays the highest proton mobility and highest on–off ratio among all reported H+‐FETs.
Superlattice materials offer new opportunities to modify optical and electrical properties of recently emerging 2D materials. The insertion of tetraethylbenzidine (EtDAB) into interlamination of the ...established 2D PbI2 semiconductor through a mild solution method yielded the first lead iodide superlattice, EtDAB⋅4PbI2 (EtDAB=tetraethylbenzidine), with radical and non‐radical forms. The non‐radical form has a non‐ionic structure that differs from the common ionic structures for inorganic–organic hybrid lead halides. The radical form shows five orders of magnitude greater conductance and broader photoconductive response range (UV/Vis → UV/Vis‐IR), than pure PbI2 and the non‐radical form of the superlattice.
Lead the way: The first lead‐iodide superlattice constructed from non‐ionic organic molecules and PbI2 through van der Waals interactions is a new type of inorganic–organic hybrid and has a radical and a non‐radical form. The radical form has an almost five orders of magnitude greater conductivity and broader band photoconductive response than that of the non‐radical form or pure PbI2.
