Metal–Organic Frameworks as Metal Ion Precursors for the Synthesis of Nanocomposites for Lithium-Ion Batteries

Metal–organic frameworks (MOFs) are promising materials with fascinating properties. Their widespread applications are sometimes hindered by the intrinsic instability of frameworks. However, this instability of MOFs can also be exploited for useful purposes. Herein, we report the use of MOFs as metal ion precursors for constructing functional nanocomposites by utilizing the instability of MOFs. The heterogeneous growth process of nanostructures on substrates involves the release of metal ions, nucleation on substrates, and formation of a covering structure. Specifically, the synthesized CoS with carbon nanotubes as substrates display enhanced performance in a lithium-ion battery. Such strategy not only presents a new way for exploiting the instability of MOFs but also supplies a prospect for designing versatile functional nanocomposites.     

金属-有机框架应用于锂离子电池的研究进展

综述了金属-有机框架应用于锂离子电池的研究进展。金属-有机框架在锂离子电池中的应用主要有以下两个方面:1)用作锂电负极材料;2)用作锂电正极材料。同时总结了金属-有机框架做锂电电极材料存在的问题,并提出解决的可能途径。最后,展望了金属-有机框架在储能领域中的应用前景。     

Recent advances in metal-organic frameworks for lithium metal anode protection

The lithium metal battery has been considered as a promising candidate for next generation batteries.However,safety concerns caused by uncontrollable lithium dendrite growth on lithium anode are severely hampering the commercial application.Metal-organic frameworks(MOFs)become one of the most attractive materials due to the high porosity,structural designability and tunability.With unique open channels and pores as well as functional components in MOFs,the transportation and deposition of lithium ions can be regulated,which leads to enhanced electrochemical prope rties.Various strategies for lithium metal protection are proposed in recent wo rks on applications of MOFs in lithium metal batteries.In this review,we highlight latest key approaches in this field and discuss the prospects for MOFs in advanced Li anodes.     

Atomically Dispersed Metal Sites in MOF‐Based Materials for Electrocatalytic and Photocatalytic Energy Conversion

Metal sites play an essential role in both electrocatalytic and photocatalytic energy conversion. The highly ordered arrangements of the organic linkers and metal nodes as well as the well‐defined pore structures of metal‐organic frameworks (MOFs) make them ideal substrates to support atomically dispersed metal sites (ADMSs) located in their metal nodes, linkers, and pores. Porous carbon materials doped with ADMSs can be derived from these ADMS‐incorporating MOF precursors through controlled treatments. These ADMSs incorporated in pristine MOFs and MOF‐derived carbon materials possess unique advantages over molecular or bulk metal‐based catalysts and bridge the gap between homogeneous and heterogeneous catalysts for energy‐conversion applications. This Review presents recent progress in the design and incorporation of ADMSs in MOFs and MOF‐derived materials for energy‐conversion applications.     

金属有机骨架材料在金属锂电池界面的应用

金属锂电池是下一代高能量密度电池体系的代表。然而,高比能金属锂电池的发展受到界面诸多问题的限制,如:金属锂负极枝晶生长、隔膜界面兼容性、正极界面不稳定等,影响了金属锂电池的界面传质传荷过程,并导致金属锂界面环境恶化、电池的容量衰减、安全性能下降等问题。金属有机骨架(MOF)是一种具有稳定多孔结构的有机无机杂化材料,近年来在高比能金属锂电池领域受到广泛关注。其多孔结构与开放的金属位点(OMs)提供了优异的离子电导率,稳定的空间结构提供了较高的机械强度,多样的官能团与金属节点带来丰富的功能性。本文分析了金属锂电池界面的主要挑战,结合金属锂界面的成核模型,总结了MOF及其衍生材料在解决锂金属负极界面、隔膜界面、以及正负极界面稳定性相互作用等方面的研究进展和作用机理,为解决高比能金属锂电池界面失稳问题提供了解决途径,并展望了MOF基材料的设计与发展方向。     

Porous metal-organic frameworks as platforms for functional applications

Metal-organic frameworks (MOFs), also known as coordination polymers, have emerged as a new class of crystalline porous materials, which are constructed from metal ions or metal ion clusters and bridging organic linkers. MOFs have tunable pores and functionalities, and usually exhibit very high surface areas. The potential applications of porous MOFs cover a broad range of fields and most of their applications are related to pore sizes, shapes and structures/environments. In this feature article, we provide an overview of the recent developments of porous MOFs as platforms in the functional applications of sorption and separation, heterogeneous catalysis, as supports/host matrices for metal nanoparticles, and as templates/nanoreactors for new material preparation.     

Metalloporphyrin-Based Metal–Organic Frameworks on Flexible Carbon Paper for Electrocatalytic Nitrite Oxidation

Deposition of redox-active metal–organic frameworks (MOFs) as thin films on conductive substrates is of great importance to improve their electrochemical performance and durability. In this work, a series of metalloporphyrinic MOF crystals was successfully deposited as thin films on carbon fiber paper (CFP) substrates, which is an alternative to rigid glass substrates. The specific dimensions of the obtained films could be adjusted easily by simple cutting. Metalloporphyrinic MOFs on CFP with different active metal species have been employed for electrochemical conversion of the carcinogenic nitrite into the less toxic nitrate. The MOFs on CFP exhibit remarkable improvement in terms of the electrocatalytic performance and reusability compared with the electrodes prepared from MOF powder. The contribution from metal species of the porphyrin units and reaction mechanisms was elucidated based on the findings from X-ray photoelectron spectroscopy (XPS) and in situ X-ray absorption near edge structure (XANES) measured during the electrochemical reaction. By integrating the redox-active property of metalloporphyrinic MOFs and high conductivity of CFP, MOF thin films on CFP provided a significant improvement of electrocatalytic performance to detoxify the carcinogenic nitrite with good stability.     

In Situ Modification of Metal–Organic Frameworks in Mixed‐Matrix Membranes

Processable films of metal–organic frameworks (MOFs) have been long sought to advance the application of MOFs in various technologies from separations to catalysis. Herein, MOF–polymer mixed‐matrix membranes (MMMs) are described, formed on several substrates using a wide variety of MOF materials. These MMMs can be delaminated from their substrates to create free‐standing MMMs that are mechanically stable and pliable. The MOFs in these MMMs remain highly crystalline, porous, and accessible for further chemical modification through postsynthetic modification (PSM) and postsynthetic exchange (PSE) processes. Overall, the findings here demonstrate a versatile approach to preparing stable functional MMMs that should contribute significantly to the advancement of these materials.     

Electroactive Organic Building Blocks for the Chemical Design of Functional Porous Frameworks (MOFs and COFs) in Electronics

Electroactive organic molecules have received a lot of attention in the field of electronics because of their fascinating electronic properties, easy functionalization and potential low cost towards their implementation in electronic devices. In recent years, electroactive organic molecules have also emerged as promising building blocks for the design and construction of crystalline porous frameworks such as metal–organic frameworks (MOFs) and covalent-organic frameworks (COFs) for applications in electronics. Such porous materials present certain additional advantages such as, for example, an immense structural and functional versatility, combination of porosity with multiple electronic properties and the possibility of tuning their physical properties by post-synthetic modifications. In this Review, we summarize the main electroactive organic building blocks used in the past few years for the design and construction of functional porous materials (MOFs and COFs) for electronics with special emphasis on their electronic structure and function relationships. The different building blocks have been classified based on the electronic nature and main function of the resulting porous frameworks. The design and synthesis of novel electroactive organic molecules is encouraged towards the construction of functional porous frameworks exhibiting new functions and applications in electronics.     

Metal–Organic Frameworks as Catalysts for Oxidation Reactions

This Concept is aimed at describing the current state of the art in metal–organic frameworks (MOFs) as heterogeneous catalysts for liquid‐phase oxidations, focusing on three important substrates, namely, alkenes, alkanes and alcohols. Emphases are on the nature of active sites that have been incorporated within MOFs and on future targets to be set in this area. Thus, selective alkene epoxidation with peroxides or oxygen catalyzed by constitutional metal nodes of MOFs as active sites are still to be developed. Moreover, no noble metal‐free MOF has been reported to date that can act as a general catalyst for the aerobic oxidation of primary and secondary aliphatic alcohols. In contrast, in the case of alkanes, a target should be to tune the polarity of MOF internal pores to control the outcome of the autooxidation process, resulting in the selective formation of alcohol/ketone mixtures at high conversion.     

A Guest‐Dependent Approach to Retain Permanent Pores in Flexible Metal–Organic Frameworks by Cation Exchange

Two anionic metal–organic frameworks were successfully prepared based on pre‐designed flexible multicarboxylate ligands and indium cations. Owing to the flexibility of the bridging organic linkers, which could not themselves sustain the frameworks, both of the frameworks showed thermal instability and shrinkage after removal of guest solvent molecules. Inspired by bamboo, we used a guest‐dependent approach to tune the permanent porosity of the MOFs. In this approach, several tetraalkyammonium cations of different sizes were introduced into the channels by cation exchange to act as partitions and to support the main frameworks. This approach significantly enhanced the stability of the framework and its permanent porosity. Moreover, the gas‐adsorption properties (such as gate sorption, hysteresis, and selectivity) of the MOFs were also modulated by the judicious choice of guest cations.     

Synthetic Strategies for Constructing Two‐Dimensional Metal‐Organic Layers (MOLs): A Tutorial Review

Two‐dimensional (2D) metal‐organic layers (MOLs) are the 2D version of metal‐organic frameworks (MOFs) with nanometer thickness in one dimension. MOLs are also known as 2D‐MOFs, 2D coordination polymers, ultrathin MOF nanosheets (UMOFNs) or coordination nanosheets in literature. This new category of 2D materials has attracted a lot of interests because of the opportunity in combining molecular chemistry, surface/interface chemistry and material chemistry of low dimensional materials in these systems. Several synthetic strategies have been developed for the construction of 2D MOLs, but the general synthesis of MOLs still presents a challenge. This tutorial level review summarizes the recent progress in the fabrication of novel 2D MOLs and aims to highlight challenges in this field.     

以MOFs为前驱体的多孔金属氧化物催化剂研究进展

多孔金属氧化物具有高比表面积、大孔径、特殊的形貌和结构特性,广泛应用于催化、锂离子电池、太阳能电池、气敏传感器等领域。金属有机骨架材料(MOFs)是一类具有周期性网络结构的新型多孔晶体材料,在气体存储、气体分离、催化等领域具有重要的应用价值。近年来,以MOFs为前驱体制备多孔碳和多孔金属氧化物成为MOFs应用领域一个新的研究热点。本文主要综述了以MOFs为前驱体制备的多孔金属氧化物和多孔金属氧化物/碳复合物在CO氧化、催化产氢、异丁烷脱氢、环已烯氧化、醇直接氧化为酯、醛氧化酰胺化反应、光催化降解有机物和氧还原反应等方面的应用。     

Parallel Lipid Peroxide Accumulation Strategy Based on Bimetal–Organic Frameworks for Enhanced Ferrotherapy

Ferroptosis, a nonapoptotic cell-death pathway, is commonly regulated by ether lipid peroxide generation or glutathione consumption. In this work, a parallel lipid peroxide accumulation strategy was designed based on catalytic metal–organic frameworks (MOFs) for enhanced ferrotherapy. The bimetallic MOF was synthesized with iron porphyrin as a linker and cupric ion as a metal node, and erastin, a ferroptosis inducer, was sandwiched between the MOF layers with 4,4′-dipyridyl disulfide as spacers. In a tumor microenvironment, erastin was released from the layered MOFs through glutathione-responsive cleavage. The exfoliated MOFs served as a dual Fenton reaction inducer to generate numerous hydroxyl radicals for the accumulation of lipid peroxide, while erastin-aggravated glutathione depletion down-regulated glutathione peroxidase 4; this then inhibited the consumption of lipid peroxide. Therefore, a parallel lipid peroxide accumulation strategy was established for enhanced ferrotherapy that effectively inhibited tumor growth in live mice, opening up new opportunities to treat apoptosis-insensitive tumors.     

金属有机骨架及其复合材料在固相微萃取中的制备及应用

金属有机骨架材料是近几年涌现出的一类新型多功能多孔固体材料,由金属离子和有机配体自组装形成.基于其比表面积高、孔隙率大、热稳定性好和结构与功能多样化等优点,此类材料可作为潜在的吸附剂来对水体等环境污染物进行预处理分析.此外,金属有机骨架材料和不同功能材料如碳基材料、分子印迹聚合物材料以及磁性纳米粒子等组装形成的金属有机骨架复合材料,其整体性能较优于母体金属有机骨架材料.因此,金属有机骨架复合材料在样品预处理方面的应用也引起了研究者的极大兴趣和广泛关注.结合自己的研究工作,对近5年的金属有机骨架材料以及金属有机骨架复合材料,主要在固相微萃取样品预处理方面的应用进行了综述,并对其发展前景进行了展望.     

A Hierarchically Porous ZIF@LDH Core-Shell Structure for High-Performance Supercapacitors

Designing nanocomposites with good electrochemical properties is one of the challenges in constructing supercapacitors. Adjustable metal-organic frameworks (MOFs) have potential research value in improving charge storage and transfer due to their multi-porosity. Moreover, MOFs can serve as a precursor to various derivatives. Herein, a series of core-shell structures with macro-microporous ZIF-67 (M-ZIF-67) as the core and layered double hydroxide (LDH) as the shell were synthesized based on polystyrene spheres (PSs) template via a simple ion etching method. As a result, the sample of M-ZIF-67@LDH4 shows a specific capacitance of 597.6 F g⁻¹ at 0.5 A g⁻¹ and a high rate retention of 92% at 3 A g⁻¹.     

MOFs – Metallorganische Gerüststrukturen. Funktionale poröse Materialien

MOFs (metal‐organic frameworks) have developed into an important class of materials. This is due to their potential application in the fields of catalysis, gas storage, nanoreactors, or drug release. MOFs are comprised of isolated metal ions or metal‐oxygen clusters, chains or layers, which are connected via organic linkers to form three‐dimensional frameworks of outstanding porosity. Owing to their modular assembly, the pores of MOFs can be tailored using functionalized linkers, following the principle of reticular chemistry.     

A Mixed Molecular Building Block Strategy for the Design of Nested Polyhedron Metal–Organic Frameworks

A mixed molecular building block (MBB) strategy for the synthesis of double‐walled cage‐based porous metal–organic frameworks (MOFs) is presented. By means of this method, two isostructural porous MOFs built from unprecedented double‐walled metal–organic octahedron were obtained by introducing two size‐matching C₃‐symmetric molecular building blocks with different rigidities. With their unique framework structures, these MOFs provide, to the best of our knowledge, the first examples of double‐walled octahedron‐based MOFs.     

Electronic,Structural and Functional Versatility in Tetrathiafulvalene-Lanthanide Metal–Organic Frameworks

Tetrathiafulvalene-lanthanide (TTF-Ln) metal–organic frameworks (MOFs) are an interesting class of multifunctional materials in which porosity can be combined with electronic properties such as electrical conductivity, redox activity, luminescence and magnetism. Herein a new family of isostructural TTF-Ln MOFs is reported, denoted as MUV-5(Ln) (Ln=Gd, Tb, Dy, Ho, Er), exhibiting semiconducting properties as a consequence of the short intermolecular S⋅⋅⋅S contacts established along the chain direction between partially oxidised TTF moieties. In addition, this family shows photoluminescence properties and single-molecule magnetic behaviour, finding near-infrared (NIR) photoluminescence in the Yb/Er derivative and slow relaxation of the magnetisation in the Dy and Er derivatives. As such properties are dependent on the electronic structure of the lanthanide ion, the immense structural, electronic and functional versatility of this class of materials is emphasised.     

Terpyridine-Based 3D Metal–Organic-Frameworks: A Structure–Property Correlation

Design, synthesis, and applications of metal–organic frameworks (MOFs) are among the most salient fields of research in modern inorganic and materials chemistry. As the structure and physical properties of MOFs are mostly dependent on the organic linkers or ligands, the choice of ligand system is of utmost importance in the design of MOFs. One such crucial organic linker/ligand is terpyridine (tpy), which can adopt various coordination modes to generate an enormous number of metal–organic frameworks. These frameworks generally carry physicochemical characteristics induced by the π-electron-rich (basically N-electron-rich moiety) terpyridines. In this minireview, the construction of 3D MOFs associated with symmetrical terpyridines is discussed. These ligands can be easily derivatized at the lateral phenyl (4′-phenyl) position and incorporate additional organic functionalities. These functionalities lead to some different binding modes and form higher dimensional (3D) frameworks. Therefore, these 3D MOFs can carry multiple features along with the characteristics of terpyridines. Some properties of these MOFs, like photophysical, chemical selectivity, photocatalytic degradation, proton conductivity, and magnetism, etc. have also been discussed and correlated with their frameworks.