Ternary Alloys Encapsulated within Different MOFs via a Self‐Sacrificing Template Process: A Potential Platform for the Investigation of Size‐Selective Catalytic Performances

Functional nanoparticles encapsulated within metal–organic frameworks (MOFs) as an emerging class of composite materials attract increasing attention owing to their enhanced or even novel properties caused by the synergistic effect between the two functional materials. However, there is still no ideal composite structure as platform to systematically analyze and evaluate the relation between the enhanced catalytic performance of composites and the structure of MOF shells. In this work, taking RhCoNi ternary alloy nanoflowers, for example, first the RhCoNi@MOF composite catalysts sheathed with different structured MOFs via a facile self‐sacrificing template process are successfully fabricated. The structure type of MOF shells is easily adjustable by using different organic molecules as etchant and coordination reagent (e.g., 2,5‐dihydroxyterephthalic acid or 2‐methylimidazole), which can dissolve out the Co or Ni element in the alloy template in a targeted manner, thereby producing ZIF‐67(Co) or MOF‐74(Ni) shells accordingly. With the difference between the two MOF shells in the aperture sizes, the as‐prepared two RhCoNi@MOF composites preform distinct size selectivity during the alkene hydrogenation. This work would help us to get more comprehensive understanding of the intrinsic role of MOFs behind the enhanced catalytic performance of nanoparticle@MOF composites.     

Multifunctional Metal–Organic Frameworks for Photocatalysis

Metal–organic frameworks (MOFs) have attracted significant research attention in diverse areas due to their unique physical and chemical characteristics that allow their innovative application in various research fields. Recently, the application of MOFs in heterogeneous photocatalysis for water splitting, CO₂ reduction, and organic transformation have emerged, aiming at providing alternative solutions to address the world‐wide energy and environmental problems by taking advantage of the unique porous structure together with ample physicochemical properties of the metal centers and organic ligands in MOFs. In this review, the latest progress in MOF‐involved solar‐to‐chemical energy conversion reactions are summarized according to their different roles in the photoredox chemical systems, e.g., photocatalysts, co‐catalysts, and hosts. The achieved progress and existing problems are evaluated and proposed, and the opportunities and challenges of MOFs and their related materials for their advanced development in photocatalysis are discussed and anticipated.     

Ultrasmall Metal Nanoparticles Confined within Crystalline Nanoporous Materials: A Fascinating Class of Nanocatalysts

Crystalline nanoporous materials with uniform porous structures, such as zeolites and metal–organic frameworks (MOFs), have proven to be ideal supports to encapsulate ultrasmall metal nanoparticles (MNPs) inside their void nanospaces to generate high‐efficiency nanocatalysts. The nanopore‐encaged metal catalysts exhibit superior catalytic performance as well as high stability and catalytic shape selectivity endowed by the nanoporous matrix. In addition, the synergistic effect of confined MNPs and nanoporous frameworks with active sites can further promote the catalytic activities of the composite catalysts. Herein, recent progress in nanopore‐encaged metal nanocatalysts is reviewed, with a special focus on advances in synthetic strategies for ultrasmall MNPs (<5 nm), clusters, and even single atoms confined within zeolites and MOFs for various heterogeneous catalytic reactions. In addition, some advanced characterization methods to elucidate the atomic‐scale structures of the nanocatalysts are presented, and the current limitations of and future opportunities for these fantastic nanocatalysts are also highlighted and discussed. The aim is to provide some guidance for the rational synthesis of nanopore‐encaged metal catalysts and to inspire their further applications to meet the emerging demands in catalytic fields.     

Nanoarchitectured Design of Porous Materials and Nanocomposites from Metal‐Organic Frameworks

The emergence of metal‐organic frameworks (MOFs) as a new class of crystalline porous materials is attracting considerable attention in many fields such as catalysis, energy storage and conversion, sensors, and environmental remediation due to their controllable composition, structure and pore size. MOFs are versatile precursors for the preparation of various forms of nanomaterials as well as new multifunctional nanocomposites/hybrids, which exhibit superior functional properties compared to the individual components assembling the composites. This review provides an overview of recent developments achieved in the fabrication of porous MOF‐derived nanostructures including carbons, metal oxides, metal chalcogenides (metal sulfides and selenides), metal carbides, metal phosphides and their composites. Finally, the challenges and future trends and prospects associated with the development of MOF‐derived nanomaterials are also examined.     

Metal–Organic Frameworks and Their Derived Materials: Emerging Catalysts for a Sulfate Radicals‐Based Advanced Oxidation Process in Water Purification

With the ever‐growing environmental issues, sulfate radical (SO₄^??)‐based advanced oxidation processes (SR‐AOPs) have been attracting widespread attention due to their high selectivity and oxidative potential in water purification. Among various methods generating SO₄^??, employing heterogeneous catalysts for activation of peroxymonosulfate or persulfate has been demonstrated as an effective strategy. Therefore, the future advances of SR‐AOPs depend on the development of adequate catalysts with high activity and stability. Metal–organic frameworks (MOFs) with large surface area, ultrahigh porosity, and diversity of material design have been extensively used in heterogeneous catalysts, and more recently, enormous effort has been made to utilize MOFs‐based materials for SR‐AOPs applications. In this work, the state‐of‐the‐art research on pristine MOFs, MOFs composites, and their derivatives, such as oxides, metal/carbon hybrids, and carbon materials for SR‐AOPs, is summarized. The mechanisms, including radical and nonradical pathways, are also detailed in the discussion. This work will hopefully promote the future development of MOFs‐based materials toward SR‐AOPs applications.     

Metal‐Organic Frameworks for CO2 Chemical Transformations

Carbon dioxide (CO₂), as the primary greenhouse gas in the atmosphere, triggers a series of environmental and energy related problems in the world. Therefore, there is an urgent need to develop multiple methods to capture and convert CO₂ into useful chemical products, which can significantly improve the environment and promote sustainable development. Over the past several decades, metal‐organic frameworks (MOFs) have shown outstanding heterogeneous catalytic activity due in part to their high internal surface area and chemical functionalities. These properties and the ability to synthesize MOF platforms allow experiments to test structure‐function relationships for transforming CO₂ into useful chemicals. Herein, recent developments are highlighted for MOFs participating as catalysts for the chemical fixation and photochemical reduction of CO₂. Finally, opportunities and challenges facing MOF catalysts are discussed in this ongoing research area.     

Self‐Template‐Directed Metal–Organic Frameworks Network and the Derived Honeycomb‐Like Carbon Flakes via Confinement Pyrolysis

Metal–organic frameworks (MOFs) have become a research hotspot since they have been explored as convenient precursors for preparing various multifunctional nanomaterials. However, the preparation of MOF networks with controllable flake morphology in large scale is not realized yet. Herein, a self‐template strategy is developed to prepare MOF networks. In this work, layered double‐metal hydroxide (LDH) and other layered metal hydroxides are used not only as a scaffold but also as a self‐sacrificed metal source. After capturing the abundant metal cations identically from the LDH by the organic linkers, MOF networks are in situ formed. It is interesting that the MOF network‐derived carbon materials retain the flake morphology and exhibit a unique honeycomb‐like macroporous structure due to the confined shrinkage of the polyhedral facets. The overall properties of the carbon networks are adjustable according to the tailored metal compositions in LDH and the derived MOFs, which are desirable for target‐oriented applications as exemplified by the electrochemical application in supercapacitors.     

Engineering Homochiral Metal‐Organic Frameworks for Heterogeneous Asymmetric Catalysis and Enantioselective Separation

Owing to the potential applications in technological areas such as gas storage, catalysis, separation, sensing and nonlinear optics, tremendous efforts have been devoted to the development of porous metal‐organic frameworks (MOFs) over the past ten years. Homochiral porous MOFs are particularly attractive candidates as heterogeneous asymmetric catalysts and enantioselective adsorbents and separators for production of optically active organic compounds due to the lack of homochiral inorganic porous materials such as zeolites. In this review, we summarize the recent research progress in homochiral MOF materials, including their synthetic strategy, distinctive structural features and latest advances in asymmetric heterogeneous catalysis and enantioselective separation.     

磁性金属有机复合材料的合成与应用

金属有机框架材料(MOFs)是一种将金属离子中心与有机配体通过配位键结合起来的一类具有网格结构的材料。由于金属离子以及有机配体的多样性,MOFs的结构也具有多样性。磁性金属有机复合材料是一种新型的复合材料,既结合了MOFs的网状结构及结构多变性的优点,又结合了磁性材料易于分离且可重复利用的特性,使得这种材料在药物载体、多相催化、选择吸附等多种方面都有着较为广泛的应用。以经典的几类MOFs为分类依据,研究了它们与磁性材料结合形成新型复合材料的方法,同时概括了这些新型复合材料在不同领域的应用,最后提出了该材料目前所存在的问题,并对今后的研究方向进行了展望。     

Encapsulation of Single Plasmonic Nanoparticles within ZIF‐8 and SERS Analysis of the MOF Flexibility

Hybrid nanostructures composed of metal nanoparticles and metal‐organic frameworks (MOFs) have recently received increasing attention toward various applications due to the combination of optical and catalytic properties of nanometals with the large internal surface area, tunable crystal porosity and unique chemical properties of MOFs. Encapsulation of metal nanoparticles of well‐defined shapes into porous MOFs in a core–shell type configuration can thus lead to enhanced stability and selectivity in applications such as sensing or catalysis. In this study, the encapsulation of single noble metal nanoparticles with arbitrary shapes within zeolitic imidazolate‐based metal organic frameworks (ZIF‐8) is demonstrated. The synthetic strategy is based on the enhanced interaction between ZIF‐8 nanocrystals and metal nanoparticle surfaces covered by quaternary ammonium surfactants. High resolution electron microscopy and tomography confirm a complete core–shell morphology. Such a well‐defined morphology allowed us to study the transport of guest molecules through the ZIF‐8 porous shell by means of surface‐enhanced Raman scattering by the metal cores. The results demonstrate that even molecules larger than the ZIF‐8 aperture and pore size may be able to diffuse through the framework and reach the metal core.     

Rational Design of Catalytic Centers in Crystalline Frameworks

Crystalline frameworks including primarily metal organic frameworks (MOF) and covalent organic frameworks (COF) have received much attention in the field of heterogeneous catalysts recently. Beyond providing large surface area and spatial confinement, these crystalline frameworks can be designed to either directly act as or influence the catalytic sites at molecular level. This approach offers a unique advantage to gain deeper insights of structure–activity correlations in solid materials, leading to new guiding principles for rational design of advanced solid catalysts for potential important applications related to energy and fine chemical synthesis. In this review, recent key progress achieved in designing MOF‐ and COF‐based molecular solid catalysts and the mechanistic understanding of the catalytic centers and associated reaction pathways are summarized. The state‐of‐the‐art rational design of MOF‐ and COF‐based solid catalysts in this review is grouped into seven different areas: (i) metalated linkers, (ii) metalated moieties anchored on linkers, (iii) organic moieties anchored on linkers, (iv) encapsulated single sites in pores, and (v) metal‐mode‐based active sites in MOFs. Along with this, some attention is paid to theoretical studies about the reaction mechanisms. Finally, technical challenges and possible solutions in applying these catalysts for practical applications are also presented.     

State‐of‐the‐Art Advances and Challenges of Iron‐Based Metal Organic Frameworks from Attractive Features,Synthesis to Multifunctional Applications

Metal organic frameworks (MOFs), as an original kind of organic–inorganic porous material, are constructed with metal centers and organic linkers via a coordination complexation reaction. Among uncountable MOF materials, iron‐containing metal organic frameworks (Fe‐MOFs) have excellent potential in practical applications owing to their many fascinating properties, such as diverse structure types, low toxicity, preferable stability, and tailored functionality. Here, recent research progresses of Fe‐MOFs in attractive features, synthesis, and multifunctional applications are described. Fe‐MOFs with porosity and tailored functionality are discussed according to the design of building blocks. Four types of synthetic methods including solvothermal, hydrothermal, microwave, and dry gel conversion synthesis are illustrated. Finally, the applications of Fe‐MOFs in Li‐ion batteries, sensors, gas storage, separation in gas and liquid phases, and catalysis are elucidated, focusing on the mechanism. The aim is to provide prospects for extending Fe‐MOFs in more practical applications.     

Asymmetric Catalysis within the Chiral Confined Space of Metal–Organic Architectures

The effective synthesis of chiral compounds in a highly enantioselective manner is obviously attractive. Inspired by the enzymatic reactions that occur in pocket‐like cavities with high efficiency and specificity, chemists are seeking to construct catalysts that mimic this key feature of enzymes. Recent progress in supramolecular coordination chemistry has shown that metal–organic cages (MOCs) and metal–organic frameworks (MOFs) with chiral confined cavities/pores may offer a novel platform for achieving asymmetric catalysis with high enantioselectivity. The inherent chiral confined microenvironment is considered to be analogous to the binding pocket of enzymes, and this pocket promotes enantioselective transformations. This work focuses on the recent advances in MOCs and MOFs with chiral confined spaces for asymmetric catalysis, and each section is separated into two parts based on how the chirality is achieved in these metal–organic architectures. A special emphasis is placed on discussing the relationship between the enantioselectivity and the confined spaces of the chiral functional MOCs and MOFs rather than catalytic chemistry. Finally, current challenges and perspectives are discussed. This work is anticipated to offer researchers insights into the design of sophisticated chiral confined space‐based metal–organic architectures for asymmetric catalysis with high enantioselectivity.     

Iron‐Based Metal–Organic Frameworks as Catalysts for Visible Light‐Driven Water Oxidation

The development of earth‐abundant, active, and stable catalysts is important for solar energy conversion. Metal‐organic frameworks (MOFs) have been viewed as a promising class of porous materials, which may have innovative application in photocatalysis. In this paper, three types of Fe‐based MOFs and their aminofunctionalized derivatives have been fabricated and systematically studied as water oxidation catalysts (WOCs) for oxygen evolution under visible light irradiation. MIL‐101(Fe) possesses a higher current density and earlier onset potential and exhibits excellent visible light‐driven oxygen evolution activity than the other Fe‐based catalysts. It speeds up the oxygen evolution reaction rate with the higher initial turnover frequencies value of 0.10 s^?1. Our study demonstrates that Fe‐based MOFs as efficient WOCs are promising candidates for photocatalytic water oxidation process.     

Metal–Organic Frameworks Based Nano/Micro/Millimeter‐Sized Self‐Propelled Autonomous Machines

Synthetic nano/micro/millimeter‐sized machines that harvest energy from the surrounding environment and then convert it to motion have had a significant impact on many research areas such as biology (sensing, imaging, and therapy) and environmental applications. Autonomous motion is a key element of these devices. A high surface area is preferable as it leads to increased propellant or cargo‐loading capability. Integrating highly ordered and porous metal–organic frameworks (MOFs) with self‐propelled machines is demonstrated to have a significant impact on the field of nano/micro/millimeter‐sized devices for a wide range of applications. MOFs have shown great potential in many research fields due to their tailorable pore size. These fields include energy storage and conversion; catalysis, biomedical application (e.g., drug delivery, imaging, and cancer therapy), and environmental remediation. The marriage of motors and MOFs may provide opportunities for many new applications for synthetic nano/micro/millimeter‐sized machines. Herein, MOF‐based micro‐ and nanomachines are reviewed with a focus on the specific properties of MOFs.     

Ultrathin 2D Zirconium Metal–Organic Framework Nanosheets: Preparation and Application in Photocatalysis

Synthesizing ultrathin 2D metal–organic framework nanosheets in high yields has received increasing research interest but remains a great challenge. In this work, ultrathin zirconium‐porphyrinic metal–organic framework (MOF) nanosheets with thickness down to ≈1.5 nm are synthesized through a pseudoassembly–disassembly strategy. Owing to the their unique properties originating from their ultrathin thickness and highly exposed active sites, the as‐prepared ultrathin nanosheets exhibit far superior photocatalysis performance compared to the corresponding bulk MOF. This work highlights new opportunities in designing ultrathin MOF nanosheets and paves the way to expand the potential applications of MOFs.     

Heterogeneous Catalysis in Zeolites,Mesoporous Silica,and Metal–Organic Frameworks

Crystalline porous materials are important in the development of catalytic systems with high scientific and industrial impact. Zeolites, ordered mesoporous silica, and metal–organic frameworks (MOFs) are three types of porous materials that can be used as heterogeneous catalysts. This review focuses on a comparison of the catalytic activities of zeolites, mesoporous silica, and MOFs. In the first part of the review, the distinctive properties of these porous materials relevant to catalysis are discussed, and the corresponding catalytic reactions are highlighted. In the second part, the catalytic behaviors of zeolites, mesoporous silica, and MOFs in four types of general organic reactions (acid, base, oxidation, and hydrogenation) are compared. The advantages and disadvantages of each porous material for catalytic reactions are summarized. Conclusions and prospects for future development of these porous materials in this field are provided in the last section. This review aims to highlight recent research advancements in zeolites, ordered mesoporous silica, and MOFs for heterogeneous catalysis, and inspire further studies in this rapidly developing field.     

Synthesis of Bimetallic Conductive 2D Metal–Organic Framework (CoxNiy‐CAT) and Its Mass Production: Enhanced Electrochemical Oxygen Reduction Activity

The development of new electrocatalysts for electrochemical oxygen reduction to replace expensive and rare platinum‐based catalysts is an important issue in energy storage and conversion research. In this context, conductive and porous metal–organic frameworks (MOFs) are considered promising materials for the oxygen reduction reaction (ORR) due to not only their high surface area and well‐developed pores but also versatile structural features and chemical compositions. Herein, the preparation of bimetallic conductive 2D MOFs (Co_xNi_y‐CATs) are reported for use as catalysts in the ORR. The ratio of the two metal ions (Co²⁺ and Ni²⁺) in the bimetallic Co_xNi_y‐CATs is rationally controlled to determine the optimal composition of Co_xNi_y‐CAT for efficient performance in the ORR. Indeed, bimetallic MOFs display enhanced ORR activity compared to their monometallic counterparts (Co‐CAT or Ni‐CAT). During the ORR, bimetallic Co_xNi_y‐CATs retain an advantageous characteristic of Co‐CAT in relation to its high diffusion‐limiting current density, as well as a key advantage of Ni‐CAT in relation to its high onset potential. Moreover, the ORR‐active bimetallic Co_xNi_y‐CAT with excellent ORR activity is prepared at a large scale via a convenient method using a ball‐mill reactor.     

Confined Heteropoly Blues in Defected Zr‐MOF (Bottle Around Ship) for High‐Efficiency Oxidative Desulfurization

The Keggin‐type polyoxometalates (POMs) are effective catalysts for oxidative desulfurization (ODS) and confining these POMs in metal–organic frameworks (MOFs) is a promising strategy to improve their performances. Herein, postsynthetic modification of POMs confined in MOFs by adding thiourea creates more unsaturated metal sites as defects, promoting ODS catalytic activity. Additional modification by confining 1‐butyl‐3‐methyl imidazolium POMs in MOFs is performed to obtain higher ODS activity, owing to the affinity between electron‐rich thiophene‐based compounds and electrophilic imidazolium compounds. The ODS catalytic activities of four Zr‐MOF‐based composites (bottle around ship) including phosphomolybdate acid (PMA)/UiO‐66, [Bmim]₃PMo₁₂O₄₀/UiO‐66, PMA/Thiourea/UiO‐66, and [Bmim]₃PMo₁₂O₄₀/Thiourea/UiO‐66 are therefore investigated in detail. In order to explore the catalytic mechanism of these MOF composites, their microstructures and electronic structures are probed by various techniques such as X‐ray diffraction, thermogravimetric analysis, Fourier transform infrared, Raman, scanning electron microscope, transmission electron microscope, BET, X‐ray photoelectron spectroscopy, EPR, UV–vis, NMR spectra, and H₂‐temperature‐programmed reduction. The results reveal that phosphomolybdate blues and imidazolium phosphomolybdate blues with different Mo⁵⁺/Mo⁶⁺ ratios with the Keggin structure are confined in defected UiO‐66 for all four composites. This approach can be applied to design and synthesize other POMs/MOFs composites as efficient catalysts.     

2D Metal–Organic Frameworks (MOFs) for High‐Performance BatCap Hybrid Devices

Two identical layered metal–organic frameworks (MOFs) (CoFRS and NiFRS) are constructed by using flexible 1,10‐bis(1,2,4‐triazol‐1‐yl)decane as pillars and 1,4‐benzenedicarboxylic acid as rigid linkers. The single‐crystal structure analysis indicates that the as‐synthesized MOFs possess fluctuant 2D networks with large interlayer lattices. Serving as active electrode elements in supercapacitors, both MOFs deliver excellent rate capabilities, high capacities, and longstanding endurances. Moreover, the new intermediates in two electrodes before and after long‐lifespan cycling are also examined, which cannot be identified as metal hydroxides in the peer reports. After assembled into battery‐supercapacitor (BatCap) hybrid devices, the NiFRS//activated carbon (AC) device displays better electrochemical results in terms of gravimetric capacitance and cycling performance than CoFRS//AC devices, and a higher energy‐density value of 28.7 Wh kg^?1 compared to other peer references with MOFs‐based electrodes. Furthermore, the possible factors to support the distinct performances are discussed and analyzed.