A Review on Metal-Organic Framework-Derived Porous Carbon-Based Novel Microwave Absorption Materials

The development of microwave absorption materials(MAMs) is a considerable important topic because our living space is crowed with electromagnetic wave which threatens human’s health.And MAMs are also used in radar stealth for protecting the weapons from being detected.Many nanomaterials were studied as MAMs,but not all of them have the satisfactory performance.Recently,metal-organic frameworks(MOFs) have attracted tremendous attention owing to their tunable chemical structures,diverse properties,large specific surface area and uniform pore distribution.MOF can transform to porous carbon(PC) which is decorated with metal species at appropriate pyrolysis temperature.However,the loss mechanism of pure MOF-derived PC is often relatively simple.In order to further improve the MA performance,the MOFs coupled with other loss materials are a widely studied method.In this review,we summarize the theories of MA,the progress of different MOF-derived PC-based MAMs,tunable chemical structures incorporated with dielectric loss or magnetic loss materials.The different MA performance and mechanisms are discussed in detail.Finally,the shortcomings,challenges and perspectives of MOF-derived PC-based MAMs are also presented.We hope this review could provide a new insight to design and fabricate MOF-derived PC-based MAMs with better fundamental understanding and practical application.

State of the Art and Prospects in Metal-Organic Framework-Derived Microwave Absorption Materials

Microwave has been widely used in many fields,including communication,medical treatment and military industry;however,the corresponding generated radiations have been novel hazardous sources of pollution threating human’s daily life.Therefore,designing high-performance microwave absorption materials(MAMs)has become an indispensable requirement.Recently,metal-organic frameworks(MOFs)have been considered as one of the most ideal precursor candidates of MAMs because of their tunable structure,high porosity and large specific surface area.Usually,MOF-derived MAMs exhibit excellent electrical conductivity,good magnetism and sufficient defects and interfaces,providing obvious merits in both impedance matching and microwave loss.In this review,the recent research progresses on MOF-derived MAMs were profoundly reviewed,including the categories of MOFs and MOF composites precursors,design principles,preparation methods and the relationship between mechanisms of microwave absorption and microstructures of MAMs.Finally,the current challenges and prospects for future opportunities of MOF-derived MAMs are also discussed.

Metal-Organic Framework Materials for Electrochemical Supercapacitors

Exploring new materials with high stability and capacity is full of challenges in sustainable energy conversion and storage systems.Metal-organic frameworks(MOFs),as a new type of porous material,show the advantages of large specific surface area,high porosity,low density,and adjustable pore size,exhibiting a broad application prospect in the field of electrocatalytic reactions,batteries,particularly in the field of supercapacitors.This comprehensive review outlines the recent progress in synthetic methods and electrochemical performances of MOF materials,as well as their applications in supercapacitors.Additionally,the superiorities of MOFs-related materials are highlighted,while major challenges or opportunities for future research on them for electrochemical supercapacitors have been discussed and displayed,along with extensive experimental experiences.

Anion-immobilized solid composite electrolytes based on metal-organic frameworks and superacid ZrO_(2) fillers for high-performance all solid-state lithium metal batteries

Anion-immobilized solid composite electrolytes(SCEs)are important to restrain the propagation of lithium dendrites for all solid-state lithium metal batteries(ASSLMBs).Herein,a novel SCEs based on metal-organic frameworks(MOFs,UiO-66-NH_(2))and superacid ZrO_(2)(S-ZrO_(2))fillers are proposed,and the samples were characterized by X-ray diffraction(XRD),scanning electron microscope(SEM),energy dispersive X-ray spectroscopy(EDS),thermo-gravimetric analyzer(TGA)and some other electrochemical measurements.The-NH_(2) groups of UiO-66-NH_(2) combines with F atoms of poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)chains by hydrogen bonds,leading to a high electrochemical stability window of 5 V.Owing to the incorporation of UiO-66-NH_(2) and S-ZrO_(2) in PVDF-HFP polymer,the open metal sites of MOFs and acid surfaces of S-ZrO_(2) can immobilize anions by strong Lewis acid-base interaction,which enhances the effect of immobilization anions,achieving a high Li-ion transference number(t_(+))of 0.72,and acquiring a high ionic conductivity of 1.05×10^(-4) S·cm^(-1) at 60℃.The symmetrical Li/Li cells with the anion-immobilized SCEs may steadily operate for over 600 h at 0.05 mA·cm^(-2) without the shortcircuit occurring.Besides,the solid composite Li/LiFePO_(4)(LFP)cell with the anion-immobilized SCEs shows a superior discharge specific capacity of 158 mAh·g^(-1) at 0.2 C.The results illustrate that the anion-immobilized SCEs are one of the most promising choices to optimize the performances of ASSLMBs.

Metal-Organic Framework-Based Sulfur-Loaded Materials

Lithium-sulfur batteries(LSBs)are considered promising new energy storage systems given their outstanding theoretical energy densities.Nevertheless,issues such as low electrical conductivity and severe volume expansion,along with the formation of polysulfides during cycling,restrict their practical applications.To overcome these issues,it is necessary to find suitable and effective sulfur host materials.Metal-organic frameworks(MOFs),which are porous crystalline materials in the bourgeoning developmental stages,have demonstrated enormous potential in LSBs owing to their high porosity and tunable porous structure.Herein,we provide a comprehensive overview of MOF-based sulfur-loaded materials and discuss the charge/discharge mechanisms,strategies of enhancing battery performance,sulfur loading methods,and applications in LSBs.An outlook on future directions,prospects,and possible obstacles for the development of these materials is also provided.

Metal-organic framework composites for energy conversion and storage

Metal-organic frameworks(MOFs)with orderly porous structure,large surface area,high electrochemical response and chemical tunability have been widely studied for energy conversion and storage.However,most reported MOFs still suffer from poor stability,insufficient conductivity,and low utilization of active sites.One strategy to circumvent these issues is to optimize MOFs via designing composites.Here,the design principle from the viewpoint of the intrinsic relationships among various components will be illuminated to acquire the synergistic effects,including two working modes:(1)MOFs with assistant components,(2)MOFs with other function components.This review introduces recent research progress of MOF-based composites with their typical applications in energy conversion(catalysis)and storage(supercapacitor and ion battery).Finally,the challenges and future prospects of MOF-based composites will be discussed in terms of maximizing composite properties.

Laminar Composite Solid Electrolyte with Poly(Ethylene Oxide)-Threaded Metal-Organic Framework Nanosheets for High-Performance All-Solid-State Lithium Battery

Developing laminar composite solid electrolyte with ultrathin thickness and continuous conduction channels in vertical direction holds great promise for all-solid-state lithium batteries.Herein,a thin,laminar solid electrolyte is synthesized by filtrating–NH 2 functionalized metal-organic framework nanosheets and then being threaded with poly(ethylene oxide)chains induced by the hydrogen-bonding interaction from–NH_(2) groups.It is demonstrated that the threaded poly(ethylene oxide)chains lock the adjacent metal-organic framework nanosheets,giving highly enhanced structural stability(Young’s modulus,1.3 GPa)to 7.5-μm-thick laminar composite solid electrolyte.Importantly,these poly(ethylene oxide)chains with stretching structure serve as continuous conduction pathways along the chains in pores.It makes the non-conduction laminar metal-organic framework electrolyte highly conductive:3.97×10^(−5) S cm^(−1) at 25℃,which is even over 25 times higher than that of pure poly(ethylene oxide)electrolyte.The assembled lithium cell,thus,acquires superior cycling stability,initial discharge capacity(148 mAh g^(−1) at 0.5 C and 60℃),and retention(94% after 150 cycles).Besides,the pore size of nanosheet is tailored(24.5–40.9˚A)to evaluate the mechanisms of chain conformation and ion transport in confined space.It shows that the confined pore only with proper size could facilitate the stretching of poly(ethylene oxide)chains,and meanwhile inhibit their disorder degree.Specifically,the pore size of 33.8˚A shows optimized confinement effect with trans-poly(ethylene oxide)and cis-poly(ethylene oxide)conformation,which offers great significance in ion conduction.Our design of poly(ethylene oxide)-threaded architecture provides a platform and paves a way to the rational design of next-generation high-performance porous electrolytes.

Covalent organic frameworks/carbon nanotubes composite with cobalt(II)pyrimidine sites for bifunctional oxygen electrocatalysis

With characteristics and advantages of functional composite materials,they are commendably adopted in numerous fields especially in oxygen electrocatalysis,which is due to the significant synergies between various components.Herein,a novel bifunctional oxygen electrocatalyst(Co-CNT@COF-Pyr)has been synthesized through in-situ growth of covalent organic frameworks(COFs)layers on the outer surface of highly conductive carbon nanotubes(CNTs)followed by coordination with Co(Ⅱ).For electrocatalytic OER,Co-CNT@COF-Pyr reveals a low overpotential(438 mV)in alkaline electrolyte(1.0 M aqueous solution of KOH)with a current density of 10 mA cm^(-2),which is comparable to most discovered COF-based catalysts.For electrocatalytic ORR,CoCNT@COF-Pyr exhibits a low H_(2)O_(2) yield range(9.0%-10.1%)and a reaction pathway close to 4e^(-)(n=3.82-3.80)in alkaline electrolyte(0.1 M aqueous solution of KOH)within the test potential range of 0.1-0.6 V vs.RHE,which is superior to most reported COF-based catalysts.Hence,this research could not only offer an innovative insight into the construction of composites,but also facilitate the practical application of renewable fuel cells,closed water cycle,and rechargeable metal-air batteries.

Strategies for engineering metal-organic frameworks as efficient photocatalysts

Environmental pollution and energy deficiency represent major problems for the sustainability of the modern world. Photocatalysis has recently emerged as an effective and environmentally friendly technique to address some of these sustainability issues,although the key to the success of this approach is dependent on the photocatalysts themselves. Based on their attractive physic chemical properties,including their ultrahigh surface areas,homogeneous active sites and tunable functionality,metal-organic frameworks（MOFs） have become interesting platforms for the development of solar energy conversion devices. Furthermore,MOFs have recently been used in a wide variety of applications,including heterogeneous photocatalysis for pollutant degradation,organic transformations,hydrogen production and CO2 reduction. In this review,we have highlighted recent progress towards the application of MOFs in all of these areas. We have collected numerous reported examples of the use of MOFs in these areas,as well as providing some analysis of the key factors influencing the efficiency of these systems. Moreover,we have provided a detailed discussion of new strategies that have been developed for enhancing the photocatalytic activity of MOFs. Finally,we have provided an outlook for this area in terms of the future challenges and potential prospects for MOFs in photocatalysis.

Laser‑Induced and MOF‑Derived Metal Oxide/Carbon Composite for Synergistically Improved Ethanol Sensing at Room temperature

Advancements in sensor technology have significantly enhanced atmospheric monitoring.Notably,metal oxide and carbon(MO_(x)/C)hybrids have gained attention for their exceptional sensitivity and room-temperature sensing performance.However,previous methods of synthesizing MO_(x)/C composites suffer from problems,including inhomogeneity,aggregation,and challenges in micropatterning.Herein,we introduce a refined method that employs a metal–organic framework(MOF)as a precursor combined with direct laser writing.The inherent structure of MOFs ensures a uniform distribution of metal ions and organic linkers,yielding homogeneous MO_(x)/C structures.The laser processing facilitates precise micropatterning(<2μm,comparable to typical photolithography)of the MO_(x)/C crystals.The optimized MOF-derived MO_(x)/C sensor rapidly detected ethanol gas even at room temperature(105 and 18 s for response and recovery,respectively),with a broad range of sensing performance from 170 to 3,400 ppm and a high response value of up to 3,500%.Additionally,this sensor exhibited enhanced stability and thermal resilience compared to previous MOF-based counterparts.This research opens up promising avenues for practical applications in MOF-derived sensing devices.

Electrostatic Interaction-directed Construction of Hierarchical Nanostructured Carbon Composite with Dual Electrical Conductive Networks for Zinc-ion Hybrid Capacitors with Ultrastability

Metal-organic framework(MOF)-derived carbon composites have been considered as the promising materials for energy storage.However,the construction of MOF-based composites with highly controllable mode via the liquid-liquid synthesis method has a great challenge because of the simultaneous heterogeneous nucleation on substrates and the self-nucleation of individual MOF nanocrystals in the liquid phase.Herein,we report a bidirectional electrostatic generated self-assembly strategy to achieve the precisely controlled coatings of single-layer nanoscale MOFs on a range of substrates,including carbon nanotubes(CNTs),graphene oxide(GO),MXene,layered double hydroxides(LDHs),MOFs,and SiO_(2).The obtained MOF-based nanostructured carbon composite exhibits the hierarchical porosity(V_(meso)/V_(micro)∶2.4),ultrahigh N content of 12.4 at.%and"dual electrical conductive networks."The assembled aqueous zinc-ion hybrid capacitor(ZIC)with the prepared nanocarbon composite as a cathode shows a high specific capacitance of 236 F g^(-1)at 0.5 A g^(-1),great rate performance of 98 F g^(-1)at 100 A g^(-1),and especially,an ultralong cycling stability up to 230000 cycles with the capacitance retention of 90.1%.This work develops a repeatable and general method for the controlled construction of MOF coatings on various functional substrates and further fabricates carbon composites for ZICs with ultrastability.

Hierarchical Metal-Organic Frameworks with Macroporosity:Synthesis, Achievements,and Challenges

Introduction of multiple pore size regimes into metalorganic frameworks(MOFs)to form hierarchical porous structures can lead to improved performance of the material in various applications.In many cases,where interactions with bulky molecules are involved,enlarging the pore size of typically microporous MOF adsorbents or MOF catalysts is crucial for enhancing both mass transfer and molecular accessibility.In this review,we examine the range of synthetic strategies which have been reported thus far to prepare hierarchical MOFs or MOF composites with added macroporosity.These fabrication techniques can be either pre-or post-synthetic and include using hard or soft structural template agents,defect formation,routes involving supercritical CO2,and 3D printing.We also discuss potential applications and some of the challenges involved with current techniques,which must be addressed if any of these approaches are to be taken forward for industrial applications.

Two-dimensional MOF-based materials:Preparations and applications as electrodes in Li-ion batteries

Two-dimensional(2D)metal-organic frameworks(MOFs)are rapidly emerging as a unique class of mushrooming family of 2D materials offering distinctive features,such as hierarchical porosity,extensive surface area,easily available active sites,and versatile,adaptable structures.These promising characteristics have positioned them as highly appealing alternatives for a wide range of applications in energy storage technologies,including lithium batteries.Nevertheless,the poor conductivity and limited stability of 2D MOFs have limited their real applications in electrochemical energy storage.These limitations have therefore warranted ongoing research to enhance the performance of 2D MOFs.Given the significance of 2D MOF-based materials as an emerging class of advanced materials,a multitude of strategy has been devised to address these challenges such as synthesizing 2D conductive MOFs and derivatives along with 2D MOF hybridization.One promising approach involves the use of 2D MOF derivatives,including transition metal oxides,which due to their abundant unsatu rated active metal sites and shorter diffusion paths,offer superior electrochemical performance.Additionally,by combining pristine 2D MOFs with other materials,hybrid 2D MOF materials can be created.These hybrids,with their enhanced stability and conductivity,can be directly utilized as active materials in lithium batteries.In the present review,we categorize 2D MOF-based materials into three distinct groups:pristine 2D MOFs,2D MOFderived materials,and 2D MOF hybrid materials.The synthesis methods for each group,along with their specific applications as electrode materials in lithium-ion batteries,are discussed in detail.This comprehensive review provides insights into the potential of 2D MOFs while highlighting the opportunities and challenges that are present in this evolving field.

From Zeolitic Imidazolate Framework-8 to Metal-Organic Frameworks (MOFs): Representative Substance for the General Study of Pioneering MOF Applications

Metal-organic frameworks(MOFs)have been intensely studied for the past few decades as an enormous family of highly tunable porous materials with promisingly applicable functionalities in adsorption,separation,catalysis,sensing,electrochemistry,and a great number of emerging purposes.As a classic MOF,zeolitic imidazolate framework-8(ZIF-8)is conventionally one of the very few MOF members that has been commercialized with considerable production.

Amorphous nickel-cobalt bimetal-organic framework nanosheets with crystalline motifs enable efficient oxygen evolution reaction: Ligands hybridization engineering

Development of high-efficiency and low-cost electrocatalyst for oxygen evolution reaction(OER) is very important for use at alkaline water electrolysis.Metal-organic frameworks(MOF) provide a rich platform for designing multi-functional materials due to their controllable composition and ultra-high surface area.Herein,we report our findings in the development of amorphous nickel-cobalt bimetal-organic framework nanosheets with crystalline motifs via a simple "ligands hybridization engineering" strategy.These complexes' ligands contain inorganic ligands(H_2 O and NO_3) and organic ones,hexamethylenetetramine(HMT).Further,we investigated a series of mixed-metal with multi-ligands materials as OER catalysts to explore their possible advantages and features.It is found that the Ni doping is an effective approach for optimizing the electronic configuration,changing lattice ordering degree,and thus enhancing activities of HMT-based electrocatalysts.Also,the crystalline-amorphous boundaries of various HMTbased electrocatalyst can be easily controlled by simply changing amounts of Ni-precursor added.As a result,the optimized ultrathin(Co,0.3 Ni)-HMT nanosheets can reach a current density of 10 mA cm^(-2)at low overpotential of 330 mV with a small Tafel slope of 66 mV dec^(-1).Our findings show that the electronic structure changes induced by Ni doping,2 D nanosheet structure,and MOF frameworks with multiligands compositions play critical roles in the enhancement of the kinetically sluggish electrocatalytic OER.The present study emphasizes the importance of ligands and active metals via hybridization for exploring novel efficient electrocatalysts.

Recent Progress in Synthesis, Mechanism and Applications of Zinc-Based Metal-Organic Frameworks for Fluorescent Sensing

As more and more pollutants threaten human health, it is necessary and essential to develop sensitive, accurate and rapid methods and sensory materials to detect harmful substance. Metal-organic frameworks (MOFs) are inorganic-organic hybrids assembled from inorganic metal ions or clusters and suitable organic ligands. Zinc-based MOFs (Zn-MOFs) have emerged as one of the most promising sensory material of MOFs for practical applications, and attracted significant attention due to structural diversity and incomparable stability properties. However, there are few reviews on systemic summary of synthesis design, mechanism and application of Zn-MOFs. In this review, we summarize the synthesis design methods, structure types and luminescence mechanism of Zn-MOFs sensor recognition in the past ten years and their applications in metal cations, anions, organic compounds and other analytes. Finally, we present a short conclusion, and look forward to the future development direction of Zn-MOFs.

A review on anode materials for lithium/sodium-ion batteries

Since lithium-ion batteries(LIBs) have been substantially researched in recent years, they now possess exceptional energy and power densities, making them the most suited energy storage technology for use in developed and developing industries like stationary storage and electric cars, etc. Concerns about the cost and availability of lithium have prompted research into alternatives, such as sodium-ion batteries(SIBs), which use sodium instead of lithium as the charge carrier. This is especially relevant for stationary applications, where the size and weight of battery are less important. The working efficiency and capacity of these batteries are mainly dependent on the anode, cathode, and electrolyte. The anode,which is one of these components, is by far the most important part of the rechargeable battery.Because of its characteristics and its structure, the anode has a tremendous impact on the overall performance of the battery as a whole. Keeping the above in view, in this review we critically reviewed the different types of anodes and their performances studied to date in LIBs and SIBs. The review article is divided into three main sections, namely:(i) intercalation reaction-based anode materials;(ii) alloying reaction-based anode materials;and(iii) conversion reaction-based anode materials, which are further classified into a number of subsections based on the type of material used. In each main section, we have discussed the merits and challenges faced by their particular system. Afterward, a brief summary of the review has been discussed. Finally, the road ahead for better application of Li/Na-ion batteries is discussed, which seems to mainly depend on exploring the innovative materials as anode and on the inoperando characterization of the existing materials for making them more capable in terms of application in rechargeable batteries.

High-Performance Aqueous Zinc-Ion Batteries Realized by MOF Materials

Rechargeable aqueous zinc-ion batteries(ZIB s) have been gaining increasing interest for large-scale energy storage applications due to their high safety,good rate capability,and low cost.However,the further development of ZIB s is impeded by two main challenges:Currently reported cathode materials usually suffer from rapid capacity fading or high toxicity,and meanwhile,unstable zinc stripping/plating on Zn anode seriously shortens the cycling life of ZIBs.In this paper,metal-organic framework(MOF) materials are proposed to simultaneously address these issues and realize high-performance ZIB s with Mn(BTC) MOF cathodes and ZIF-8-coated Zn(ZIF-8@Zn) anodes.Various MOF materials were synthesized,and Mn(BTC) MOF was found to exhibit the best Zn^2+-storage ability with a capacity of 112 mAh g^-1.Zn^2+ storage mechanism of the Mn(BTC) was carefully studied.Besides,ZIF-8@Zn anodes were prepared by coating ZIF-8 MOF material on Zn foils.Unique porous structure of the ZIF-8 coating guided uniform Zn stripping/plating on the surface of Zn anodes.As a result,the ZIF-8@Zn anodes exhibited stable Zn stripping/plating behaviors,with 8 times longer cycle life than bare Zn foils.Based on the above,high-performance aqueous ZIBs were constructed using the Mn(BTC) cathodes and the ZIF-8@Zn anodes,which displayed an excellent long-cycling stability without obvious capacity fading after 900 charge/discharge cycles.This work provides a new opportunity for high-performance energy storage system.

Non‑Magnetic Bimetallic MOF‑Derived Porous Carbon‑Wrapped TiO2/ ZrTiO4 Composites for Efficient Electromagnetic Wave Absorption

Modern communication technologies put forward higher requirements for electromagnetic wave(EMW)absorption materials.Metal-organic framework(MOF)derivatives have been widely concerned with its diverse advantages.To break the mindset of magneticderivative design,and make up the shortage of monometallic non-magnetic derivatives,we first try non-magnetic bimetallic MOFs derivatives to achieve efficient EMW absorption.The porous carbon-wrapped TiO2/ZrTiO4 composites derived from PCN-415(TiZr-MOFs)are qualified with a minimum reflection loss of−67.8 dB(2.16 mm,13.0 GHz),and a maximum effective absorption bandwidth of 5.9 GHz(2.70 mm).Through in-depth discussions,the synergy of enhanced interfacial polarization and other attenuation mechanisms in the composites is revealed.Therefore,this work confirms the huge potentials of nonmagnetic bimetallic MOFs derivatives in EMW absorption applications.

ZIF-8-based micro-arc oxidation composite coatings enhanced the corrosion resistance and superhydrophobicity of a Mg alloy

Mg alloys are considered the most promising engineering materials because of their unique properties.However,the uncontrolled corrosion rate of these alloys limits their applications.Therefore,in this study,a micro-arc oxidation layer was used as a transition layer to“directly”grow a zinc-based metal-organic framework(MOF)composite coating on the surface of a Mg alloy(AZ91D).Herein,the two zeolitic imidazolate framework(ZIF-8)coatings with different morphologies were separately prepared by homologous metal oxide induction and a one-step in-situ growth method.The superhydrophobic composite coating showed strong hydrophobicity and self-cleaning properties,which could prevent the penetration of water and corrosive ions(Cl^(−))into the surface of AZ91D.Electrochemical tests demonstrated that the super-hydrophobic composite coatings greatly enhanced the corrosion resistance of AZ91D,and the corrosion current density decreased from 10^(−5)to 10^(−9)A/cm^(2).These results indicate that the ZIF-8 coatings are beneficial for improving the hydrophobicity and enhancing the corrosion resistance of Mg alloys.Therefore,MOF composite coatings provide a new strategy that can be used to prepare multifunctional anticorrosion coatings on metal substrates.