Metal-organic frameworks and their composites for advanced lithium-ion batteries:Synthesis,progress and prospects

Metal-organic frameworks(MOFs)are among the most promising materials for lithium-ion batteries(LIBs)owing to their high surface area,periodic porosity,adjustable pore size,and controllable chemical composition.For instance,their unique porous structures promote electrolyte penetration,ions transport,and make them ideal for battery separators.Regulating the chemical composition of MOF can introduce more active sites for electrochemical reactions.Therefore,MOFs and their related composites have been extensively and thoroughly explored for LIBs.However,the reported reviews solely include the applications of MOFs in the electrode materials of LIBs and rarely involve other aspects.A systematic review of the application of MOFs in LIBs is essential for understanding the mechanism of MOFs and better designing related MOFs battery materials.This review systematically evaluates the latest developments in pristine MOFs and MOF composites for LIB applications,including MOFs as the main materials(anode,cathode,separators,and electrolytes)to auxiliary materials(coating layers and additives for electrodes).Furthermore,the synthesis,modification methods,challenges,and prospects for the application of MOFs in LIBs are discussed.

Synergistic catalysis of the N-hydroxyphthalimide on flower-like bimetallic metal-organic frameworks for boosting oxidative desulfurization

Synergic catalytic effect between active sites and supports greatly determines the catalytic activity for the aerobic oxidative desulfurization of fuel oils.In this work,Ni-doped Co-based bimetallic metal-organic framework(CoNi-MOF)is fabricated to disperse N-hydroxyphthalimide(NHPI),in which the whole catalyst provides plentiful synergic catalytic effect to improve the performance of oxidative desulfurization(ODS).As a bimetallic MOF,the second metal Ni doping results in the flower-like morphology and the modification of electronic properties,which ensure the exposure of NHPI and strengthen the synergistic effect of the overall catalyst.Compared with the monometallic Co-MOF and naked NHPI,the NHPI@CoNi-MOF triggers the efficient activation of molecular oxygen and improves the ODS performance without an initiator.The sulfur removal of dibenzothiophene-based model oil reaches 96.4%over the NHPI@CoNi-MOF catalyst in 8 h of reaction.Furthermore,the catalytic product of this aerobic ODS reaction is sulfone,which is adsorbed on the catalyst surface due to the difference in polarity.This work provides new insight and strategy for the design of a strong synergic catalytic effect between NHPI and bimetallic supports toward high-activity aerobic ODS materials.

Photophysics of metal-organic frameworks:A brief overview

Metal-organic frameworks(MOFs),which are self-assembled porous coordination materials,have garnered considerable attention in the fields of optoelectronics,photovoltaic,photochemistry,and photocatalysis due to their diverse structures and excellent tunability.However,the performance of MOF-based optoelectronic applications currently falls short of the industry benchmark.To enhance the performance of MOF materials,it is imperative to undertake comprehensive investigations aimed at gaining a deeper understanding of photophysics and sequentially optimizing properties related to photocarrier transport,recombination,interaction,and transfer.By utilizing femtosecond laser pulses to excite MOFs,time-resolved optical spectroscopy offers a means to observe and characterize these ultrafast microscopic processes.This approach adds the time coordinate as a novel dimension for comprehending the interaction between light and MOFs.Accordingly,this review provides a comprehensive overview of the recent advancements in the photophysics of MOFs and additionally outlines potential avenues for exploring the time domain in the investigation of MOFs.

Regulating interfacial behavior of zinc metal anode via metal-organic framework functionalized separator

Aqueous zinc ion batteries(AZIBs)are one of the promising energy storage devices.However,uncontrolled dendrite and side reactions have seriously hindered its further application.In this study,the metal-organic framework(MOF)functionalized glass fiber separator(GF-PFC-31)was used to regulate interfacial behavior of zinc metal anode,enabling the development of high-performance AZIBs.In PFC-31,there areπ-πinteractions between two adjacent benzene rings with a spacing of 3.199 A.This spacing can block the passage of[Zn(H_(2)O)_6]^(2+)(8.6 A in diameter)through the GF-PFC-31 separator to a certain extent,which promotes the deposition process of Zn ions.In addition,the sulfonic acid group(-S03H)contained in GF-PFC-31 can form a hydrogen bonding network with H_(2)O,which can provide a desolvation effect and reduce the side reaction.Consequently,GF-PFC-31 separator achieves uniform deposition of Zn ions.The Zn‖GF-PFC-31‖Zn symmetric cell exhibits stable cycle life(3000 h at 1.2 mA cm^(-2),2000 h at 0.3 mA cm^(-2),and 2000 h at 5.0 mA cm^(-2)),and Zn‖GF-PFC-31‖MnO_(2) full cell with GF-PFC-31 separator can cycle for 1000 cycles at 1.2 A g^(-1)with capacity retention rate of 82.5%.This work provides a promising method to achieve high-performance AZIBs.

Research progress on the substrate for metal-organic framework(MOF) membrane growth for separation

During the last decade, metal-organic frameworks(MOFs) have been applied in various fields due to their unique chemical and functional advantages. One of the widespread research hotspots is MOF-based membranes for separations, specifically continuous defect-free MOF membranes, which are usually grown on porous substrates. The substrate not only serves as the MOF layer support but also has a great influence on the membrane fabrication process and the final separation performance of the resultant membrane. In this review, we mainly introduce the progress focused on the substrates for MOF membranes fabrication. The substrate modifications and seeding methods aimed at synthesizing highquality MOF membranes are also summarized systematically.

Dual-conductive metal-organic framework@MXene heterogeneity stabilizes lithium-ion storage

Although a few pristine metal-organic frameworks(MOFs) of graphene analogue topology exhibit high intrinsic electrical conductivity, their use in lithium-ion batteries(LIBs) is still hampered by unfavorable Li+adsorption energy(ΔEa). In this paper, an electroconductive ferrocene-based MOF@MXene heterostructure is built to provide stable anodes for Li+storage. Charge density difference and planar average potential charge density show substantial redistribution of charges at the interfaces, transferring from MXene to MOF layers. Moreover, density functional theory(DFT) calculations reveal that the interaction between MXene and MOF significantly increases the ΔEa. As a result, the heterostructure anode exhibits high capacities and outstanding cycling stability with a capacity retention of 80% after 5000 cycles at 5 A g^(-1), outperforming mono-component MXene and MOF. Furthermore, the heterostructure anode is built into a full cell with a commercial NCM 532 cathode, delivering a high energy density of 611 Wh kg^(-1)and power density of 7600 W kg^(-1). The developed conductive MOF@MXene heterogeneity for improved LIB offers valuable insights into the design of advanced electrode materials for energy storage.

Structural survey of metal-covalent organic frameworks and covalent metal-organic frameworks

This review offers an overview of the latest developments in metal-covalent organic framework(MCOF)and covalent metal-organic framework(CMOF)materials,whose construction entails a combination of reversible coordination and covalent bonding adapted from metal-organic frameworks(MOFs)and covalent organic frameworks(COFs),respectively.With an emphasis on the MCOF and CMOF structures,this review surveys their building blocks and topologies.Specifically,the frameworks are classified based on the dimensions of their components(building blocks),namely,discrete building blocks and one-dimensional infinite building blocks.For the first category,the materials are further divided into collections of two-and three-dimensional networks based on their topologies.For the second category,the recently emerging MCOFs with woven structures are covered.Finally,the state-of-the-art in MCOF and CMOF chemistry has been laid out for promising avenues in future developments.

Engineering Spin States of Isolated Copper Species in a Metal-Organic Framework Improves Urea Electrosynthesis

The catalytic activities are generally believed to be relevant to the electronic states of their active center, but understanding this relationship is usually difficult. Here, we design two types of catalysts for electrocatalytic urea via a coordination strategy in a metal–organic frameworks: Cu^(Ⅲ)-HHTP and Cu^(Ⅱ)-HHTP. Cu^(Ⅲ)-HHTP exhibits an improved urea production rate of 7.78 mmol h^(−1)g^(−1) and an enhanced Faradaic efficiency of 23.09% at-0.6 V vs. reversible hydrogen electrode, in sharp contrast to Cu^(Ⅱ)-HHTP.Isolated CuⅢspecies with S = 0 spin ground state are demonstrated as the active center in Cu^(Ⅲ)-HHTP, different from Cu^(Ⅱ) with S = 1/2 in Cu^(Ⅱ)-HHTP. We further demonstrate that isolated Cu^(Ⅲ)with an empty dx2-y20orbital in Cu^(Ⅲ)-HHTP experiences a single-electron migration path with a lower energy barrier in the C–N coupling process, while Cu^(Ⅱ)with a single-spin state( d_(x2-y2)^(1)) in Cu^(Ⅱ)-HHTP undergoes a two-electron migration pathway.

Tuning the electronic structure of a metal-organic framework for an efficient oxygen evolution reaction by introducing minor atomically dispersed ruthenium

The establishment of efficient oxygen evolution electrocatalysts is of great value but also challenging.Herein,a durable metal–organic framework(MOF)with minor atomically dispersed ruthenium and an optimized electronic structure is constructed as an efficient electrocatalyst.Significantly,the obtained NiRu_(0.08)-MOF with doping Ru only needs an overpotential of 187 mV at 10 mA cm^(-2) with a Tafel slop of 40 mV dec^(-1) in 0.1M KOH for the oxygen evolution reaction,and can work continuously for more than 300 h.Ultrahigh Ru mass activity is achieved,reaching 56.7 Ag^(-1)_(Ru) at an overpotential of 200 mV,which is 36 times higher than that of commercial RuO_(2).X-ray adsorption spectroscopy and density function theory calculations reveal that atomically dispersed ruthenium on metal sites in MOFs is expected to optimize the electronic structure of nickel sites,thus improving the conductivity of the catalyst and optimizing the adsorption energy of intermediates,resulting in significant optimization of electrocatalytic performance.This study could provide a new avenue for the design of efficient and stable MOF electrocatalysts.

One-step ethylene separation from ternary C_(2) hydrocarbon mixture with a robust zirconium metal-organic framework

One-step separation of high-purity ethylene(C_(2)H_(4))from C_(2) hydrocarbon mixture is critical but challenging because of the very similar molecular sizes and physical properties of C_(2)H_(4),ethane(C_(2)H_(6)),and acetylene(C_(2)H_(2)).Herein,we report a robust zirconium metal-organic framework(MOF)Zr-TCA(H3TCA=4,4',4"-tricarboxytriphenylamine)with suitable pore size(0.6 nm×0.7 nm)and pore environment for direct C_(2)H_(4) purification from C_(2)H_(4)/C_(2)H_(2)/C_(2)H_(6) gas-mixture.Computational studies indicate that the abundant oxygen atoms and non-polar phenyl rings created favorable pore environments for the preferential binding of C_(2)H_(2) and C_(2)H_(6) over C_(2)H_(4).As a result,Zr-TCA exhibits not only high C_(2)H_(6)(2.28 mmol·g^(-1))and C_(2)H_(2)(2.78 mmol·g^(-1))adsorption capacity but also excellent C_(2)H_(6)/C_(2)H_(4)(2.72)and C_(2)H_(2)/C_(2)H_(4)(5.64)selectivity,surpassing most of one-step C_(2)H_(4) purification MOF materials.Dynamic breakthrough experiments confirm that Zr-TCA can produce high-purity C_(2)H_(4)(>99.9%)from a ternary gas mixture(1/9/90 C_(2)H_(2)/C_(2)H_(6)/C_(2)H_(4))in a single step with a high C_(2)H_(4) productivity of 5.61 L·kg^(-1).

Metal-organic frameworks based single-atom catalysts for advanced fuel cells and rechargeable batteries

The next-generation energy storage systems such as fuel cells,metal-air batteries,and alkali metal(Li,Na)-chalcogen(S,Se)batteries have received increasing attention owing to their high energy density and low cost.However,one of the main obstacles of these systems is the poor reaction kinetics in the involved chemical reactions.Therefore,it is essential to incorporate suitable and efficient catalysts into the cell.These years,single-atom catalysts(SACs)are emerging as a frontier in catalysis due to their maximum atom efficiency and unique reaction selectivity.For SACs fabrication,metal-organic frameworks(MOFs)have been confirmed as promising templates or precursors due to their high metal loadings,structural adjustability,porosity,and tailorable catalytic site.In this review,we summarize effective strategies for fabricating SACs by MOFs with corresponding advanced characterization techniques and illustrate the key role of MOFs-based SACs in these batteries by explaining their reaction mechanisms and challenges.Finally,current applications,prospects,and opportunities for MOFs-based SACs in energy storage systems are discussed.

Metal-organic framework-based materials as key components in electrocatalytic oxidation and reduction reactions

Studies have extensively addressed the development of electrocatalytic technologies for energy storage and conversion,fuel production,and environmental protection.Electrode processes such as different oxidation and reduction reactions play a vital and significant role in these technologies.In this regard,efficient,inexpensive,and stable electrocatalysts capable can significantly promote electrochemical reactions.Unique features of metal–organic frameworks(MOFs)such as their high porosity,tunable structure,size,and pore shape,high surface area,and redox properties have introduced them as an ideal electrocatalyst candidate.This review is thus aimed at elucidating the role of MOF-based materials(pristine,derivatives and composites)as efficient electrocatalysts in energy and sensing-related oxidation and reduction reactions such as oxygen reduction reaction(ORR),hydrogen oxidation reaction(HOR),carbon dioxide reduction reaction(CO_(2)RR),urea oxidation reaction(UOR),alcohol oxidation reaction(AOR),nitrogen reduction reaction(NRR),and glucose oxidation reaction(GOR)in advanced energy and sensing devices.Also,the structure–property relationship of the electrocatalyst was elaborated for each electrocatalytic reaction.Finally,perspectives on the potential research topics for practical use of MOF-based electrocatalysts are addressed.The present review can improve the interest in MOF-based electrocatalysts to study different oxidation and reduction reactions in energy and sensing systems.

Recent Progress of Conductive Metal-Organic Frameworks for Electrochemical Energy Storage

The development of reliable and low-cost energy storage systems is of considerable value in using renewable and clean energy sources,and exploring advanced electrodes with high reversible capacity,excellent rate performance,and long cycling life for Li/Na/Zn-ion batteries and supercapacitors is the key problem.Particularly because of their diverse structure,high specific surface area,and adjustable redox activity,electrically conductive metal-organic frameworks(c-MOFs)are considered promising candidates for these electrochemical applications,and a detailed overview of the recent progress of c-MOFs for electrochemical energy storage and their intrinsic energy storage mechanism helps realize a comprehensive and systematic understanding of this progress and further achieve highly efficient energy storage and conversion.Herein,the chemical structure of c-MOFs and their conductive mechanism are first introduced.Subsequently,a comprehensive summarization of the current applications of c-MOFs in energy storage systems,namely supercapacitors,LIBs,SIBs,and ZIBs,is presented.Finally,the prospects and challenges of c-MOFs toward much higher-performance energy storage devices are presented,which should illuminate the future scientific research and practical applications of c-MOFs in energy storage fields.

Zinc-Based Metal-Organic Frameworks for High-Performance Supercapacitor Electrodes:Mechanism Underlying Pore Generation

Heat treatment of metal-organic frameworks(MOFs)has provided a wide variety of functional carbons coordinated with metal compounds.In this study,two kinds of zinc-based MOF(ZMOF),C_(16)H_(10)O_(4)Zn(ZMOF1)and C_(8)H_(4)O_(4)Zn(ZMOF2),were prepared.ZMOF1 and ZMOF2 were carbonized at 1000℃,forming CZMOF1 and CZMOF2,respectively.The specific surface area(S_(BET))of CZMOF2 was~2700 m^(2)g^(−1),much higher than that of CZMOF1(~1300 m^(2)g^(−1)).A supercapacitor electrode based on CZMOF2 achieved specific capacitances of 360,278,and 221 F g^(−1)at 50,250,and 1000 mA g^(−1)in an aqueous electrolyte(H2SO_(4)),respectively,the highest values reported to date for ZMOF-derived electrodes under identical conditions.The practical applicability of the CZMOF-based supercapacitor was verified in non-aqueous electrolytes.The initial capacitance retention was 78%after 100000 charge/discharge cycles at 10 A g^(−1).Crucially,the high capacitance of CZMOF2 arises from pore generation during carbonization.Below 1000℃,pore generation is dominated by the Zn/C ratio of ZMOFs,as carbon atoms reduce the zinc oxides formed during carbonization.Above 1000℃,a high O/C ratio becomes essential for pore generation because the oxygen functional groups are pyrolyzed.These findings will provide insightful information for other metal-based MOFderived multifunctional carbons.

Novel in-capsule synthesis of metal-organic framework for innovative carbon dioxide capture system

Metal-Organic Frameworks(MOFs)have been developed as solid sorbents for CO_(2) capture applications and their properties can be controlled by tuning the chemical blocks of their crystalline units.A number of MOFs(e.g.,HKUST-1)have been developed but the question remains how to deploy them for gas-solid contact.Unfortunately,the direct use of MOFs as nanocrystals would lead to serious problems and risks.Here,for the first time,we report a novel MOF-based hybrid sorbent that is produced via an innovative in-situ microencapsulated synthesis.Using a custom-made double capillary microfluidic assembly,double emulsions of the MOF precursor solutions and UV-curable silicone shell fluid are produced.Subsequently,HKUST-1 MOF is successfully synthesized within the droplets enclosed in the gas permeable microcapsules.The developed MOF-bearing microcapsules uniquely allow the deployment of functional nanocrystals without the challenge of handling ultrafine particles,and further,can selectively reject undesired compounds to protect encapsulated MOFs.

A chiral metal-organic framework{(HQA)(ZnCl_(2))(2.5H_(2)O)}n for the enantioseparation of chiral amino acids and drugs

Chiral metal-organic frameworks(CMOFs)with enantiomeric subunits have been employed in chiral chemistry.In this study,a CMOF formed from 6-methoxyl-(8S,9R)-cinchonan-9-ol-3-carboxylic acid(HQA)and ZnCl_(2),{(HQA)(ZnCl_(2))(2.5H_(2)O)}n,was constructed as a chiral stationary phase(CSP)via an in situ fabrication approach and used for chiral amino acid and drug analyses for the first time.The{(HQA)(ZnCl_(2))(2.5H_(2)O)}n nanocrystal and the corresponding chiral stationary phase were systematically characterised using a series of analytical techniques including scanning electron microscopy,X-ray diffraction,Fourier transform infrared spectroscopy,circular dichroism,X-ray photoelectron spectroscopy,thermogravimetric analysis,and Brunauer-Emmett-Teller surface area measurements.In opentubular capillary electrochromatography(CEC),the novel chiral column exhibited strong and broad enantioselectivity toward a variety of chiral analytes,including 19 racemic dansyl amino acids and several model chiral drugs(both acidic and basic).The chiral CEC conditions were optimised,and the enantioseparation mechanisms are discussed.This study not only introduces a new high-efficiency member of the MOF-type CSP family but also demonstrates the potential of improving the enantioselectivities of traditional chiral recognition reagents by fully using the inherent characteristics of porous organic frameworks.

Metal-organic framework derived NiFe_(2)O_(4)/FeNi_(3)@C composite for efficient electrocatalytic oxygen evolution reaction

Reducing the cost and improving the electrocatalytic activity are the key to developing high efficiency electrocatalysts for oxygen evolution reaction(OER).Here,bimetallic NiFe-based metal-organic framework(MOF)was prepared by solvothermal method,and then used as precursor to prepare NiFe-based MOF-derived materials by pyrolysis.The effects of different metal ratios and pyrolysis temperatures on the sample structure and OER electrocatalytic performance were investigated and compared.The experimental results showed that when the metal molar ratio was Fe:Ni=1:5 and the pyrolysis temperature was 450℃,the sample(FeNi_(5)-MOF-450)exhibits a composite structure of Ni Fe_(2)O_(4)/FeNi_(3)/C and owns the superior electrocatalytic activity in OER.When the current density is 100 mA·cm^(-2),the overpotential of the sample was 377 mV with Tafel slope of 56.2 mV·dec^(-1),which indicates that FeNi_(5)-MOF-450 exhibits superior electrocatalytic performance than the commercial RuO_(2).Moreover,the long-term stability of FeNi_(5)-MOF-450 further promotes its development in OER.This work demonstrated that the regulatory methods such as component optimization can effectively improve the OER catalytic performance of NiFe-based MOF-derived materials.

Trimetallic Metal-Organic Framework Nanoframe Superstructures: A Stress-Buffering Architecture Engineering of Anode Material toward Boosted Lithium Storage Performance

Metal-organic frameworks(MOFs)can serve as prevailing anodes for lithium-ion batteries,due to their multiple redox-active sites and prominent structural compatibility.However,the poor electronic conductivity and inferior cyclability hinder their further implementation.Herein,a synthetic methodology for trimetallic Fe-Co-Ni MOFs with nanoframe superstructures architecture(Fe-Co-Ni NFSs)via structural evolution is proposed for versatile anode materials for lithium storage.Ascribed to optimal compositional and structural optimization,the Fe-Co-Ni NFSs achieve exceptional electrochemical performance with superior specific capacity(1030 mAh g^(−1) at 0.1 A g^(−1)),outstanding rate capacity(414 mAh g^(−1) at 2 A g^(−1)),and prolonged cyclability(489 mAh g^(−1) upon 1000 cycles at 1 A g^(−1)).Both experimental and theoretical investigations reveal that the multi-component metal centers could boost electronic conductivity,confer multiple active sites,and energetically favor Li adsorption capability.Additionally,the nanoframe superstructures of Fe-Co-Ni NFSs could facilitate stress-buffering effect on volumetric expansion and prevent electrode pulverization,further improving the lithium storage capability.This work envisions a meticulous protocol for high-performance MOF anode materials for lithium-ion batteries.

Water-based synthesis of nanoscale hierarchical metal-organic frameworks:Boosting adsorption and catalytic performance

The combination of nano sizes,large pore sizes and green synthesis is recognized as one of the most crucial and challenging problems in constructing metal-organic frameworks(MOFs).Herein,a water-based strategy is proposed for the synthesis of nanoscale hierarchical MOFs(NH-MOFs)with high crystallinity and excellent stability.This approach allows the morphology and porosity of MOFs to be fine tuned,thereby enabling the nanoscale crystal generation and a well-defined hierarchical system.The aqueous solution facilitates rapid nucleation kinetics,and the introduced modulator acts as a deprotonation agent to accelerate the deprotonation of the organic ligand as well as a structure-directing agent(SDA)to guide the formation of hierarchical networks.The assynthesized NH-MOFs(NH-ZIF-67)were assessed as efficient adsorbents and heterogeneous catalysts to facilitate the diffusion of guest molecules,outperforming the parent microZIF-67.This study focuses on understanding the NH-MOF growth rules,which could allow tailor-designing NH-MOFs for various functions.

Metal-organic-frameworks passivated CuBi_(2)O_(4)photocathodes boost CO_(2)reduction kinetics

Photoelectrochemical reduction of CO_(2)to produce CO with metal-organic frameworks(MOFs)is recognized as a desirable technology to mitigate CO_(2)emission and generate sustainable energy.To achieve highly efficient electrocatalyst,it is essential to design a new material interface and uncover new reaction mechanisms or kinetics.Herein,we developed two metal-organic Cu-MOF and Bi-MOF layers using benzene tricarboxylic acid(H_(3)BTC)ligands on CuBi_(2)O_(4) photocathodes.Both MOF layers drastically improved the photoelectrochemical stability by suppressing the photo-corrosion through conformal surface passivation.The Cu-MOF modified CuBi_(2)O_(4) showed more significant charge separation and transfer efficiencies than the Bi-MOF modified control.Based on the transient photocurrent curves under the applied potential of 0.6 V vs.RHE,the rate-law analysis showed the CO_(2)photoreduction took place through a first-order reaction.Further,the photoelectrochemical impedance spectra(PEIS)revealed this reaction order,representing an“operando”analysis.Moreover,the reaction rate constant on Cu-MOF modified sample was higher than that on Bi-MOF modified one and bare CuBi_(2)O_(4).Combined with the density functional theory calculation,the surface absorption of CO_(2)and CO molecules and the higher energy barrier for*COOH intermediates could significantly determine the first order reaction.