MOFs‑Derived Strategy and Ternary Alloys Regulation in Flower‑Like Magnetic‑Carbon Microspheres with Broadband Electromagnetic Wave Absorption

Broadband electromagnetic(EM)wave absorption materials play an important role in military stealth and health protection.Herein,metal–organic frameworks(MOFs)-derived magnetic-carbon CoNiM@C(M=Cu,Zn,Fe,Mn)microspheres are fabricated,which exhibit flower-like nano–microstructure with tunable EM response capacity.Based on the MOFs-derived CoNi@C microsphere,the adjacent third element is introduced into magnetic CoNi alloy to enhance EM wave absorption performance.In term of broadband absorption,the order of efficient absorption bandwidth(EAB)value is Mn>Fe=Zn>Cu in the CoNiM@C microspheres.Therefore,MOFs-derived flower-like CoNiMn@C microspheres hold outstanding broadband absorption and the EAB can reach up to 5.8 GHz(covering 12.2–18 GHz at 2.0 mm thickness).Besides,off-axis electron holography and computational simulations are applied to elucidate the inherent dielectric dissipation and magnetic loss.Rich heterointerfaces in CoNiMn@C promote the aggregation of the negative/positive charges at the contacting region,forming interfacial polarization.The graphitized carbon layer catalyzed by the magnetic CoNiMn core offered the electron mobility path,boosting the conductive loss.Equally importantly,magnetic coupling is observed in the CoNiMn@C to strengthen the magnetic responding behaviors.This study provides a new guide to build broadband EM absorption by regulating the ternary magnetic alloy.

Strong metal-support interactions between highly dispersed Cu^(+) species and ceria via mix-MOF pyrolysis toward promoted water-gas shift reaction

The modulation of metal-support interfacial interaction is significant but challenging in the design of high-efficiency and high-stability supported catalysts.Here,we report a synthetic strategy to upgrade Cu-CeO_(2)interfacial interaction by the pyrolysis of mixed metal-organic framework(MOF)structure.The obtained highly dispersed Cu/CeO_(2)-MOF catalyst via this strategy was used to catalyze water-gas shift reaction(WGSR),which exhibited high activity of 40.5μmolCOgcat^(-1).s^(-1)at 300℃and high stability of about 120 h.Based on comprehensive studies of electronic structure,pyrolysis strategy has significant effect on enhancing metal-support interaction and then stabilizing interfacial Cu^(+)species under reaction conditions.Abundant Cu^(+)species and generated oxygen vacancies over Cu/CeO_(2)-MOF catalyst played a key role in CO molecule activation and H2O molecule dissociation,respectively.Both collaborated closely and then promoted WGSR catalytic performance in comparison with traditio nal supported catalysts.This study shall offer a robust approach to harvest highly dispersed catalysts with finely-tuned metal-support interactions for stabilizing the most interfacial active metal species in diverse heterogeneous catalytic reactions.

Rational Design of MOF-Based Materials for Next-Generation Rechargeable Batteries

Metal–organic framework(MOF)-based materials with high porosity,tunable compositions,diverse structures,and versatile functionalities provide great scope for next-generation rechargeable battery applications.Herein,this review summarizes recent advances in pristine MOFs,MOF composites,MOF derivatives,and MOF composite derivatives for high-performance sodium-ion batteries,potassiumion batteries,Zn-ion batteries,lithium–sulfur batteries,lithium–oxygen batteries,and Zn–air batteries in which the unique roles of MOFs as electrodes,separators,and even electrolyte are highlighted.Furthermore,through the discussion of MOFbased materials in each battery system,the key principles for controllable synthesis of diverse MOF-based materials and electrochemical performance improvement mechanisms are discussed in detail.Finally,the major challenges and perspectives of MOFs are also proposed for next-generation battery applications.

Carbon-Based MOF Derivatives:Emerging Efficient Electromagnetic Wave Absorption Agents

To tackle the aggravating electromagnetic wave(EMW)pollution issues,high-efficiency EMW absorption materials are urgently explored.Metal-organic framework(MOF)derivatives have been intensively investigated for EMW absorption due to the distinctive components and structures,which is expected to satisfy diverse application requirements.The extensive developments on MOF derivatives demonstrate its significantly important role in this research area.Particularly,MOF derivatives deliver huge performance superiorities in light weight,broad bandwidth,and robust loss capacity,which are attributed to the outstanding impedance matching,multiple attenuation mechanisms,and destructive interference effect.Herein,we summarized the relevant theories and evaluation methods,and categorized the state-of-the-art research progresses on MOF derivatives in EMW absorption field.In spite of lots of challenges to face,MOF derivatives have illuminated infinite potentials for further development as EMW absorption materials.

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.

Metal‐organic framework‐derived multifunctional photocatalysts

Metal‐organic framework(MOF)‐derived nanomaterials have attracted widespread attention,because the excellent features,such as high surface area,porosity and tunable properties are inherited from MOFs.Moreover,the derivatives avoid the poor conductivity and stability of MOFs.MOF‐derived nanomaterials can easily be regulated by a specific selection of metal nodes and organic linkers,resulting in multifunctionality in photocatalysis.MOF derivatives can be used not only as semiconductor photocatalysts,but also as co‐catalysts for photocatalytic hydrogen evolution,CO_(2) reduction,pollutants degradation,etc.This review focuses on the multifunctional applications of MOF derivatives in the field of photocatalysis.The researches in recent years are analyzed and summarized from the aspects of preparation,modification and application of MOF derivatives.At the end of the review,the development and challenges of MOF derivatives applied in photocatalysis in the future are put forward,in order to provide more references for further research in this field and bring new inspiration.

Novel isostructural iron‐series‐MOF calcined derivatives as positive and negative electrodes: A new strategy to obtain matched electrodes in a supercapacitor device

The performance of asymmetric supercapacitors(ASCs)is strongly restricted by the capacity gap between the positive and negative electrodes.To address this issue,two new electrode materials deriving from Co‐and Fe‐based metal–organic frameworks(MOFs,Co‐TAMBA‐d,and Fe‐TAMBA‐d)through a single‐step sintering method have been developed by considering the superiorities of the derivatives of MOFs including large surface areas,sufficient metal‐atom‐doping content,and extreme surface wettability to the bath solution.The as‐prepared Co‐TAMBA‐d as a positive electrode delivers typical pseudocapacitive behavior with the improvement of capacity,which is better than those of pristine MOF materials,while Fe‐TAMBA‐d as negative electrodes displays better electrochemical behavior than those of activated carbon.ASCs based on these two electrodes exhibits excellent energy density and power density of 47Wh/kg and 1658 W/kg,respectively,where this device can maintain prominent cycling stability with capacity retention after 5000 cycles being about 75%.Furthermore,the capacity can feed a series of red light‐emitting diodes,which gives solid evidence of the potential utilization.These results can afford the feasibility of isostructural MOF derivatives as promising electrodes in novel ASCs.

Advanced MOF-based electrode materials for supercapacitors and electrocatalytic oxygen reduction

Metal-organic frameworks(MOFs)have attracted a lot of attention due to their diverse structures,favorable porous properties,and tunable chemical compositions in the multiple fields.Notably,MOF-based materials(including pristine MOFs,MOF composites,and their derivatives)play the vital role in electrochemical energy storage and conversion systems,due to their ability for regulating chemical composition at the molecular level and their highly porous frameworks for facilitating the mass and charge transfer.Supercapacitors and fuel cells are used as one of energy storage and conversion systems respectively,and it is unstoppable to design and synthesize high-efficiency electrode materials for them.This review starts with the strategies for designing targeted MOF-based materials in electrochemical energy storage and conversion applications followed by the state-ofthe-art MOF-based materials discussed as to their potential applications in supercapacitors and electrocatalytic oxygen reduction reaction(ORR).Finally,the challenges and perspectives of MOF-based materials applied for supercapacitors and electrocatalytic ORR are discussed.

In-MOF-derived In_(2)S_(3)/Bi_(2)S_(3) heterojunction for enhanced photocatalytic hydrogen production

Transition metal sulfides are commonly studied as photocatalysts for water splitting in solar-to-fuel conversion.However,the effectiveness of these photoca-talysts is limited by the recombination and restricted light absorption capacity of carriers.In this paper,a broad spectrum responsive In_(2)S_(3)/Bi_(2)S_(3)heterojunction is cons-tructed by in-situ integrating Bi_(2)S_(3)with the In_(2)S_(3),derived from an In-MOF precursor,via the high-temperature sulfidation and solvothermal methods.Benefiting from the synergistic effect of wide-spectrum response,effective charge separation and transfer,and strong heterogeneous interfacial contacts,the In_(2)S_(3)/Bi_(2)S_(3)heterojunction demons-trates a rate of 0.71 mmol/(g∙h),which is 2.2 and 1.7 times as much as those of In_(2)S_(3)(0.32 mmol/(g∙h))and Bi_(2)S_(3)(0.41 mmol/(g∙h)),respectively.This paper provides a novel idea for rationally designing innovative heterojunc-tion photocatalysts of transition metal sulfides for photocatalytic hydrogen production.

The synthesis of MOF derived carbon and its application in water treatment

In recent years,since water pollution has aroused great public concern,various carbon materials have already been widely applied for water treatment.In this respect,tremendous effort has been made to provide different synthesis methods of carbon materials.Among all carbon materials,metal-organic framework(MOF)derived carbon has always been favored as it possesses several appealing merits such as high specific surface area,large pore volume,and outstanding chemical stability.This review presents the latest development of MOFs as templates and precursors for the fabrication of various carbon materials,including porous carbon,nanocarbon,and graphene,which are pyrolyzed at different temperatures.The article also emphasizes on their future trends and perspectives on the application of water treatment.

Atomic regulations of single atom from metal-organic framework derived carbon for advanced water treatment

Single atom(SA)-embedded nitrogen-doped carbon has shown great potential in environmental remediation.Nowadays,engineered nanomaterials(ENMs)have attracted great research interests in recent years.Metal-organic framework(MOF)derived SAs show the advantages of tunable topology and averaged separated active sites.SAs bridge the gap between homogeneous and heterogeneous catalysts.The reaction efficiency can be significantly improved by designing the MOFs derived from carbon and SAs.In this review,the research advanced in MOFs-derived carbon and SAs in advanced oxidation process(AOP)in water were summarized.Major strategies to fabricate the SAs derived from MOFs were discussed,including the mixed/single metal strategy,metal-containing linker strategy,pore confinement strategy,thermal diffusion strategy,and pyrolysis MOFs with bulk metals.Advanced characterization technologies have been introduced,including electron microscopy and spectroscopic methods.To explain the catalytic mechanism for various applications,the relationship between the performance and the atomic configuration was systematically discussed.Recent applications of the MOFs derived from carbon and SAs have been summarized.A series of the latest work on effectively removing pollutants by SAs are also listed.Based on the fundamental knowledge and recent practical application of MOFs-derived carbon and SAs,some perspectives on the further directions were presented.This review offers guidance for applying novel engineered nanomaterials in the water treatment field.

Low-dimensional cobalt doped carbon composite towards wideband electromagnetic dissipation

Composites composed of a carbon matrix decorated with a metal or metal oxide derived from zeolitic imidazolate frameworks(ZIFs)have been widely applied as suitable electromagnetic wave absorbers due to their high porosity and controllable morphology.However,achieving ideal absorption performance remains a challenge owing to the inadequate conductivity and high density of the metal components.Therefore,a temperature-controlling treatment was employed for the bimetal ZIFs,and the corresponding derivatives exhibited an excellent dissipation ability with a minimum reflection loss value of−54.3 dB and an effective bandwidth of 7.0 GHz at a thickness of 2.4 mm,which resulted from the strong dipole polarization behavior.Furthermore,after successfully controlling the Zn/Co ratio,the attenuation capability was greatly enhanced at a thickness of 1.4 mm,with bandwidths of 13.0–18.0 GHz.Overall,this work provides an ameliorated strategy for microwave absorption performance of carbon-based materials.

Accelerating water dissociation at carbon supported nanoscale Ni/NiO heterojunction electrocatalysts for high-efficiency alkaline hydrogen evolution

The synergistic catalysis of heterojunction electrocatalysts for the multi-step process in hydrogen evolution reaction(HER)is a promising approach to enhance the kinetics of alkaline HER.Herein,we proposed a strategy to form nanoscale Ni/NiO heterojunction porous graphitic carbon composites(Ni/NiO-PGC)by reduction-pyrolysis of the preformed Ni-metal-organic framework(MOF)under H2/N2 atmosphere.Benefiting from low electron transfer resistance,increased number of active sites,and unique hierarchical micro-mesoporous structure,the optimized Ni/NiO-PGC_(10-1-400)exhibited excellent electrocatalytic performance and robust stability for alkaline HER(η10=30 mV,65 h).Density functional theory(DFT)studies revealed that the redistribution of electrons at the Ni/NiO interface enables the NiO phase to easily initiate the dissociation of alkaline H_(2)O,and shifts down the d-band center of Ni and optimizes the H*adsorption-desorption process of Ni,thereby leading to extremely high HER activity.This work contributes to a further understanding of the synergistic promotion of the multi-step HER processes by heterojunction electrocatalysts.

Metal-organic framework derived multi-functionalized and co-doped TiO_(2)/C nanocomposites for excellent visible-light photocatalysis

Multi-functionalized and co-doped TiO_(2)/C nanocomposites were derived from the pyrolysis of Ti-MOFs at 800℃under different gaseous atmospheres and their photocatalytic performance were investigated.The gaseous atmosphere during pyrolysis plays a critical role in determining the structural,textural,optical and physicochemical properties of the derived TiO_(2)/C composites due to the synergistic effect of nitrogen-containing species,carboxylate and sulfur functionalized porous carbon as well as N/S co-doped TiO_(2)nanoparticles.All the Ti-MOFs derived TiO_(2)/C composites exclusively possess homogeneously distributed TiO_(2)nanoparticles in a functionalized disc-like porous carbon matrix and demonstrate much enhanced adsorption and photodegradation performance than commercial TiO_(2)under the same conditions.The adsorption of methylene blue(MB)in dark on these TiO_(2)/C composites are dominated with pseudo second-order kinetic model and the high adsorption capacity of MB in dark on composite TiO_(2)/C derived from MIL-125(Ti)in argon is due to its high surface area with predominant mesoporous carbon matrix in the composite.The composite N-O-TiO_(2)/C derived from NH2-MIL-125(Ti)in water vapor exhibited the highest photodegradation activity with 99.7%MB removal in 3 h under visible light due to the optimal anatase/rutile phasejunction,together with the formation of photoactive oxygen-rich N-O like interstitial/intraband states above the valence band of TiO_(2),as well as the presence of N-containing species and-OH/-COOH multi-functional groups with superhydrophilic nature of the composite.This simple one-step and easily modifiable approach can be further employed to modulate homogeneously dispersed multi-functionalized and co-doped metal oxide/carbon nanocomposites for various environment and energy-related applications.

Confined Pyrolysis Synthesis of Well-dispersed Cobalt Copper Bimetallic Three-dimensional N-Doped Carbon Framework as Efficient Water Splitting Electrocatalyst

Hydrogen is one of the most desirable alternatives to fossil fuels due to its renewability and large energy density.Electrochemical water splitting,as an environmental-friendly way to produce H_(2) of high-purity,is drawing more and more attention.Conductive nitrogen-doped carbon frameworks derived from metal-organic frameworks(MOFs)have been applied as promising electrocatalysts thanks to their superior conductivity,numerous active sites and hierarchical porous structures.However,traditional uncontrolled pyrolysis will lead to aggregation or fusion of the metal sites in MOFs or even cause collapse of the three-dimensional structures.Herein,we provide a confinement pyrolysis strategy to fabricate a CoCu bimetallic N-doped carbon framework derived from MOFs,which exhibits satisfactory catalytic performance with overpotentials of 199 mV towards hydrogen evolution reaction and 301 mV towards oxygen evolution reaction to reach 10 mA/cm^(2) in an alkaline solution.This work presents further inspirations for preserving the original skeleton of MOFs during high temperature pyrolysis in order to obtain more stable and efficient electrocatalyst.

Carbon-supported layered double hydroxide nanodots for efficient oxygen evolution: Active site identification and activity enhancement

In this study,we developed a novel confinement-synthesis approach to layered double hydroxide nanodots(LDH-NDs)anchored on carbon nanoparticles,which formed a three-dimensional(3D)interconnected network within a porous carbon support derived from pyrolysis of metal-organic frameworks(C-MOF).The resultant LDH-NDs@C-MOF nonprecious metal catalysts were demonstrated to exhibit super-high catalytic performance for oxygen evolution reaction(OER)with excellent operation stability and low overpotential(-230 mV)at an exchange current density of 10 mA·cm^(-2).The observed overpotential for the LDH-NDs@C-MOF is much lower than that of large-sized LDH nanosheets(321 mV),pure carbonized MOF(411 mV),and even commercial RuO_(2)(281 mV).X-ray absorption measurements and density functional theory(DFT)calculations revealed partial charge transfer from Fe^(3+)through an O bridge to Ni^(2+)at the edge of LDH-NDs supported by C-MOF to produce the optimal binding energies for OER intermediates.This,coupled with a large number of exposed active sides and efficient charge and electrolyte/reactant/product transports associated with the porous 3D C-MOF support,significantly boosted the OER performance of the LDH-ND catalyst with respect to its nanosheet counterpart.Apart from the fact that this is the first active side identification for LDH-ND OER catalysts,this work provides a general strategy to enhance activities of nanosheet catalysts by converting them into edge-rich nanodots to be supported by 3D porous carbon architectures.

Metal–Organic Frameworks and Their Derivatives as Cathodes for Lithium‑Ion Battery Applications:A Review

The development of energy storage technology is important for resolving the issues and challenges of utilizing sustainable green energy in modern-day society.As an emerging technology,lithium-ion batteries(LIBs)are a common source of power for a wide variety of electronic devices,and major advances require the development and exploitation of new electrode materials;thus,fundamental knowledge of their atomic and nanoscale properties is necessary.By moving beyond conven-tional cathode candidates,metal–organic frameworks(MOFs)chemistry provides an excellent direction for designing and developing promising high-performance cathode materials for use in LIBs.Here,we carry out an overarching discussion on the development and application of MOFs and their derivatives as cathodes for lithium-ion battery applications.A timely overview of the exciting progress of MOFs as well as MOF-derived metallic components is highlighted.The unique char-acteristics of MOFs,such as their large surface area,high tunable porosity with uniform pore size,unique structural and morphological features,controllable framework composition and low densities,combine together to provide good interfacial charge transport properties and short diffusion lengths for electrons and/or ions that adequately support electrochemical redox reactions.The progress of MOFs and their derived composites as cathode candidates for LIBs is emphasized based on their electrochemical results,while also discussing the remaining issues and potential upcoming research directions.

Novel strategies to tailor the photocatalytic activity of metal–organic frameworks for hydrogen generation: a mini-review

This review provides a recompilation of the most important and recent strategies employed to increase the efficiency of metal-organic framework(MOF)-based systems toward the photocatalytic hydrogen evolution(PHE)reaction through specific strategies:tailoring the photocatalytic activity of bare MOFs and guest@MOF composites,formation of heterojunctions based on MOFs and various photocatalysts,and inorganic photocatalysts derived from MOFs.According to the data reported in this mini-review,the most effective strategy to improve the PHE of MOFs relies on modifying the linkers with new secondary building units(SBUs).Although several reviews have investigated the photocatalytic activity of MOFs from a general point of view,many of these studies relate this activity to the physicochemical and catalytic properties of MOFs.However,they did not consider the interactions between the components of the photocatalytic material.This study highlights the effects of strength of the supramolecular interactions on the photocatalytic performance of bare and MOF-based materials during PHE.A thorough review and comparison of the results established that metal-nanoparticle@MOF composites have weak van der Waals forces between components,whereas heterostructures only interact with MOFs at the surface of bare materials.Regarding material derivatives from MOFs,we found that pyrolysis destroyed some beneficial properties of MOFs for PHE.Thus,we conclude that adding SBUs to organic linkers is the most efficient strategy to perform the PHE because the SBUs added to the MOFs promote synergy between the two materials through strong coordination bonds.

Graphene-reinforced metal-organic frameworks derived cobalt sulfide/carbon nanocomposites as efficient multifunctional electrocatalysts

Developing cost-effective electrocatalysts for oxygen reduction reaction(ORR),oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)is vital in energy conversion and storage applications.Herein,we report a simple method for the synthesis of graphene-reinforced CoS/C nanocomposites and the evaluation of their electrocatalytic performance for typical electrocatalytic reactions.Nanocomposites of CoS embedded in N,S co-doped porous carbon and graphene(CoS@C/Graphene)were generated via simultaneous sulfurization and carbonization of one-pot synthesized graphite oxide-ZIF-67 precursors.The obtained CoS@C/Graphene nanocomposites were characterized by X-ray diffraction,Raman spectroscopy,thermogravimetric analysis-mass spectroscopy,scanning electronic microscopy,transmission electronic microscopy,X-ray photoelectron spectroscopy and gas sorption.It is found that CoS nanoparticles homogenously dispersed in the in situ formed N,S co-doped porous carbon/graphene matrix.The CoS@C/10Graphene composite not only shows excellent electrocatalytic activity toward ORR with high onset potential of 0.89 V,four-electron pathway and superior durability of maintaining 98%of current after continuously running for around 5 h,but also exhibits good performance for OER and HER,due to the improved electrical conductivity,increased catalytic active sites and connectivity between the electrocatalytic active CoS and the carbon matrix.This work offers a new approach for the development of novel multifunctional nanocomposites for the next generation of energy conversion and storage applications.