Recent advances and perspectives of metal/covalent-organic frameworks in metal-air batteries

Metal-air batteries(MABs)have attracted considerable attention as a novel energy technology that can alleviate the severe energy crisis and environmental pollution.Two primary processes,including oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)occur on the air cathode and dominate the battery performance during battery charging and discharging.Recently,metal-organic frameworks(MOFs)and covalent-organic frameworks(COFs)emerge as promising cathode catalysts due to their structure and composition superiority.The unique characteristics of MOFs and COFs contribute to improved performance.This review mainly summarizes the recent applications of MOFs and COFs in a series of MABs,mainly including lithium-and zinc-air batteries.Additionally,some critical issues are emphasized regarding MOFs and COFs used in other MABs limited progress,their fabrication and alternatives to potential problems.

Earth-abundant magnetite with carbon coatings as reversible cathodes for stretchable zinc-ion batteries

Earth-abundant magnetite(Fe_(3)O_(4))as cathode materials in aqueous zinc-ion batteries(ZIBs)is limited by its very low capacity and poor cycling.Here,a combined strategy based on carbon coating and electrolyte optimization is adopted to improve the performance of Fe_(3)O_(4).The Zn-Fe_(3)O_(4)@C batteries display specific capacities of 93 mAh g^(−1) and 81%capacity retention after 200 cycles.Such performance is attributed to the enhanced electrical conductivity and structural stability of Fe_(3)O_(4)@C nanocomposites with suppressed iron dissolution.Experimental analysis reveals that the charge storage is contributed by diffusion-limited redox reactions and surface-controlled pseudocapacitance.A stretchable Zn-Fe_(3)O_(4)@C battery is further fabricated,showing stable performance when it is bent or stretched.Fe_(3)O_(4) is a promising cathode material for cost-effective,safe,sustainable and wearable energy supplies.

Ni–B-doped NaAlH_4 hydrogen storage materials prepared by a facile two-step synthesis method

By directly introducing Ni–B into NaAlH4 system using a facile two-step synthesis method, the effects of Ni–B on NaAlH4 were systematically investigated. NaAlH4 can be completely formed after 30 h milling under 1 MPa hydrogen pressure. In addition, the dehydrogenation kinetics of as-prepared NaAlH4 after different milling times were investigated. As the dehydrogenation temperature rises,both the hydrogen desorption capacity and dehydrogenation rate quickly increase. The apparent activation energy E a for Ni–B-doped NaAlH4 is calculated to be 61.91 k J mol-1 for the first dehydrogenation step. More importantly, the dehydrogenation temperature of as-prepared NaAlH4 nanocrystalline can be reduced to about 100 °C.

Enhancing the singlet oxygen capture and release rate of metal-organic frameworks through interpenetration tuning

Recognized as one of the important active species involved in varicus ractions,singlet oxygen(^(1)O_(2))shows potential applications in chemical.blological,and environmental related fields.However,the con-trolled capture and release of^(1)O_(2)are still facing huge challenges due to its short lifetime and high re-activity.Herein,a framework-interpenetration tuning strategy was applied on a metal-organic framework(MOF)that aiming to improve the capture and release rate of O.The porosity of the MOF was remark-ably enhanced with the structural evolution from seven-fold(termed NKM-181)to six-fold interpene-tration(termed NKM-182),and the active anthracene sites became much mare accessible.Such drastic process can be achieved as simple as exchanging the primitive MOF in selected solvent and occurred surprisingly as single-crystal to single-crystal transformation.Also,additionally owing to the unblocked regular channels,NKM-182 shown significantly improved^(1)O_(2)trapping and releasing rates compared to strates an unprecedented regulation of^(1)O_(2)capture and release that of in NKM-181.This work demon process,along with achieving the highest^(1)O_(2)capture and release rate among reported porous materi-als.furthermore.the obtalned endoperoxides with^(1)O_(2)loaded(termed EPO-NKM-181 and EPO-NKM-182)can be used as a high efficiency smart material for anti-fake application.

Electrostatically connected nanoarchitected electrocatalytic films for boosted water splitting

Active sites of two-dimensional(2D)electrocatalysts are often partially blocked owing to their inevitable stacking and hydrophobic polymeric binders in macroscale electrodes,therefore impeding their applications in efficient electrolyzers.Here,using layered double hydroxide(LDH)nanosheets as a model 2D electrocatalyst,we demonstrate that their performance toward water splitting can be boosted when they are electrostatically assembled into an organized structure pillared by hydrophilic polyelectrolytes or nanoparticles in a layer-by-layer(LbL)fashion.In particular,their mass activity on a planar electrode can be as large as 2.267 mA·μg^(-1) toward oxygen evolution reaction(OER),when NiFe-LDH nanosheets are electrostatically connected by poly(sodium 4-styrenesulfonate)(PSS),while drop-casted NiFe-LDH nanosheets only have a mass activity of 0.116 mA·μg^(-1).In addition,these homogeneous NiFe-LDH nanofilms can be easily deposited on three-dimensional(3D)surfaces with high areas,such as carbon cloths,to serve as practical electrodes with overpotentials of 328 mV at a current density of 100 mA·cm^(-2),and stability for 40 h.Furthermore,Pt nanoparticles can be LbL assembled with NiFe-LDH as bifunctional electrodes for synergistically boosted oxygen and hydrogen evolution reactions(HER),leading to successful overall water splitting powered by a 1.5 V battery.This study heralds the spatial control of 2D nanomaterials in nanoscale precision as an efficient strategy for the design of advanced electrocatalysts.

Rational design of ZnCdS/TpPa-1-COF heterostructure photocatalyst by strengthening the interface connection in solar hydrogen production reactions

ZnCdS quantum dots(QDs)are highly coveted in photocatalysis research for their exceptional visible-light responses and high light-absorption coefficients.However,their practical application is hindered by their tendency to aggregate,due to having high surface energies.To address this issue,herein,a heterostructure is synthesized by growing ZnCdS QDs with a size of approximately 5 nm onto the surface of a two-dimensional(2D)covalent organic framework(COF),TpPa-1-COF.This approach suppresses the aggregation of the QDs and improves their stability.The ZnCdS/TpPa-1-COF composite exhibited a peak hydrogen evolution rate of 6244.16μmol·g^(-1)·h^(-1),which was 2.89 and 4.18 times greater than that of ZnCdS and TpPa-1-COF,respectively.The zero-dimensional/two-dimensional(0D/2D)heterojunction formed by ZnCdS and TpPa-1-COF generates a strong interfacial force,which is attributed to the intimate contact between the interfaces.Tight connections accelerate charge separation,improve the utilisation of reduced electrons,and reduce the extent of agglomeration of the ZnCdS QDs,thereby resulting in high hydrogen production activity of the composites.Meanwhile,the photocatalytic mechanism is studied using Kelvin probe force microscopy and theoretical calculations.This study offers a novel approach for creating sulfide photocatalysts and is crucial for investigating the potential practical applications of the related photocatalysts.

Synergistically Directed Assembly of Aromatic Stacks Based Metal-Organic Frameworks by Donor-Acceptor and Coordination Interactions

A synergistically directed assembly approach to distinctive metal-organic frameworks utilizing both donor-acceptor (D-A) interaction from aromatic systems and coordination interactions is presented.Based on such an approach,the coronene-tpt (tpt =2,4,6-tri(4-pyridyl)-1,3,5-triazine) stacks based coronene-MOF-1-4 have been successfully fabricated.Their structural discrepancies with coroneneabsent control products,1'-4',illustrate clearly the significance of coronene-tpt based D-A interactions in these architectures.All these coronene-MOFs contain varied coronene-tpt stacks as organic secondary building blocks (SBUs),which are closely interrelated with the coordination based framework structures.Moreover,porous coronene-MOF-1 and-2 exhibit high physicochemical stability and significant light hydrocarbons storage and separation performances.

A new luminescent metal-organic framework for selective sensing of nitroaromatic explosives

A microporous luminescent metal-organic framework [Zn_4L_2(H_2O)_2].(H_2O)_m(DMA)_n(1)(H_4L=5,5'-((1H-pyrazole-3,5-dicarbonyl)bis(azanediyl))diisophthalic acid, DMA=N,N-dimethylacetamide) was synthesized and characterized by infrared radiation(IR), thermogravimetric analyses(TGA), powder X-ray diffraction spectra(PXRD) and X-ray diffraction. Complex 1has a three dimensional(3D) framework, which can be simplified as 5,5,5,5-c net with the Schlfi symbol of {43.64.83}{44.65.8}{45.65}2. This luminescent metal-organic framework(MOF) shows selectively sensitive to nitrobenzene and series of nitroaromatic explosives such as 4-nitrotoluene, 1,4-dinitrobenzene, 1,3-dinitrobenzene and 2,4-dinitrotoluene, and exhibits well recyclability. So complex 1 could be used to detect nitroaromatic explosives as a selective sensing material.

A cationic metal-organic framework based on {Zn4} cluster for rapid and selective adsorption of dyes

Until now, to remove the harmful organic dyes from effluents is an outstanding challenge. The design and synthesis of new porous materials capable of selectively adsorbing dyes are critical to the environment and human health. Here, a unique cluster-based cationic metal-organic framework, named{[Zn8（BTA）6（L）5Cl2]·（NO3）3}·5 DMF（NUM-4） was synthesized, which displays one-dimensional（1 D）open channels along a axis in its 3 D supramolecular stacking structure. Benefiting from the nature of cationic framework and high surface area/pore volume, NUM-4 shows rapid and selective adsorption of anionic dyes（MO, AO, CR and MB） based on the charge-exclusive effect. Besides, the adsorbed dyes can be easily released in NH4Cl saturated solution of ethanol.

Dual-functional ion redistributor for dendrite-free lithium metal anodes

With the rapid development of high-end electronic devices such as electric vehicles and portable electronics products,the currently widely used lithium(Li)-ion batteries are found greatly difficult to meet the growing demand for energy storage[1,2].

[Co(NH_3)_6]_2[Cd_8(C_2O_4)_(11)(H_2O)_4]·8H_2O: A 5-connected sqp topological metal-organic framework co-templated by Co(NH_3)_6^(3+) cation and (H_2O)_4 cluster

In our efforts to construct new metal-organic frameworks （MOFs） by template-directing method, a new cadmium oxalate, [Co（NH3）612[Cds（C204）ll（H20）4].8H20 （denoted HNU-1 ）, has been synthesized under hydrothermal condition in the presence of C0（NH3）6C13, The crystal structure of HNU-1 was determined by single-crystal X-ray diffraction （monoclinic, C2/c）, a = 11.126（2）A, b = 17.361 （4）,A, c = 16.119（3）A, fi = 102.40（3）, V = 3040.8（10） A and Z = 8. The open framework of HNU-1 contains 12-ring channels and exhibits a 5-connected sqp topological network with dinuclear Cd（ll） clusters acting as nodes. The Co（NH3）63＋ cations and unusual hydrogen-bonded （H20）4 clusters are found in the 12-ring channels with an alternative arrangement. It is believed that the （H20）4 clusters play a co-templating role in the crystallization of HNU-1.

Crystalline-State Solvent:Metal-Organic Frameworks as a Platform for Intercepting Aggregation-Caused Quenching

The sequestration of organic luminescent molecules(OLMs)within cage-based metal-organic frameworks(MOFs)as a dispersion platform has been developed to impede aggregation-caused quenching(ACQ).The homogenous encapsulation of distinct luminescent guests of different sizes and emissive behaviors in the cage structure of a MOF resulted in high fluorescent quantum yields of 44.8%for DAPI@NKU-110(DAPI=4',6-diamidino-2-phenylindole),65.4%for TPPA@NKU-110(TPPA=tris(4-(pyridin-4-yl)phenyl)amine),31.3%for R6G@NKU-110(R6G=Rhodamine 6G),and 58.3%for PY@NKU-110(PY=Pyronin Y),attributable to the confinement effect caused by the rigid cages of NKU-110.More significantly,a positive correlation of the encapsulated quantity of OLMs with their concentration in the in-situ solvothermal reaction was unveiled by spectral analysis and utilized to facilely fabricate a white-light-emitting crystal material TPPA+R6G@NKU-110.This material features a large crystal size on the millimeter-scale,broadband white emission,ideal CIE coordinates(0.33,0.34),and a high quantum yield(49.1%)when excited at 365 nm.Moreover,such a strategy can be easily generalized to an abundance of other cage-based MOFs and a plentiful volume of OLMs for the future development of colorful,high performance luminescent materials.

In-situ cation exchange enhances room temperature phosphorescence of a family of metal-organic frameworks

The rational designability and chemical tunability of metal-organic frameworks(MOFs)are enabling tributes to efficaciously enhance their room temperature phosphorescence(RTP)performance.A family of stable anionic MOFs,[Zn_(2)(4,5-ImDC)_(2)]M_(2)(NKU-132,M=(CH_(3))_(2)NH_(2)or(CH_(2)CH_(3))_(2)NH_(2)),featuring significant RTP have been synthesized.By rational cation selection and in-situ replacement from dimethylammonium to diethylammonium,the phosphorescence lifetime is increased from 30.88 to126.3 ms,along with less sensitivity to air.This work provides an anti-quenching and lifetime tuning example for RTP-MOFmaterials via facile host-guest chemistry.

Rupture stress of liquid metal nanoparticles and their applications in stretchable conductors and dielectrics

Few works had systematically investigated the relationship between the rupture stress of the oxide shell and the diameter of liquid metal nanoparticles(LMNPs).Here,we fabricated a series of elastomer/LMNPs composites,which were based on various polyurethanes with different shore hardness and LMNPs with different diameters,to systematically study the rupture stress of LMNPs.We established a reliable and guidable relationship between the stress–strain curves of elastomers with different shore hardness and rupture stress of LMNPs with various diameters by both experiments and numerical calculations.Based on this guidance,we can facilely prepare stretchable conductors with remarkable stretchability and conductivity(i.e.,24,130 S·cm^(−1)at 500%strain)and stretchable dielectrics with excellent stretchability and permittivity(i.e.,dielectric constant of 76.8 with 580%strain)through controlling the shore hardness of elastomers and diameter of LMNPs.This work will facilitate the systematic study of LMNPs and expand their use in stretchable electronics.

Highly selective and turn-on fluorescence probe with red shift emission for naked-eye detecting Al^(3+)and Ga^(3+)based on metal-organic framework

A novel ZnII-based metal-organic framework with the formula of{[Zn_(2)(BBIP)_(2)(NDC)_(2)]·H_(2)O}n(JXUST-5)derived from 3,5-bis(benzimidazol-1-yl)pyridine(BBIP)and 1,4-naphthalenedicarboxylic acid(H_(2)NDC)has been synthesized.The adjacent Zn^(II)ions are linked through two BBIP ligands to form a[Zn_(2)(BBIP)_(2)]secondary building unit(SBU).The neighbouring SBUs are further connected by NDC^(2-)withμ2-η^(1):η^(1)andμ2-η^(1):η^(1):η^(1)bridging modes to form a two-dimensional(2D)framework.Topological analysis shows that JXUST-5 could be simplified as an uninodal fes topology with a point symbol of{4.8^(2)}.Furthermore,the 2D framework net could be extended through C-H···πinteraction to form the three-dimensional supramolecular structure.Luminescent experiments suggest that JXUST-5 could selectively and sensitively recognize Al^(3+)and Ga^(3+)through fluorescence enhancement effect along with a relatively large red shift.The detection limits for Al^(3+)and Ga^(3+)are 0.17 and 0.69 ppm,respectively.Interestingly,the sensing process for both Al^(3+)and Ga^(3+)could be directly observed with naked eyes under 365 nm UV lamp.Notably,JXUST-5 could be recycled at least five times as a fluorescent sensor toward Al^(3+)and Ga^(3+),which is the second example of turn-on MOF based fluorescent sensor toward Ga^(3+).

双配体基二维导电金属-有机框架的一步合成及其储锂性能研究

基于双氧化还原活性有机配体的二维导电金属-有机框架(2D c-MOFs)是极具潜力的锂离子电池(LIBs)电极材料.然而,双配体竞争配位导致该类材料合成具有极大挑战性.本文以乙二胺为调节剂,发展了一步法合成双配体基2D c-MOF Cu_(3)(HHTP)(THQ)(HHTP=2,3,6,7,10,11-六羟基三亚苯,THQ=四羟基-1,4-苯醌).所得Cu_(3)(HHTP)(THQ)具有良好的导电性、丰富的活性位点和优异的化学稳定性,其作为LIBs负极材料展现出高比容量、良好的倍率性能和长循环稳定性.实验结果和理论计算表明,Cu_(3)(HHTP)(THQ)中CuO_(4)活性位点和苯环单元均参与了锂存储,从而优化了储锂性能.该工作为构筑双配体基2D c-MOFs和高性能LIBs电极材料提供了新的途径.

基于荧光金属有机框架的化学检测器研究进展（英文）

由金属离子/簇与有机配体构筑的金属有机框架(metal-organic frameworks, MOFs)近年来受到广泛关注.作为一类典型的MOFs材料,荧光MOFs(LMOFs)因具有结晶度高、结构多样、孔隙率可调、孔道易修饰等特点在化学检测领域展现出重要的应用前景.迄今为止,大量的LMOFs已被合成并用于多种物质检测.本文综述了LMOFs对金属阳离子、阴离子、小分子、有机物、爆炸物、气体、生物分子等物质检测的近期研究进展,总结了荧光检测机理和结构-性能关系,为后续定向构筑性能优异的新型LMOFs材料提供参考.

Synthesis,structure and magnetic properties of manganese(Ⅱ)coordination polymer with azido and zwitterionic dicarboxylate ligand

A coordination polymer formulated as {[Mn2L（N3）4]·2H2O）n（1） [L = 1,4-bis（pyridinil-3-carboxylato）-1,4- dimethylbenzene] was synthesized and structurally and magnetically characterized. The uniform Mn（Ⅱ） chains with mixed （μ-EO-N3）2（μ-COO） triple bridges （EO = end-on） are linked by L ligands to generate a 2-fold interpenetrating 3D framework. Meanwhile, magnetism analysis reveals antiferromagnetic coupling for 1.

High-mobility patternable MoS_(2) percolating nanofilms

Fabrication of large-area and uniform semiconducting thin films of two-dimensional(2D)materials is paramount for the full exploitation of their atomic thicknesses and smooth surfaces in integrated circuits.In addition to elaborate vapor-based synthesis techniques for the wafer-scale growth of 2D films,solution-based approaches for high-quality thin films from the liquid dispersions of 2D flakes,despite underdeveloped,are alternative cost-effective tactics.Here,we present layer-by-layer(LbL)assembly as an effective approach to obtaining scalable semiconducting films of molybdenum disulfide(MoS_(2))for field-effect transistors(FETs).LbL assembly is achieved by coordinating electrochemically exfoliated MoS_(2) with cationic poly(diallyldimethylammonium chloride)(PDDA)through electrostatic interactions.The PDDA/MoS_(2) percolating nanofilms show controlled and self-limited growth on a variety of substrates,and are easily patterned through lift-off processes.Ion gel gated FETs are fabricated on these MoS_(2) nanofilms,and they show mobilities of 9.8 cm^(2)·V^(−1)·s^(−1),on/off ratios of 2.1×10^(5) with operating voltages less than 2 V.The annealing temperature in the fabrication process can be as low as 200℃,thereby permitting the fabrication of flexible FETs on polyethylene terephthalate substrates.The LbL assembly technique holds great promise for the large-scale fabrication of flexible electronics based on solution-processed 2D semiconductors.

Sulfonated Hollow Covalent Organic Polymer： Highly-Selective Adsorption toward Cationic Organic Dyes over Anionic Ones in Aqueous Solution

A sulfonated hollow covalent organic polymer （sh-COP-P） was prepared by post sulfonation of hollow covalent organic polymer （h-COP-P） synthesized through poly-condensation of tetrabiphenylporphyrin （TBPP）. In comparison with h-COP-P, sh-COP-P exhibits significantly enhanced adsorp- tion capacity of organic cationic dyes in aqueous solutions accompanied with notably reduced adsorption capacity of anionic dyes. This gives sh-COP-P a satisfactory performance in selectively separating cationic organic dyes from anionic ones, mainly attributed to the electrostatic interaction between polymer backbone and the guest molecules.