A Rapid-Ab/Desorption and Portable Photothermal MIL- 101(Cr) Nanofibrous Composite Membrane Fabricated by Spray-Electrospinning for Atmosphere Water Harvesting

MIL-101(Cr)is a promising moisture absorbent for solar-driven water harvesting from moisture to tackle the worldwide water shortage issue.However,the MIL-101(Cr)powder suffers from a long ab/desorption cycle due to the crystal aggregation caused by its inherent powder properties.Here,we demonstrate a MIL-101(Cr)nanofibrous composite membrane with a nanofibrous matrix where MIL-101(Cr)is monodisperse in the 3D porous nanofibrous matrix through a simple spray-electrospinning strategy.The continuous porous nanofibrous matrix not only offers sufficient sites for MIL-101(Cr)loading but also provides rapid moisture transport channels,resulting in a super-rapid ab/desorption duration of 50 min(including an absorption process for 40 min and a desorption process for 10 min)and multicycle daily water production of 15.9 L kg^(−1) d^(−1).Besides,the MIL-101(Cr)nanofibrous composite membrane establishes a high solar absorption of 92.8%,and excellent photothermal conversion with the surface temperature of 70.7°C under one-sun irradiation.In addition,the MIL-101(Cr)nanofibrous composite membrane shows excellent potential for practical application due to its flexibility,portability,and use stability.This work provides a new perspective of shortening MOF ab/desorption duration by introducing a porous nanofibrous matrix to improve the specific water production for the solar-driven ab/desorption water harvesting technique.

A series of formic acid MOFs/polylactic acid blending composites with the improved dielectric performance in Co(Ⅱ)systems

In order to improve the limited compatibility of existing polymer/ceramic dielectric composites and further enhance the energy storage density,MOF/polymer composite dielectrics have been explored,which exhibit good compatibility to the polymer matrix from abundant organic groups of the inorganic–organic hybrid metal-organic framework(MOF)fillers.However,they still lack a clear composition–structure–property rule,and the precise design of MOF fillers and polymer matrix becomes a prominent problem in these composites due to the diversity of the metal ions and the organic groups.Thus,in this paper,we present a series of formic acid MOFs/polylactic acid dielectric composites in which ferroelectric formic acid MOFs,namely PDLLA/[NH_(3)(CH_(2))_(4)NH_(3)][M^(Ⅱ)(HCOO)_(3)]_(2)and PDLLA/[CH_(3)NH_(3)][M^(Ⅱ)(HCOO)_(3)]_(2),in which the formic acid MOFs are with different structures and different metal ions as fillers,including[NH_(3)(CH_(2)T_(4)NH_(3))][M^(Ⅱ)(HCOO)_(3)]_(2)(namely MOF–Co(M=Co),MOF–Mg(M=Mg),MOF–Mn(M=Mn),with 1,4-butanediamine ion as guest)and[CH_(3)NH_(3)][M^(Ⅱ)(HCOO)_(3)]_(2)(namely MOF–Co_(2)(M=Co),MOF–Ni_(2)(Ni),with methylamine ion as guest).The composition and morphology of composite films were characterized by XRD,IR,SEM,DSC and UV,respectively,while the dielectric characterizations of the composites including the dielectric permittivity,the dielectric loss,the breakdown field strength and the energy density were also performed.The composition–structure–property relationships were also investigated including the influence of MOF content and MOF category.With the introduction of MOFs,the dielectric constant of the polylactic acid substrate was improved slightly while the breakdown field strength can be improved in some systems.Interestingly,the Co(Ⅱ)-containing formic acid MOF has advantages over other formic acid MOFs with similar structure for the enhancement of the dielectric constant and breakdown field strength.Also,in some composite films with methylamine ion guest MOF fillers and low-MOF content(MOF–Co_(2)(1 vol.%)and MOF–Ni_(2)(1 vol.%)),the breakdown electric field enhanced significantly and further led to improved energy storage density which was about 43%higher than that of the polylactic acid matrix.The possible reason is that in these composites,the orientation of C–H bonds of MOFs seems more beneficial to the formation of hydrogen bonds between the carboxyl group of formic acid and the polylactic acid matrix.These relationships obtained from formic acid MOFs/polylactic acid composites are valuable to the design of high-performance polymer/MOF energy storage composites and may be a new perspective to the practical use of ferroelectric MOFs.

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.

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.

Two-dimensional CuO nanosheets-induced MOF composites and derivatives for dendrite-free zinc-ion batteries

Uncontrollable dendrite growth and side reactions resulting in short operating life and low Coulombic efficiency have severely hindered the further development of aqueous zinc-ion batteries(AZIBs).In this work,we designed to grow zeolitic imidazolate framework-8(ZIF-8)uniformly on CuO nanosheets(NSs)and prepared carbon-coated CuZn alloy NSs(CuZn@C NSs)by calcination under H_(2)/Ar atmosphere.As reflected by extended X-ray absorption fine structure(EXAFS),density functional theory(DFT),in-situ Raman,the Cu–Zn and Zn–N bonds present in CuZn@C NSs act as zincophilic sites to uniformly absorb Zn ions and inhibit the formation of Zn dendrites.At the same time,CuZn@C NSs hinder the direct contact between zinc anode and electrolyte,preventing the occurrence of side reactions.More impressively,the symmetric cells constructed with CuZn@C NSs anodes exhibited excellent zinc plating/exfoliation performance and long life cycle at different current densities with low voltage hysteresis.In addition,low polarization,high capacity retention,long cycle life over 1000 cycles at 5 A∙g^(−1) were achieved when CuZn@C NSs were used as anodes for CuZn@C/V_(2)O_(5)full cells.

Two-dimensional MOF Cu-BDC nanosheets/ILs@silica core-shell composites as mixed-mode stationary phase for high performance liquid chromatography

Here,silica microspheres were decorated with two-dimensional metal-organic frameworks(2 D MOFs)nanosheets and ionic liquids,and evaluated as the mixed-mode stationary phase for chromatographic separation.The ionic liquids were used to assist the synthesis of 2 D MOFs nanosheets,and also acted as adhesives among the nanosheets and silica.In contrast with the 2 D MOFs-based column without ionic liquids and commercial columns,the prepared column exhibited enhanced chromatographic separation performance for partially hydrophilic compounds such as alkaloids,sulfonamides and antibiotics,etc.In addition to excellent chromatographic repeatability and stability,it has also been verified that the composites could be easily and repeatedly prepared.The relative standard deviation of the retention time of the same type of analyte between the three batches of materials was ranging from 0.21%to 1.7%.In short,these results indicated that the synthesized composites were promising separation material for liquid chromatography,which made it possible to broaden the application of 2 D MOFs in the field of chromatography.

Sandwich-like QDs/MOFs films for selective sensing and multicolor emitting

A novel type sandwich-like composite films composed of ZIF-8 and CdTe QDs were successfully constructed through facile layer-by-layer assembly strategy and their potential applications were also explored.Based on the limitation effects of the aperture of ZIF-8,CdTe QDs/ZIF-8 fluorescent composite films exhibit obvious selective optical response toward hydrogen peroxide and folic acid.Furthermore,tunable colorful light emission composite films in the red-green region are obtained through incorporating two different sized QDs and ZIF-8 films into one composite films.

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.