Application of metal organic framework in wastewater treatment

Water pollution is an increasingly serious environmental problem because many pollutants have carcinogenic effects on humans and aquatic organisms.Metal organic framework(MOF),made up of metal ions and multifunctional organic ligands,has been one of the most concerned materials because of its adjustable and regular pore structure.MOFs have always shown attractive advantages in membrane separation and adsorption technologies,among which water-stable MOFs are particularly prominent in wastewater treatment(WWT)applications.This review systematically summarizes the application of MOF membranes in membrane filtration,membrane pervaporation and membrane distillation.Also,the adsorption mechanisms of heavy metals,dyes and antibacterials in wastewater have been concluded.In order to tap the full application potential of pristine MOFs in sustainable wastewater treatment,current challenges are discussed in detail and future research directions are proposed.

3D printing of personalized polylactic acid scaffold laden with GelMA/autologous auricle cartilage to promote ear reconstruction

At present,the clinical reconstruction of the auricle usually adopts the strategy of taking autologous costal cartilage.This method has great trauma to patients,poor plasticity and inaccurate shaping.Three-dimensional(3D)printing technology has made a great breakthrough in the clinical application of orthopedic implants.This study explored the combination of 3D printing and tissue engineering to precisely reconstruct the auricle.First,a polylactic acid(PLA)polymer scaffold with a precisely customized patient appearance was fabricated,and then auricle cartilage fragments were loaded into the 3D-printed porous PLA scaffold to promote auricle reconstruction.In vitro,gelatin methacrylamide(GelMA)hydrogels loaded with different sizes of rabbit ear cartilage fragments were studied to assess the regenerative activity of various autologous cartilage fragments.In vivo,rat ear cartilage fragments were placed in an accurately designed porous PLA polymer ear scaffold to promote auricle reconstruction.The results indicated that the chondrocytes in the cartilage fragments could maintain the morphological phenotype in vitro.After three months of implantation observation,it was conducive to promoting the subsequent regeneration of cartilage in vivo.The autologous cartilage fragments combined with 3D printing technology show promising potential in auricle reconstruction.

PtZn nanoparticles supported on porous nitrogen-doped carbon nanofibers as highly stable electrocatalysts for oxygen reduction reaction

The oxygen reduction reaction(ORR)electrocatalytic activity of Pt-based catalysts can be significantly improved by supporting Pt and its alloy nanoparticles(NPs)on a porous carbon support with large surface area.However,such catalysts are often obtained by constructing porous carbon support followed by depositing Pt and its alloy NPs inside the pores,in which the migration and agglomeration of Pt NPs are inevitable under harsh operating conditions owing to the relatively weak interaction between NPs and carbon support.Here we develop a facile electrospinning strategy to in-situ prepare small-sized PtZn NPs supported on porous nitrogen-doped carbon nanofibers.Electrochemical results demonstrate that the as-prepared PtZn alloy catalyst exhibits excellent initial ORR activity with a half-wave potential(E_(1/2))of 0.911 V versus reversible hydrogen electrode(vs.RHE)and enhanced durability with only decreasing 11 mV after 30,000 potential cycles,compared to a more significant drop of 24 mV in E_(1/2)of Pt/C catalysts(after 10,000 potential cycling).Such a desirable performance is ascribed to the created triple-phase reaction boundary assisted by the evaporation of Zn and strengthened interaction between nanoparticles and the carbon support,inhibiting the migration and aggregation of NPs during the ORR.

3D printing of calcium phosphate bioceramic with tailored biodegradation rate for skull bone tissue reconstruction

The bone regenerative scaffold with the tailored degradation rate matching with the growth rate of the new bone is essential for adolescent bone repair.To satisfy these requirement,we proposed bone tissue scaffolds with controlled degradation rate using osteoinductive materials(Ca-P bioceramics),which is expected to present a controllable biodegradation rate for patients who need bone regeneration.Physicochemical properties,porosity,compressive strength and degradation properties of the scaffolds were studied.3D printed Ca-P scaffold(3DS),gas foaming Ca-P scaffold(FS)and autogenous bone(AB)were used in vivo for personalized beagle skull defect repair.Histological results indicated that the 3DS was highly vascularized and well combined with surrounding tissues.FS showed obvious newly formed bone tissues.AB showed the best repair effect,but it was found that AB scaffolds were partially absorbed and degraded.This study indicated that the 3D printed Ca-P bioceramics with tailored biodegradation rate is a promising candidate for personalized skull bone tissue reconstruction.

Hierarchical porous nitrogen,oxygen,and phosphorus ternary doped hollow biomass carbon spheres for high-speed and long-life potassium storage

Limited lithium resources have promoted the exploration of new battery technologies.Among them,potassium-ion batteries are considered as promising alternatives.At present,commercial graphite and other carbon-based materials have shown good prospects as anodes for potassium-ion batteries.However,the volume expansion and structural collapse caused by periodic K+insertion/extraction have severely restricted further development and application of potassium-ion batteries.A hollow biomass carbon ball(NOP-PB)ternarily doped with N,O,and P was synthesized and used as the negative electrode of a potassium-ion battery.X-ray photoelectron spectroscopy,Fourier‐transform infrared spectroscopy,and transmission electron microscopy confirmed that the hollow biomass carbon spheres were successfully doped with N,O,and P.Further analysis proved that N,O,and P ternary doping expands the interlayer distance of the graphite surface and introduces more defect sites.DFT calculations simultaneously proved that the K adsorption energy of the doped structure is greatly improved.The solid hollow hierarchical porous structure buffers the volume expansion of the potassium insertion process,maintains the original structure after a long cycle and promotes the transfer of potassium ions and electrons.Therefore,the NOP‐PB negative electrode shows extremely enhanced electrochemical performance,including high specific capacity,excellent long‐term stability,and good rate stability.

Metal-organic framework-derived phosphide nanomaterials for electrochemical applications

Because of features,such as adjustable structures,high porosity,and high crystallinity,metal-organic frameworks(MOFs)deservedly have received considerable attention.Nevertheless,there is still room for improvements in the electrical conductivity and chemical stability of some MOFs,because of which they cannot be utilized as electrode materials.Fortunately,MOF derivatives have received widespread attention in recent years,especially phosphide materials,which are widely used in practical applications because of their outstanding conductivity,excellent specific surface area,and standout charge mobility.In this review,the latest developments of MOF-derived phosphides in electrocatalysis related to energy,including the excellent performance in terms of electrochemical energy storage and ingenious strategies,and diversified synthetic approaches are emphasized and summarized.Additionally,the arduous task and feasible proposals of MOF-derived phosphides are also discussed.

Fabrication, characterization and electrochemical properties of porous palladium bulk samples with high porosity and hierarchical pore structure

In the present study,porous bulk palladium samples were prepared by sodium chloride salt powder spacer incorporation and removal combined with dealloying.The obtained porous Pd bulks were characterized by X‐ray diffraction,field‐emission scanning electron microscopy and N2adsorption isotherm measurements.The prepared porous Pd bulk samples showed a hierarchical pore structure,a high porosity of^88%,a high surface area of^54m2/g,and a compression strength of^0.5MPa.Electrochemical measurements were performed to evaluate the electrocatalytic properties of the porous Pd bulk samples,revealing their effectiveness for ethanol oxidation.

Chondroitinase ABC treatment of injured spinal cord in rats Evaluation of long-term outcomes

Chondroitin sulfate proteoglycans （CSPGs） which are produced by mature oligodendrocytes and reactive astrocytes can be upregulated after spinal cord injury and contribute to regenerative failure. Chondroitinase ABC （ChABC） digests glycosaminoglycan chains on CSPGs and can thereby overcome CSPG-mediated inhibition. However, many current studies have used an incomplete spinal cord injury model, and examined results after 8-12 weeks of ChABC treatment. In this study, a complete rat spinal cord transection injury model was used to study the long-term effects of ChABC treatment by subarachnoid catheter. Pathology of spinal cord regeneration was compared with control 24 weeks following ChABC treatment using immunohistochemistry and axon tracing techniques. At 24 weeks after injury, neurofilament 200 expression was significantly greater in the ChABC treatment group compared with the transection group. In the ChABC treatment group, axonal growth was demonstrated by a large number of biotinylated dextran amine positive axons caudal to, or past, the epicenter of injury. Biotinylated dextran amine-labeled fibers were found in the proximal end of the spinal cord in the transection alone group. These results confirm that ChABC can promote axon growth, neural regeneration, and repair after spinal cord injury in rats long after the initial injury.

Damage mechanisms and recent research advances in Ni-rich layered cathode materials for lithium-ion batteries

Nickel-rich cathode is considered to be the cathode material that can solve the short-range problem of electric vehicles with excellent elec-trochemical properties and low price.However,microcracks,lithium–nickel hybridization,and irreversible phase transitions during cycling limit their commercial applications.These issues should be resolved by modifications.In recent years,it has been favored by researchers to solve a large number of problems by combining multiple modification strate-gies.Therefore,this paper reviews recent developments in various modification techniques for nickel-rich cathode materials that have improved their electrochemical characteristics.The summary of multiple modifications of nickel-rich materials will play a guiding role in future development.

Talcum-doped composite separator with superior wettability and heatproof properties for high-rate lithium metal batteries

Separator is supposed to own outstanding thermal stability,superior wettability and electrolyte uptake,which is essential for developing high-rate and safe lithium metal batteries(LMBs).However,commercial polyolefin separators possess poor wettability and limited electrolyte uptake.For addressing this issue,we put forward a composite separator to implement above functions by doping layered-silicate(talcum)into polyvinylidene fluoride(PVDF).With significant improvement of electrolyte absorption benefiting from the strong adsorption energy values(-1.64-1.70 eV)between talcum and the electrolyte in lithium metal batteries,PVDF/Talcum(PVDF/TM)composite separator owns a small contact angle and superior electrolyte uptake.PVDF/TM composite separator with 10 wt%talcum(T-10)owns a tiny contact angle of 8°,while those of polypropylene(PP)and PVDF are 48°and 20°with commercial electrolyte.Moreover,the addition of thermotolerant talcum endows the T-10 composite separator with great thermostability,whose thermal shrinkage is only 5.39%at 150°C for 0.5 h.The cell with LiFeO4cathode and the T-10 composite separator reaches 91.7 m Ah/g in discharge capacity at 4.8 m A/cm^(2)(10 C),far superior to that with pure PVDF separator(56.3 m Ah/g)and PP(51.4 m Ah/g).

Ambient ammonia production via electrocatalytic nitrite reduction catalyzed by a CoP nanoarray

Industrial-scale ammonia(NH_(3))production mainly relies on the energy-intensive and environmentally unfriendly Haber-Bosch process.Such issue can be avoided by electrocatalytic N_(2) reduction which however suffers from limited current efficiency and NH3 yield.Herein,we demonstrate ambient NH_(3) production via electrochemical nitrite(NO_(2)^(-))reduction catalyzed by a CoP nanoarray on titanium mesh(CoP NA/TM).When tested in 0.1 M PBS(pH=7)containing 500 ppm N0_(2)^(-),such CoP NA/TM is capable of affording a large NH_(3) yield of 2,260.7±51.5μg·h^(-1)·cm^(-2) and a high Faradaic efficiency of 90.0±2.3%at-0.2 V vs.a reversible hydrogen electrode.Density functional theory calculations reveal that the potential-determining step for NO_(2)^(-)reduction over CoP(112)is*NO2→*NO_(2)H.

In situ grown Fe_(3)O_(4)particle on stainless steel:A highly efficient electrocatalyst for nitrate reduction to ammonia

NH_(3)is an essential feedstock for fertilizer synthesis.Industry-scale NH_(3)synthesis mostly relies on the Haber-Bosch method,however,which suffers from massive CO_(2) emission and high energy consumption.Electrocatalytic NO_(3)-reduction is an attractive substitute to the Haber-Bosch method for synthesizing NH_(3)under mild conditions.As this reaction will produce a variety of products,it highly desires efficient and selective electrocatalyst for NH_(3)generation.Here,we report in situ grown Fe_(3)O_(4)particle on stainless steel(Fe_(3)O_(4)/SS)as a high-efficiency electrocatalyst for NO_(3)^(-)reduction to NH_(3).In 0.1 M NaOH with 0.1 M NaNO_(3),such Fe_(3)O_(4)/SS reaches a remarkable Faradaic efficiency of 91.5%and a high NH_(3)yield of 10,145μg·h^(-1)·cm^(-2)at-0.5 V vs.reversible hydrogen electrode(RHE).Furthermore,it owns robust structural and electrochemical stability.This work provides useful guidelines to expand the scope of metallic oxide electrocatalysts for NH_(3)synthesis.The catalytic mechanism is uncovered and discussed further by theoretical calculations.

Enhancing electrocatalytic N_(2)-to-NH_(3) fixation by suppressing hydrogen evolution with alkylthiols modified Fe_(3)P nanoarrays

Electrocatalytic N_(2) reduction provides an attractive alternative to Haber-Bosch process for artificial NH_(3) synthesis.The difficulty of suppressing competing proton reduction,however,largely impedes its practical use.Herein,we design a hydrophobic octadecanethiol-modified Fe_(3)P nanoarrays supported on carbon paper(C18@Fe_(3)P/CP)to effectively repel water,concentrate N_(2),and enhance N_(2)-to-NH_(3) conversion.Such catalyst achieves an NH_(3) yield of 1.80×10^(-10) mol s^(-1)·cm^(-2) and a high Faradaic efficiency of 11.22%in 0.1 M Na_(2)SO_(4),outperforming the non-modified Fe_(3)P/CP(2.16×10^(-11) mol s^(-1)·cm^(-2),0.9%)counterpart.Significantly,C18@Fe_(3)P/CP renders steady Nrfixing activlty/selectivity in cycling test and exhibits durability for at least 25 h.First-principles calculations suggest that the surface electronic structure and chemical activity of Fe_(3)P can be well tuned by the thiol modification,which facilitates N_(2) electroreduction activity and catalytic formation of NH_(3).

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.

Multiscale manipulating induced flexible heterogeneous V-NiFe_(2)O_(4)@Ni_(2)P electrocatalyst for efficient and durable oxygen evolution reaction

Water electrolysis is severely impeded by the kinetically sluggish oxygen evolution reaction(OER)due to its inherent multistep four-electron transfer mechanism.However,designing advanced OER electrocatalysts with abundant active sites,robust stability,and low cost remains a huge challenge.Herein,a facile and versatile multiscale manipulating strategy was proposed to construct a novel V-NiFe_(2)O_(4)@Ni_(2)P heterostructure self-supported on Ni foam(V-NiFe_(2)O_(4)@Ni_(2)P/NF).In such unique architecture,the intrinsic OER catalytic activity was greatly boosted by the in-situ generated heterogeneous Ni_(2)P phase induced by precisely selective phosphorylation of the NiFe-precursor,while the synchronous metal V doping stimulated the activity via modulating the electronic configuration,thus synergistically promoting its OER kinetics.In addition,the binder-free catalyst built from three-dimensional(3D)nanosheet arrays(NSs)can offer a large active surface for efficient charge/mass transfer and a robust scaffold for the integrated structure.The as-prepared flexible electrode exhibited superior OER activity with an ultra-low overpotential of 230 mV at 50 mA·cm^(−2)and outstanding long-term stability for 40 h.This discovery is expected to provide an opportunity to explore efficient and stable commercial materials for scalable,efficient,and robust electrochemical hydrogen(H_(2))production.

Enhanced N_(2)-to-NH_(3)conversion efficiency on Cu3P nanoribbon electrocatalyst

Ambient electroreduction of nitrogen(N_(2))is considered as a green and feasible approach for ammonia(NH_(3))synthesis,which urgently demands for efficient electrocatalyst.Morphology has close relationship with catalytic activity of heterogeneous catalysts.Nanoribbon is attractive nanostructure,which possesses the flexibility of one-dimensional nanomaterials,the large surface area of two-dimensional nanomaterials,and lateral size confinement effects.In this work,Cu_(3)P nanoribbon is proposed as a highly efficient electrocatalyst for N_(2)-to-NH_(3)conversion under benign conditions.When measured in N_(2)-saturated 0.1 M HCl,such Cu_(3)P nanoribbon achieves high performance with an excellent Faradaic efficiency as high as 37.8%and a large yield of 18.9μg·h^(−1)·mgcat.−1 at−0.2 V.It also demonstrates outstanding stability in long-term electrolysis test at least for 45 h.

A DFT study of Ti_(3)C_(2)O_(2)MXenes quantum dots supported on single layer graphene:Electronic structure an hydrogen evolution performance

Heterojunction structure has been extensively employed for the design of novel catalysts.In the present study,density functional theory was utilized to investigate the electronic structure and hydrogen evolution performance of Ti_(3)C_(2)O_(2)MXene quantum dots/graphene(QDs/G)heterostructure.Results show that a slight distortion can be observed in graphene after hybriding with QDs,due to which the electronic structure of QDs have been changed.Associated with such QDs-graphene interaction,the catalytic activity of Ti_(3)C_(2)O_(2)QDs has been optimized,leading to excellent HER catalytic performance.

CeO_(2) nanoparticles with oxygen vacancies decorated N-doped carbon nanorods:A highly efficient catalyst for nitrate electroreduction to ammonia

Electrocatalytic nitrate reduction reaction(NO_(3)−RR)emerges as a highly efficient approach toward ammonia synthesis and degrading NO_(3)−contaminant.In our study,CeO_(2) nanoparticles with oxygen vacancies(VO)decorated N-doped carbon nanorods on graphite paper(CeO_(2)−x@NC/GP)were demonstrated as a highly efficient NO_(3)−RR electrocatalyst.The CeO_(2)−x@NC/GP catalyst manifests a significant NH_(3 )yield up to 712.75μmol·h^(−1)·cm^(−2) at−0.8 V vs.reversible hydrogen electrode(RHE)and remarkable Faradaic efficiency of 92.93%at−0.5 V vs.RHE under alkaline conditions,with excellent durability.Additionally,an assembled Zn-NO_(3)−battery with CeO_(2)−x@NC/GP as cathode accomplishes a high-power density of 3.44 mW·cm^(−2) and a large NH3 yield of 145.08μmol·h^(−1)·cm^(−2).Density functional theory results further expose the NO_(3)−reduction mechanism on CeO_(2)(111)surface with VO.

An effective strategy for preparing transparent ceramics using nanorod powders based on pressure-assisted particle fracture and rearrangement

Achieving full densification of some ceramic materials,such as Y_(2)O_(3),without sintering aids by spark plasma sintering(SPS)is a great challenge when plastic deformation contributes limitedly to the densification as the yield stress of the material at an elevated temperature is higher than the applied sintering pressure.Herein,we demonstrate that particle fracture and rearrangement is an effective strategy to promote the densification during the pressure-assisted sintering process.Specifically,Y_(2)O_(3) nanocrystalline powders composed of nanorod and near-spherical particles were synthesized and sintered at various temperatures by the SPS.The results show that the relative density of the ceramics prepared by the nanorod powders is higher than the density of the ceramics from the near-spherical powders after 600℃ due to the fracture and rearrangement of the nanorods at low temperatures,which leads to the decrease of particle size and the increase of density and homogeneity.Based on this novel densification mechanism,ultrafine-grained Y_(2)O_(3) transparent ceramics with good optical and mechanical properties were fabricated successfully from the nanorod powders.

Bi nanoparticles/carbon nanosheet composite:A high-efficiency electrocatalyst for NO reduction to NH_(3)

Electrochemical reduction of NO offers us an attractive alternative to traditional selective catalytic reduction process for harmful NO removal and simultaneous NH_(3)production,but it requires efficient electrocatalyst to enable the NO reduction reaction with high selectivity.Here,we report on the development of Bi nanoparticles/carbon nanosheet composite(Bi@C)for highly effective NO reduction electrocatalysis toward selective NH_(3)formation.Such Bi@C catalyst attains an impressive NH_(3)yield of 1,592.5μg·h^(−1)·mgcat.^(−1)and a high Faradaic efficiency as high as 93%in 0.1 M Na_(2)SO_(4)electrolyte.Additionally,it can be applied as efficient cathode materials for Zn–NO battery to reduce NO to NH_(3)with high electricity generation.