Search

A conductive MOF Cu3(HHTP)2 is introduced as a non-noble metal co-catalyst into a Tp-Pa-2-COF to construct an efficient hydrogen evolution system.

Designing recyclable photocatalysts with high activity and stability has drawn considerable attention in the fields of sewage treatment. Herein, a series of heterojunctions constructed by zirconium-based metal–organic frameworks (UiO-66-NH2) and tungsten trioxide (WO3) is immobilized on carbon cloth via a facile solvothermal method, resulting in highly recyclable photocatalysts. Multiple characterization techniques, such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy, verify the successful synthesis of UiO-66-NH2 nanospheres on the surface of needlelike WO3 modified carbon cloth. Results show that the optimal heterojunction photocatalyst exhibits excellent photocatalytic degradation efficiency for the removal of tetracycline (TC) from water, for which nearly 100% of TC is degraded within 60 min under visible light. Trapping experiments and electron spin resonance (ESR) spectra analyses demonstrate that the superoxide radicals O2– and photogenerated hole h+ play a dominant role in the degradation process. Excellent photocatalytic activity is dominantly attributed to the effective separation of photoinduced carriers in this type-Ⅱ heterostructure system. Moreover, the possible photocatalytic oxidation degradation pathway is confirmed by analyzing intermediates using liquid chromatography mass spectrometry (LC-MS). This study offers a highly efficient strategy to design recyclable heterojunction photocatalysts for the degradation of refractory antibiotics in sewage.

Molybdenum disulfide (MoS2) with a graphite-like layer structure has attracted substantial interest as an anode material for sodium ion batteries (SIBs), but its inherent poor electrical conductivity and slow sodium ion transportation are the two important factors that limit its use in SIBs. Here, we report a general approach to synthesize a series of molecule-intercalated MoS2 with a precisely controlled interlayer distance of 0.62 to 1.24 nm in which the electrical conductivity could be also widely and finely adjusted from 1.3 × 10-4 to 3.5 × 10-2 S cm-1 via the insertion of different molecules. By adjusting the interlayer space and enhancing the electrical conductivity, the highest initial sodium ion storage capacity of 465 mA h g-1 (vs 195 mA h g-1 for the pure MoS2 anode) and the highest capacity of 420 mA h g-1 (vs 31 mA h g-1 for the pure MoS2 anode) after 600 cycles at a rate of 100 mA g-1 were obtained. The excellent performance is credited to the rapid Na+ and electron transport and higher material utilization derived from the synergistic effect of the expanded interlayer space and the higher electronic conductivity. The results provide some inspiration for the design and construction of superior layered anode materials for sodium-ion batteries.

In this study, metal-organic frameworks (MOF)/polyacrylonitrile (PAN) composite fibrous separators were prepared for high-rate Li-ion batteries by anchoring MOF into PAN nanofibrous network. The MOF/PAN separators possess excellent dimensional, thermal stability, intrinsically high porosity, and good electrolyte adsorption, which contribute excellent Li-ion transport capacity. The Li/Li symmetric cells assembled with MOF/PAN separators demonstrate improved coulombic efficiency, inhibition of Li dendrites, and excellent long-term cycle stability with low-voltage hysteresis of around 46 mV after more than 1200 h Li plating/stripping process, in comparison with around 350 mV after 360 h for commercialized Celgard 2400 separator. The excellent ionic transport capacity reveals impressive performance of the LiFePO4-MOF/PAN-Li metal full cells under high rate and the capacity that could be up to 104 mAh g−1 at 5 C after 2000 cycles with a coulombic efficiency of almost 100%. This work provides a new prospect for the development of high-rate lithium-ion batteries.

Metal–organic frameworks (MOF) have attracted great attention in the field of wastewater treatment. When MOF nanoparticles are used for adsorption applications, the nanoparticles normally have to be separated from the dispersed suspension by filtration or centrifugation for regeneration or recycling. In order to avoid this costly and time consuming process, MOF (NH2-MIL-125) nanofibrous hybrid membranes with photocatalytic properties were successfully fabricated in this study. The MOF membranes were characterized by using XRD, SEM, FTIR, TGA, BET, and UV–Vis. The adsorption (including capacity, mechanism, dynamic, and isotherm) of dyes by the membranes is studied in great detail. The membranes exhibit great adsorption capacity to methylene blue and sodium fluorescein, and the adsorption is dominated by steric hindrance of dye molecule, not the π–π interactions and the zeta potential. Most importantly, the MOF membranes could be easily separated from the dyes solution and regenerated via a visible light catalytic degradation process for recycling, and the photocatalytic mechanism is discussed.

Conjugated quinones are promising cathode materials for sodium-ion batteries. However, the contemporary primary conjugated quinones cathodes still hold to limited capacity, poor rate performance and low cyclability, due to the poor electronic and ionic conductivity. Herein, a series of high-performance conjugated-quinones@MXene hybrid cathodes is constructed by an in situ polymerization-assembly strategy based on the hydrogen bond and S-Ti interaction. The PAQS@Ti

Construction of porous metal-organic framework (MOF)/covalent organic framework (COF) hybrid photocatalysts for enriched structures and unprecedented properties is still a great challenge but highly desirable. Herein, a new series of Cu

The practical application of lithium–sulfur batteries has been restricted by the low operating rates and the low areal sulfur loading, resulting from the insulating and dissolving nature of sulfur and lithium polysulfides. Herein, we propose a “boxes in fibers” strategy and build a hierarchical three-dimensional conductive network, which is based on necklace-like N-doped carbon nanofibers with threaded hollow carbon nanoboxes and TiC nanoparticles (CNB–TiC@CNF), via a facile electrospinning process. Ideally, a large amount of sulfur could be loaded in the hollow cavities of CNBs and the pores of CNFs, with physically/chemically active sites, while the interconnected conductive network is beneficial for fast Li+ diffusion and electron transfer. Depending on the hierarchical and porous framework, the volume variation of the lithium polysulfides can be further alleviated. The as-constructed CNB–TiC@CNF with enhanced adsorption and conversion ability to polysulfides achieves a high discharge capacity of 1611 mA h g−1 at 0.1C, high-rate performance up to 10C for 400 cycles with a decay rate of 0.15% and high sulfur areal loading performance with a stable areal capacity of 7.90 mA h cm−2 at 9.2 mg cm−2. Our work provides a novel and efficient strategy for the construction of a three-dimensional hierarchical host as a high-performance cathode for lithium–sulfur batteries.

Selenium has received increasing attention as a potential alternative to sulfur cathode for rechargeable lithium batteries because of its high electronic conductivity and better electrochemical performance. However, the shuttle effect of polyselenides in lithium-selenium batteries, similar to that of polysulfides in lithium-sulfur batteries, is still one of the main drawbacks. Here, we designed and synthesized a new pomegranate-like porous carbon/Se (PPC/Se) cathode that could effectively improve the shuttle effect of polyselenides. The pomegranate-like carbon nanoparticles used as the host materials for Se were prepared via carbonization of well-assembled ketjen black nanosubunits. The batteries assembled with such new-synthesized PPC/Se cathodes exhibit relatively high specific capacity of 380 mA h g−1 at 1 C and high Coulombic efficiency of ∼ 98% due to the restrained dissolution of polyselenides.

The practical application of Lithium Sulfur battery is limited due to its rapid capacity fading and early battery failure caused by the shuttling of soluble polysulfide. Thus, the key to improve the performance of a Lithium Sulfur battery is to suppress the shuttling effect. Herein, we report a NbN modified PP separator with high performance for Lithium Sulfur battery applications. The NbN functionalized layer of the separator can strongly interact with soluble polysulfide species, as demonstrated by both experimental investigation and theoretical verification. As a result of the high polysulfide affinity, the composite separator effectively prevents the shuttling of soluble polysulfide through the separator. Besides, the high electrolyte wettability of NbN modification layer lowers the resistance of Li+ transport through the separator. Due to these favorable features, Lithium Sulfur battery assembled with the multifunctional NbN modified separator exhibits excellent cycling performance with a reversible capacity of 554.6 mAh g−1 after 200 cycles at 0.2C. The significantly improved rate performance of the battery based on the modified separator is also demonstrated. Our results show that NbN is a promising material for the modification of separators in Lithium Sulfur battery and the strategy of separator engineering is effective for improving the performance of Lithium Sulfur battery.

Designing recyclable photocatalysts with high activity and stability has drawn considerable attention in the fields of sewage treatment. Herein, a series of heterojunctions constructed by zirconium-based metal-organic frameworks (UiO-66-NH

Molybdenum disulfide (MoS

Metal-organic frameworks (MOFs) provide a novel strategy to precisely control the alignment of molecules to enhance exciton diffusion for high-performance organic semiconductors. In this paper, we characterize exciton dynamics in highly ordered and crystalline porphyrin MOF nanofilms by time-resolved photoluminescence and femtosecond-resolved transient absorption spectroscopy. Results suggest that porphyrin MOF nanofilms could be a promising candidate for high-performance organic photovoltaic semiconductors in which the diffusion coefficient and diffusion length of excitons are 9.0 × 10-2 cm2 s-1 and 16.6 nm, respectively, comparable with or even beyond that of other excellent organic semiconductors. Moreover, by monitoring real-time exciton dynamics it is revealed that excitons in MOF nanofilms undergo high-efficient intermolecular hopping and multiexciton annihilation due to the short intermolecular distance and aligned molecular orientation in MOF structure, thus providing new insights into the underlying physics of exciton dynamics and many-body interaction in molecular assembled systems.

A new type of TiO2 photoanode containing upconversion luminescence materials Y2O3:Er3+ nanorods is developed, which is effective to enhance the photoelectric conversion efficiency of dye-sensitized solar cell. The Y2O3:Er3+ nanorods are synthesized using a hydrothermal process and the photoandodes are prepared via coating the TiO2 (P25) and Y2O3:Er3+ mixture with various Y2O3:Er3+ concentrations on the fluorine doped tin oxide (FTO) substrates. We show that the TiO2 photoanode with an Y2O3:Er3+ concentration of 4% exhibits the highest photoelectric conversion efficiency (7.80%), which is 43.6% higher than that of the pure P25 photoanode (5.43%). This great enhancement is attributed to the additional, useful photons converted from infrared (IR) photons in sun light by the doped Y2O3:Er3+ upconversion nanorods. In addition, the electrochemical impedance spectroscopy (EIS) analysis demonstrates that the doping of Y2O3:Er3+ improves the charge transfer and electron lifetime of the dye-sensitized solar cell.

Nanoporous metal–organic frameworks (MOFs) equipped with light-responsive azobenzene pendant groups present a novel family of smart materials, enabling advanced applications like switchable guest a...

Room-temperature Na-ion batteries have been widely used as promising energy storage systems for large-scale storage due to the nature abundance and low cost of Na. However, the search for an anode with appropriate Na storage and high structural stability still remains challenging. In this work, the carbon microsphere films-coated Ni foam is prepared by a simple chemical vapor deposition method and is used as a novel anode for the long-lifespan Na-ion batteries. These carbon microspheres possess special onion-like structures that enhance the Na-ions intercalation and exhibit excellent Na storage properties. In addition, directly coating the carbon microsphere films on Ni foam current collectors without binders and conductive additives results in an integrated electrode structure, which avoids the undesirable interfaces and reduces the packaging volume. Compared to the common used hard carbon anode with long discharge plateau and short lifespan, this integrated electrode exhibits a slope discharge profile with higher security and demonstrates a long lifespan of 700 cycles with a high capacity retention of 83%. Furthermore, the storage mechanism of sodium ion is also investigated in detail by ex situ Raman, X-ray diffraction and nuclear magnetic resonance techniques in this study.

Development of surface coatings with high antimicrobial activity is urgently required to fight bacteria and other microorganisms on technical and hygiene relevant surfaces. Control over structure and topology of the surface coatings, combined with the ability to include functional molecules within the structure, is crucial for optimizing their performance. Herein, we describe a novel strategy to synthesize structurally well-defined porphyrin polymer thin films via a template approach. In this approach, bisazido-functionalized porphyrin molecules are preorganized within a metal-organic framework (MOF) structure. Afterward, porphyrin units within the MOF are covalently connected via a secondary linker. Removal of the metal ions of the MOF results in water-stable porphyrin polymer thin films that demonstrate high antibacterial activity against pathogens via visible-light-promoted generation of reactive oxygen species. In addition, this approach offers the inherent possibility to incorporate guest molecules within the structures, to functionalize the surface with biomolecules, and to create hierarchically structured materials.

Benefitting from the strong intrinsic nonlinear optical (NLO) property of the individual porphyrin molecule, the integration of porphyrin molecules into tightly aligned arrays may lead to intuitively promising high-performance materials of tailorable NLO effect. In order to verify this speculation, we prepare crystalline and highly oriented porphyrin-based surface-supported metal-organic framework nanofilms (SURMOFs) and then characterize their NLO performance. Results reveal that porphyrin-based SURMOFs exhibit the highest saturable absorption (SA) yet recorded with a third-order NLO absorption coefficient up to -10-3 cm/W, about 7 orders stronger than porphyrin solvents in which the porphyrin molecules are disordered, under a certain excitation strength. Further increasing the excitation strength shows that the NLO absorption property of the porphyrin-based SURMOFs can be effectively modulated from SA to reverse saturable absorption, followed by a reemerging SA. The multiple-stage NLO switching is assigned to the interplay of simultaneous one-photon SA, two-photon absorption, and two-photon SA effects. The superior and modulatable NLO property as well as the designable and ordered crystalline structure suggest that porphyrin-based SURMOFs might be employed as a new class of high-performance NLO materials with potential applications in novel optical switches or logic gates to realize the all-optical information process.

The development of efficient heterogeneous catalysts for fine chemical synthesis is critical for practical applications. Herein, for the first time, the zirconium-based metal-organic framework (UiO-66-NH2) is applied as an efficiently heterogeneous photocatalyst for conversion of benzyl halides to corresponding aldehydes with high selectivity (about 80 %) and conversion (up to 99 %) in the presence of oxygen and DMF as solvent. Through a series of experiments and analysis, the reaction mechanism is proposed to involve nucleophilic attack of the N-oxide. This study provides a general, environmental and high selective method to prepare benzaldehydes and broadens the application fields of UiO-66-NH2.

Die magnetischen Eigenschaften Metall-organischer Geruste (MOFs) der SURMOF-2-Serie wurden untersucht. Anders als bei Volumen-MOF-2-Kristallen, bei denen Cu2+-Ionen in einer Schaufelrad-Anordnung vorliegen und antiferromagnetisch gekoppelt sind, zeigen die Carboxylatgruppen hier eine reisverschlussartige Anordnung. Eine theoretische Analyse ergibt, dass diese ungewohnliche Kopplung der Spin-1/2 -Ionen innerhalb der entstehenden, eindimensionalen Ketten bei niedriger Temperatur eine ferromagnetische Phase (FM-Phase) stabilisiert. Anders als bei anderen geordneten 1D-Systemen sind zum Induzieren des Ferromagnetismus keine starken Magnetfelder erforderlich. Die Konstanten der magnetischen Kopplung zur Beschreibung der Wechselwirkung zwischen den einzelnen Metallionen wurden in SQUID-Versuchen bestimmt. Sie stimmen ausgezeichnet mit den Ergebnissen von Ab-initio-DFT-Elektronenstruktur-Berechnungen uberein. Die theoretischen Ergebnisse ermoglichen eine detaillierte Beschreibung des ungewohnlichen Verhaltens dieses exotischen, aber dennoch leicht herstellbaren Materials.

We have studied the magnetic properties of the SURMOF-2 series of metal-organic frameworks (MOFs). Contrary to bulk MOF-2 crystals, where Cu(2+) ions form paddlewheels and are antiferromagnetically coupled, in this case the Cu(2+) ions are connected via carboxylate groups in a zipper-like fashion. This unusual coupling of the spin 1/2 ions within the resulting one-dimensional chains is found to stabilize a low-temperature, ferromagnetic (FM) phase. In contrast to other ordered 1D systems, no strong magnetic fields are needed to induce the ferromagnetism. The magnetic coupling constants describing the interaction between the individual metal ions have been determined in SQUID experiments. They are fully consistent with the results of ab initio DFT electronic structure calculations. The theoretical results allow the unusual magnetic behavior of this exotic, yet easy-to-fabricate, material to be described in a detailed fashion.

Surface Anchored Metal-organic-framework (SURMOF) films are designed quasi-crystalline compounds that consists of metal ions connected by organic ligands, forming highly ordered porous structures. The SURMOF films initially were considered to have limited applications in electronic devices because of their insulating character. Recently, several approaches were found to tune the electrical conductivity of MOFs [1]. One of the effective methods found is to infiltrate guest molecules inside the porous framework to transport ions, and hence to modulate the electrical properties of the host framework. MOF Cu3(BTC)2 (BTC: benzene tricarboxylate) is a typical MOF film known as HKUST-1 (Hong Kong University of Science and Technology 1). Its electrical conductivity could increase up to 7 orders of magnitude by introducing tetracyano-quinodimethane (TCNQ) guest molecules. Recently MOFs films received more attention in the fields of switching nanodevices [2], sensors, and thermoelectrics. reported MOF films loaded with TCNQ@Cu3(BTC)2 exhibiting high Seebeck coefficients and low thermal conductivity [3]. However, the low electrical conductivity reduces the figure of merit ZT of MOFs. In this work we present alternating MOF/PbTe and MOF/PbSe nanolaminate structure synthesized by alternately depositing SURMOF films and lead chalcogenide films. The SURMOFs were fabricated by liquid phase epitaxy (LPE) technique. Ethanoic solution of copper acetate hydrate (1mM) and organic linker solution (1, 3, 5-benzenetricarboxylic acid) (0.2mM) were used as precursors for HKUST-1 MOFs. TCNQ was loaded to modulate electrical conductivity of MOFs. PbTe and PbSe were synthesized on the top of MOFs by thermal ALD technology. Lead bis(2,2,6,6-tetramethyl-3,5-heptanedionato) (Pb(C11H19O2)2), (trimethylsilyl) telluride ((Me3Si)2Te) and (trimethylsilyl) selenide ((Me3Si)2Se) were employed as the chemical ALD precursors for lead, telluride and selenide, respectively. 20 sccm N2 was used as a carrier gas to transport the chemical precursors into the ALD reaction chamber. The ALD growth temperature was 150 ˚C. The solid lead precursor was volatilized at a temperature of 170 ˚C, the liquid Te precursor required heating to 40 ˚C, and the liquid Se precursor was kept at room temperature. The chamber base pressure was kept at 30 mTorr. Composite nanolaminate structure of MOF/PbTe and MOF/PbSe with film thickness of 10 nm/ 10 nm, 20 nm/ 20 nm, and 60 nm/ 60 nm were fabricated and investigated. Several physical characterization techniques have been employed to determine the surface characters of the sample. The samples were characterizated by X-ray diffraction (XRD) for film crystal structure, and by field emission scanning electron microscopy (FE-SEM) for film morphology and structure. For thermoelectrical properties of the sample, Seebeck coefficient both in vertical and horizontal directions were measured. Electrical conductivity and thermal conductivity of the films were investigated as well to envaluate ZT value of the samples. Figure 1 shows the IV characteristics of MOF films loaded with TCNQ. The linear IV curve indicates Ohmic conduction in TCNQ loaded MOFs. Figure 2 displays the Seebeck coefficient of TCNQ loaded MOF films over a temperature range of 290 K ~330 K. The maximum Seebeck coefficient of the film occurs at 290 K and the positive Seebeck coefficient reveals positive charge carriers in the MOF film. References: 1. Talin, A.A., et al., Tunable electrical conductivity in metal-organic framework thin-film devices. Science, 2014. 343(6166): p. 66-69. 2. Wang, Z., et al., Resistive Switching Nanodevices Based on Metal–Organic Frameworks. ChemNanoMat, 2016. 2(1): p. 67-73. 3. Erickson, K.J., et al., Thin Film Thermoelectric Metal–Organic Framework with High Seebeck Coefficient and Low Thermal Conductivity. Advanced Materials, 2015. 27(22): p. 3453-3459. Figure 1

Carboxyl functionalized magnetic cores coated homogeneously with UiO-67 metal–organic frameworks (MOFs) through a liquid phase epitaxy (LPE) process are introduced. Using the as-synthesized core–shell microparticles as stationary phase in HPLC runs with different phenol derivatives, good separation efficiencies can be achieved when applying an acetonitrile/water mobile phase. To understand the advantages and limitations of such MOF based stationary phases in more detail, the experimental elution profiles are compared with simulations from a powerful chromatography modeling software (ChromX) newly developed at the KIT. The simulation results reveal that the affinities of UiO-67 to the tested phenol derivatives strongly differ (2,6-dimethylphenol −1 . The uptake kinetics are dominated by intraparticle diffusion while axial dispersion and film diffusion play only minor roles. The pore diffusivities of the phenol derivatives are found to be around 1.3 ⋅ 10 −13 m 2 s −1 . Based on single component data, the successful simulation of multicomponent isocratic pulse experiments is demonstrated. In summary, HPLC runs combined with in-depth modeling are a powerful tool to investigate the interactions between solute molecules and thin MOF films, and to reveal data about affinities, capacities and uptake kinetics.

SURMOF (surface-anchored metal–organic frameworks) thin films exhibit exciting chemical and physical properties, which can be modulated in a straightforward fashion to achieve specific benefits for numerous applications in future technologies. Here, we report a detailed characterization of resistive switching in crystalline SURMOF films of around ≈10, ≈20 and ≈50 nm thicknesses. These demonstrated switching characteristics combined with the ability to deposit monolithically oriented crystalline HKUST-1 films with well-defined thicknesses in the nm-range on conductive substrates serving as bottom electrodes and to lithographically fabricate top-electrodes opens up the possibility to employ these metal–organic hybrid materials as solid state devices for potential nonvolatile resistive random access memory (RRAM) memory applications. MOF bipolar switching RRAM devices based on SURMOFs with thicknesses of 10±5 nm, 20±5 nm and 50±5 nm show exceptionally promising performance. The huge flexibility of MOF materials with regards to device applications is demonstrated by loading guest molecules into the pores of these framework materials. In the case of ferrocene infiltration, we show that the already impressive performance of the SURMOF-RRAM devices can be further improved. The results demonstrate the great potential of SURMOF thin films for the implementation of novel and scalable active materials for the next generation of digital processing and organic-based microelectronic devices.

Metal–organic frameworks, MOFs, are a class of crystalline porous metal–organic hybrid materials which have originally been developed for applications in gas storage and separation. Here, we demonstrate that due to the enormous chemical flexibility of these molecular materials, they also provide an excellent basis for the development of photoresist materials. In particular, we used an epitaxial process with automated systems to grow either homogeneous or patterned SURMOFs (surface-anchored MOFs) of the type [Zn2(N3BPDC)2(Dabco)] on different solid substrates. The huge flexibility of the MOF chemistry allowed for different variants of photolithography based on the post-synthesis modification (PSM) of the MOF materials. Here, two particular and popular PSM-strategies were employed, the azide–alkyne click reaction and thiol–yne click chemistry. The azide–alkyne click reaction was initiated by the photoreduction of CuII to the active CuI catalyst, whereas the thiol–yne click chemistry was induced directly by UV light. Furthermore, heteroepitaxial growth of multilayer systems (Cu-N3BPDC+Cu-BPDC+Cu-N3BPDC+Cu-BPDC+Cu-N3BPDC+Cu-BPDC) was also used to control the localization of subsequent PSM. The results demonstrated that the patterned functionalization of MOF thin film is not limited to the two dimensions of the mounting surface but is indeed possible in 3D.

Bei anorganischen Halbleitern fuhrt kristalline Ordnung zur Bildung einer elektronischen Bandstruktur, die deutliche Unterschiede zu ungeordnetem Material aufweist; z. B. konnen indirekte Bandlucken auftreten. Bei organischen Halbleitern werden solche Effekte ublicherweise nicht in Betracht gezogen, da die Bander in der Regel flach sind und die Bandlucke daher direkt ist. Wir prasentieren hier genaue Berechnungen der elektronischen Struktur, die zeigen, dass geordnete Porphyrinstrukturen eine geringe Dispersion besetzter und nichtbesetzter Bander aufweisen, was die Bildung einer kleinen indirekten Bandlucke zur Folge hat. Wir haben solche geordneten Strukturen experimentell mithilfe der Flussigphasenepitaxie hergestellt und weisen nach, dass die entsprechenden kristallinen organischen Halbleiter uber verbesserte photophysikalische Eigenschaften, z. B. eine hohe Ladungstragermobilitat und hohe Effizienz der Erzeugung von Ladungstragern, verfugen. Das grose Potenzial dieses neuartigen Materials demonstrieren wir anhand eines effizienten organischen Photovoltaiksystems.

The metal organic framework (MOF) UHM-3, constructed with Cu(II)-paddle wheel-type nodes and a new tetracarboxylic acid linker, 5,5′-(dimethylsilanediyl)diisophthalate, has a close-packed alignment of open Cu(II) sites which are of interest for applications in gas storage and separation. Here, we first report on the growth of oriented, homogeneous and virtually defect-free (below 1%) UHM-3 MOF thin films on a solid substrate using a room-temperature liquid phase epitaxy (LPE) method. Thermal postsynthetic treatment allowed to induce Cu(I) defect sites in a controlled fashion. The interaction of CO and CO 2 with the Cu(II) and Cu(I) sites was then studied using X-ray photoelectron spectroscopy (XPS) and IR-spectroscopy. The binding energy of these two species was determined using temperature-induced desorption. The interaction between the guest molecules and the Cu(I) and Cu(II) sites were also analyzed using density-functional theory (DFT). Surprisingly, both experiment and theory show that the binding energy of CO 2 to Cu(I) and Cu(II) sites are essentially identical, in pronounced contrast to CO, which binds much stronger to Cu(I).

We report the fabrication of monolithic dielectric mirrors by stacking layers of metal–organic frameworks (MOFs) and indium tin oxide (ITO). Such Hybrid Photonic Band-Gap (PBG) Materials exhibit high optical quality (reflectivities of 80%) and are color tunable over the whole visible range. While the ITO deposition is accomplished by using a conventional sputter process, the highly porous MOF layers are deposited using liquid-phase epitaxy (LPE), therefore yielding crystalline, continuous, and monolithic HKUST-1 SURMOF thin films with high optical performance. We demonstrate the optical sensing capabilities of these monolithic and porous Bragg stacks by investigating the chemo-responsive optical properties (PBG shift and modulation of the intensity of the PBG maximum) upon the exposure to different organic solvents.

Achieving high values for proton conductivity in a material critically depends on providing hopping sites arranged in a regular fashion. Record values reported for regular, molecular crystals cannot yet be reached by technologically relevant systems, and the best values measured for polymer membranes suited for integration into devices are almost two orders of magnitude lower. Here, an alternative polymer membrane synthesis strategy based on the chemical modification of surface-mounted, monolithic, crystalline metal-organic framework thin films is demonstrated. Due to chemical crosslinking and subsequent removal of metal ions, these surface-mounted gels (SURGELs) are found to exhibit high proton conductivity (0.1 S cm-1 at 30 °C and 100% RH (relative humidity). These record values are attributed to the highly ordered polymer network structure containing regularly spaced carboxylic acid side groups. These covalently bound organic frameworks outperform conventional, ion-conductive polymers with regard to ion conductivity and water stability. Pronounced water-induced swelling, which causes severe mechanical instabilities in commercial membranes, is not observed.

Oriented circular dichroism (OCD) is explored and successfully applied to investigate chiral surface-anchored metal-organic frameworks (SURMOFs) based on camphoric acid (D- and Lcam) with the composition [Cu2(Dcam)(2x)(Lcam)(2-2x)(dabco)]n (dabco = 1,4-diazabicyclo-[2.2.2]-octane). The three-dimensional chiral SURMOFs with high-quality orientation were grown on quartz glass plates by using a layer-by-layer liquid-phase epitaxy method. The growth orientation, as determined by X-ray diffraction (XRD), could be switched between the [001] and [110] direction by using either OH- or COOH-terminated substrates. These SURMOFs were characterized by using OCD, which confirmed the ratio as well as the orientation of the enantiomeric linker molecules. Theoretical computations demonstrate that the OCD band intensities of the enantiopure [Cu2(Dcam)2(dabco)]n grown in different orientations are a direct result of the anisotropic nature of the chiral SURMOFs. Finally, the enantiopure [Cu2(Dcam)2(dabco)]n and [Cu2(Lcam)2(dabco)]n SURMOFs were loaded with the two chiral forms of ethyl lactate [(+)-ethyl-D-lactate and (-)-ethyl-L-lactate)]. An enantioselective enrichment of >60 % was observed by OCD when the chiral host scaffold was loaded from the racemic mixture.

The ramified growth of lithium dendrites and their enormous volume change upon cycling bear the primary responsibility for the poor cyclability and serious safety of lithium metal batteries. Herein, a low volume change composite lithium metal anode is realized by encaging Li into a hybrid host featuring a 3D conducting scaffold with a metal-organic frameworks (MOFs) coating. The scaffold with high pore volume is favorable to accommodate Li with high areal capacity and alleviate the variation in electrode dimensions. The MOFs layer with abundant interconnected micropores serving as “ion sieve” can boost uniform distribution of Li ions while its high Young's modulus (>32 GPa) can arrest dendrite propagation. The thus-formed anode displays a negligible dimension variation ( 1000 h) and full cells (>200 cycle-life). This study may open up new directions to construct safe Li metal batteries through an industry-adoptable technology.

A novel three-dimensional (3D) Cs 2.5 H 0.5 PW 12 O 40 -Nafion electrolyte materials are designed by impregnatingCs 2.5 H 0.5 PW 12 O 40 ( m phosphotungstic acid : m Cesium carbonate =50:7) into the 3D ordered Nafion matrixes, which are synthe-sized by monodisperse poly(methyl methacrylate) (PMMA) colloidal crystal template with subsequent removalof the organic template by solvent extraction. The results show that the reconstruction of the Nafion elec-trolyte to a 3D well-organized porous matrix form highly ordered proton transportation pathway, resulting inthe improvement of the proton conductivity at high temperature and the Cs 2.5 H 0.5 PW 12 O 40 proton carriers in thechannels also play an assistant role in enhancing the proton conductivity. Furthermore, the spillover effect of theCs 2.5 H 0.5 PW 12 O 40 proton carriers effectively increases the electrochemical activity of the membrane electrode,lowers the interface impedance and improves the fuel cell performance.KEYWORDS: PEM Fuel Cell, Proton Exchange Membrane, 3D Ordered Nafion Matrix, Cs

In this work, we developed a novel composite membrane by anchoring perfluorosulfonic acid into the hydrophilic poly(lactic-co-glycolic acid) (PLGA) nanofibrous network which was synthesized by electrospinning method. It was clear that the PLGA/Nafion composite membranes possessed high Nafion loading, excellent dimensional stability and proton transport capacity. When the humidity of the membrane changed from soaking in water to 25 RH% at 90 °C, the PLGA fiber network effectively controlled the swelling of Nafion resin and reduced the humidity-generated shrinkage stress from 2.2 MPa (Nafion211 membranes) to 0.5 MPa (PLGA/Nafion composite membranes). The proportion of humidity-induced stress to the yield strength was also reduced to 4.4%, in comparison to 21.2% of that of Nafion211 membrane. The area proton conductivity of the PLGA/Nafion composite membrane achieved 48.2 S cm−2, compared with 36.0 S cm−2 of Nafion211 membranes in the same condition. The excellent proton transport capacity greatly improved the performance of fuel cell assembled with PLGA/Nafion composite membranes and effectively reduced the dynamic response time from 22 s (Nafion211 membranes) to 7 s (PLGA/Nafion composite membranes).