Unsaturated Zn Research Articles

Insights into Amorphous Metal‐Organic Framework as Carbonic Anhydrase Mimic

AbstractCarbonic anhydrase (CA) is an important enzyme which breaks the C−O bond and catalyzes the hydration of CO2 and developing artificial enzyme to mimic the function of CA is important for the related applications. Zeolitic imidazolate frameworks (ZIFs) with typical tetrahedral Zn−N coordination units which were similar to the catalytically active site of natural CA have been reported to displayed CA‐like activities. However, the activity of crystalline ZIFs remains unsatisfactory. Herein, amorphous zeolitic imidazolate framework (aZIF) was fabricated through a facile self‐assembly process and exhibited 2.2‐fold higher CA‐like hydrolytic activity than the corresponding crystalline ZIF‐8.This phenomenon can be ascribed to the unsaturated Zn−N coordination structure and mesopores inside aZIF. This work affords a new avenue for the rational design of nanozymes.

A mechanistic evaluation for total removal of toxic hexavalent and trivalent chromium from water by oxygen vacancy-engineered nanocomposite

Oxygen vacancy-engineered nanocomposites are emerging materials in adsorption and photocatalysis research. This study evaluated total toxic Chromium removal by a nanocomposite of core-shell zeolite A@oxygen-vacant ZnO1−X (ZA@ZnO1−X) from water using its coexisting dual characteristics. ZA@ZnO1−X has removed 98.3% of total Cr, achieving a discharge limit of 0.05 ppm of Cr(VI) after the photoreduction and adsorption simultaneously. The detailed structural and physicochemical properties of synthesized ZA@ZnO1−X nanocomposite show higher BET surface area, oxygen-vacant percentage, and visible light photoactivity than the sole ZnO1−X nanosheet. The photocatalytic reduction efficiency (PRE) effect is systematically studied on varying operational variables like pH, citric acid (CA), Cr(VI) concentration, catalyst load, presence of anions, and radical scavengers. ZA@ZnO1−X removed Cr(VI) and Cr(III) simultaneously by 98.5% PRE with a catalyst load of 4 g/l, CA= 5 mM, pH= 5.06 under halogen light irradiation (300 W, 240 V) for 50 mins. This experimental study evaluates the prominent role of oxygen vacancy of ZA@ZnO1−X for photocatalytic reduction of Cr(VI) and enhanced adsorption of Cr(III). The kinetic study reveals adsorption of both Cr(VI) and Cr(III) follows pseudo-second-order kinetics, whereas photoreduction of Cr(VI) follows pseudo-first-order kinetics. A possible mechanism of total Cr removal is sketched, supporting enhanced adsorption due to unsaturated Zn atoms and unpaired e- at the oxygen defect site, followed by photoreduction by photogenerated e- and CO2-• radical. The ZA@ZnO1−X performance is reduced by only 2.5% after five consecutive runs without deformation. The easy regeneration process makes it suitable for toxic total Cr removal, avoiding any secondary pollution.

Amplified circularly polarized luminescence of chiral metal-organic frameworks via post-synthetic installing pillars

Post-synthetic installation strategy is an effective approach to improve the functions of metal-organic frameworks (MOFs). Herein, a pair of chiral MOFs is successfully constructed through solvothermal subcomponent self-assembly and exhibit circularly polarized luminescence (CPL). These MOFs contain coordinatively unsaturated Zn sites and channels, which allow the installation of pyridyl-terminated pillars into the original structure. Such a post-synthetic installation process reinforces the MOFs’ rigidity and increases the photoluminescence quantum yields (PLQYs). Furthermore, the luminescence dissymmetry factors (glum) of these post-modified MOFs are amplified after installing the pillars. This work provides an appealing strategy for boosting the CPL performance of chiral MOFs.

High-Density Coordinatively Unsaturated Zn Catalyst for Efficient Alkane Dehydrogenation.

The exploration of non-noble metal catalysts for alkane dehydrogenation and their catalytic mechanisms is the priority in catalysis research. Here, we report a high-density coordinatively unsaturated Zn cation (Zncus) catalyst for the direct dehydrogenation (DDH) of ethylbenzene (EB) to styrene (ST). The catalyst demonstrated good catalytic performance (∼40% initial EB conversion rate and >98% ST selectivity) and excellent regeneration ability in the reaction, which is attributed to the high-density (HD) distribution and high-stability structure of Zncus active sites on the surface of zinc silicate (HD-Zncus@ZS). Density functional theory (DFT) calculations further illustrated the reaction pathway and intermediates, supporting that the Zncus sites can efficiently activate the C-H bond of ethyl on ethylbenzene. Developing the high-density Zncus catalyst and exploring the catalytic mechanism laid a good foundation for designing practical non-noble metal catalysts.

Highly Flexible Carbon Film Implanted with Single‐Atomic Zn−N2 Moiety for Long‐Life Sodium‐Sulfur Batteries

AbstractRoom‐temperature sodium‐sulfur (RT Na–S) batteries are regarded as one of promising next‐generation energy storage systems owing to the high theoretical energy density (1274 Wh kg−1) and rich abundance of the raw materials. However, the sluggish redox kinetics and low electrical conductivity of sulfur (S) cathode significantly imped their practical application. Herein, a flexible carbon film implanted with single‐atomic Zn−N2 moiety (Zn‐N2/CF) is constructed as the efficient S host material to effectively improve the redox kinetics and electrical conductivity. The theoretical and experimental results show that, compared to Zn−N4 center, unsaturated Zn−N2 center with asymmetric electron distribution has significant advantages in anchoring and activating sodium polysulfides to accelerate the conversion from S8 to Na2S and reducing the reaction energy barrier of Na2S decomposition. Consequently, Zn‐N2/CF/S can retain a reversible capacity of 838.5 mAh g−1 at 0.1 A g−1 after 100 cycles, which is higher than that of Zn‐N4/CF/S (688.0 mAh g−1). Moreover, Zn‐N2/CF/S also maintains a long‐term cycling performance with a negligible capacity decay rate of 0.006% per cycle over 4000 cycles at 10 A g−1. This work provides an effective strategy to obtain the flexible carbon film implanted with unsaturated single‐atomic structure, thereby ultimately resulting in high‐performance RT Na–S batteries.

Statement of Retraction: Cyanosilylation of aldehydes catalyzed by a porous metal-organic framework containing a coordinatively unsaturated Zn(II) center and its anticancer activity in human osteogenic sarcoma

This article refers to:Cyanosilylation of aldehydes catalyzed by a porous metal-organic framework containing a coordinatively unsaturated Zn(II) center and its anticancer activity in human osteogenic sarcoma

Flotation separation of molybdenite from sphalerite using dl-cysteine as a depressant and insight into its selective adsorption mechanism

dl-cysteine (DLC) was investigated as an eco-friendly and nontoxic sphalerite depressant in the flotation separation of molybdenite from sphalerite. Micro-flotation tests were carried out to study the flotation performance of sphalerite and molybdenite treated by DLC, and the selective depression mechanism of DLC on sphalerite was systematically explored using various characterizations. Flotation experiments indicated that DLC can selectively depress sphalerite in a wide range of pH, and its effect on the floatability of molybdenite was negligible. Zeta potential, Fourier infrared, and adsorption density analyses indicated that DLC was more inclined to be adsorbed on the sphalerite surface than on the molybdenite surface. The pre-adsorbed of DLC further hindered the subsequent adsorption of butyl xanthate on the sphalerite surface. X-ray photoelectron spectroscopy illustrated that DLC coordinated with Zn atom via its SH or/and NH2 groups, thus inducing the sphalerite surface hydrophilic. The first-principle periodic calculation further demonstrated that DLC would prefer to be adsorbed on sphalerite (110) surface via its NH2 group because of the more negative adsorption energy of NH2 group complexed with unsaturated Zn atom. Overall, this study serves as a theoretical guidance for using DLC as an effective sphalerite depressant for the flotation separation of sphalerite from molybdenite.

Bromide Decorated Eco‐Friendly ZnSeTe/ZnSe/ZnS Quantum Dots for Efficient Blue Light‐Emitting Diodes

AbstractMulti‐shelled ZnSeTe/ZnSe/ZnS quantum dots (QDs) have served as a promising eco‐friendly emitter for blue quantum dot light‐emitting diodes (QLEDs). While extensive studies have concentrated on the optimization of the shell species and thickness of the multi‐shelled QDs to raise the QLED electroluminescent performance, very few reports focus on the QD surface states involving ligand and defect modulations which are essential for high‐performance QLEDs. Herein, the strategy of bromide decoration is theoretically and practically demonstrated to simultaneously diminish the QD surface defects by passivating the unsaturated Zn for strengthened carrier radiative recombination and removing the superabundant oleic acid through ligand exchange for efficient carrier transport. As a result, the merits of bromide decoration benefit a large increase in photoluminescence quantum yield (PLQY) from 39.7% to 86.2% at the wavelength of 443 nm, as well as a great enhancement of the device performance with over sevenfold improvement in external quantum efficiency (EQE) from 0.74% to 5.46% and a distinct decrease in turn‐on voltage from 6.7 to 5.9 V. Consequently, this work contributes an effective approach of the multi‐shelled QD surface decoration toward enhanced QLED performance.

Organic carboxylate-assisted engineering for fabricating Fe, N co-doped porous carbon interlinked carbon nanotubes towards boosting the oxygen reduction reaction for Zn-air batteries

Fe-Nx sites have been identified as core descriptors for Fe-N/C based oxygen reduction reaction catalysts. However, the low density and less utilization of Fe-Nx sites render these catalysts with inefficient catalytic performance. Herein, we develop an organic carboxylate-assisted engineering to construct Fe, N co-doped porous carbon interlinked carbon nanotubes (Fe/N-CCNTs) with high-density and sufficiently exposed Fe-Nx sites based on self-catalyzed effect. The existing forms of Fe include Fe-imidazole configuration and coordination with unsaturated Zn sites via organic carboxylate as linkers, leading to high-density Fe-Nx sites after pyrolysis. Besides, hexatomic carbon rings of organic carboxylate lower cyclization energy barrier for CNT formation, resulting in CNTs interlinked with separated active sites through “active point-conductive line-active point” connections. The optimal sample (Fe-BOAc-PNC) exhibits the onset potential of 0.93 V (vs. RHE) and half-wave potential of 0.84 V in alkaline solution. The liquid-state Zn-air battery (ZAB) employing Fe-BOAc-PNC generates large power density (160 mW/cm2) and stability over 160 h. Moreover, the assembled flexible ZAB displays superb power density of 93 mW/cm2 with robust flexibility. This work provides an insightful perspective for designing Fe-N/C catalysts with high-density and sufficiently exposed active sites for energy storage application.

Topologically Driven Pore/Surface Engineering in a Recyclable Microporous Metal-Organic Vessel Decorated with Hydrogen-Bond Acceptors for Solvent-Free Heterogeneous Catalysis.

The use of metal-organic frameworks (MOFs) comprising custom-designed linkers/ligands as efficient and recyclable heterogeneous catalysts is on the rise. However, the topologically driven bifunctional porous MOFs for showcasing a synergistic effect of two distinct activation pathways of substrates (e.g., involving hydrogen bonding and a Lewis acid) in multicomponent organic transformations are very challenging. In particular, the novelty of such studies lies in the proper pore and/or surface engineering in MOFs for bringing the substrates in close proximity to understand the mechanistic aspects at the molecular level. This work represents the topological design, solid-state structural characterization, and catalytic behavior of an oxadiazole tetracarboxylate-based microporous three-dimensional (3D) metal-organic framework (MOF), {[Zn2(oxdia)(4,4'-bpy)2]·8.5H2O}n (1), where the tetrapodal (4-connected) 5,5'-(1,3,4-oxadiazole-2,5-diyl)diisophthalate (oxdia4-), the tetrahedral metal vertex (Zn(II)), and a 2-connected pillar linker 4,4'-bipyridine (4,4'-bpy) are unique in their roles for the formation, stability, and function. As a proof of concept, the efficient utilization of both the oxadiazole moiety with an ability to provide H-bond acceptors and the coordinatively unsaturated Zn(II) centers in 1 is demonstrated for the catalytic process of the one-pot multicomponent Biginelli reaction under mild conditions and without a solvent. The key steps of substrate binding with the oxadiazole moiety are ascertained by a fluorescence experiment, demonstrating a decrease or increase in the emission intensity upon interaction with the substrates. Furthermore, the inherent polarizability of the oxadiazole moiety is exploited for CO2 capture and its size-selective chemical fixation to cyclic carbonates at room temperature and under solvent-free conditions. For both catalytic processes, the chemical stability, structural integrity, heterogeneity, versatility in terms of substrate scope, and mechanistic insights are discussed. Interestingly, the first catalytic process occurs on the surface, while the second reaction occurs inside the pore. This study opens new ways to catalyze different organic transformation reactions by utilizing this docking strategy to bring the multiple components close together by a microporous MOF.

The Facile Strategy of Improving the Long-Term Stability of Highly Transparent Polyvinyl Chloride by Introducing Unsaturated Zn Oleate and Uracil Derivatives.

In order to improve the initial color and the long-term heat stability of super-transparent polyvinyl chloride (PVC), a series of composite heat stabilizers consisting of unsaturated Zn oleate and uracil derivatives have been designed in this paper. The uracil derivatives are 1,3-dimethyl-6-amino-uracil (DAU) and 6,6′-diamino-1,1′,3,3′-tetramethyl-5,5′-(ethylidene)bisuracil (OSU). The static thermal stability, dynamic thermal stability, and transparency were used to evaluate the properties of the stabilized transparent PVC sheets. The results indicate that the compatibility between the stabilizer and PVC was greatly enhanced by introducing an unsaturated long-chain Zn oleate and a long alkyl chain bisuracil derivative. Through the thermal discoloration test, the best ratio of DAU/zinc oleate (DAU/Zn) and OSU/zinc oleate (OSU/Zn) was determined to be 4:1, with a total amount of 3 phr in 100 phr PVC. It was verified that the combination of zinc oleate with uracil derivatives could improve the long-term thermal stability of PVC, and the DAU/Zn was better than that of the OSU/Zn. In addition, through the transmission/haze verification, adding a proper amount of epoxidized soybean oil (ESBO) and phosphite ester to the OSU/Zn system has a certain synergistic effect. The thermal stability and transparency of PVC can be remarkably enhanced.

A LADH-like Zn-MOF as an efficient bifunctional catalyst for cyanosilylation of aldehydes and photocatalytic oxidative carbon–carbon coupling reaction

The rational design of component and coordination configuration of active center is critical and useful to the development of multifunctional MOF-based catalysts. Herein, a bifunctional Zn-MOF, Zn-ADBA, constructed by photoactive 4,4’-(9,10-anthracenediyl)dibenzoic acid (H2ADBA) ligand and Zn(II) ions, is employed as heterogeneous catalyst for efficient cyanosilylation and photocatalytic oxidative carbon–carbon coupling reactions. The unsaturated Zn(II) centers with strong Lewis acid character can effectively active aldehyde substates, which promotes Zn-ADBA to catalyze cyanosilylation of electron-withdrawing substituted benzaldehyde with a turnover frequency value up to 53.1 h−1. Meanwhile, the photo-functional ADBA2- ligands featuring large steric hindrance drive the Zn(II) center adopt the liver alcohol dehydrogenase (LADH) like characteristics, which renders Zn-ADBA (λmax absorption ​= ​406 ​nm) high-efficient photocatalytic oxidation of N-aryl-tetrahydroisoquinoline substrates with yields above 95% over 4 ​h under visible light. The recyclability of Zn-ADBA and the possible catalytic mechanisms are also systematically investigated by a series of experiments including PXRD, IR, EPR and DFT analyses.

High performance of ultrasonic-assisted synthesis of two spherical polymers for enantioselective catalysis

Chiral polymers have aroused great attention in among chiral supramolecular materials based on their features. Herein, for the first time, the synthesis of chiral polymeric composites (CMNPs/1,4-Zbtb & 1,3-Zbtb) have been reported with entrapment through three strategies: ultrasonic irradiation, solvothermal, and mechanical stirring. According to the obtained results, it is found that ultrasound-assisted synthesis can be considered as an inexpensive and efficient method than the others, from the point ofviewof energy and time consuming. In this strategy, encapsulation of chiral magnetic nanoparticles (CMNPs) by using tetrazole-based polymers (Zbtbs) happens, in-situly. These chiral sphere-like inorganic–organic polymers can be considered as core and shell composites with catalytic activity due to their acidic (semi unsaturated Zn: open metal sites) and basic (abundant basic nitrogens) centers. In these structures, the unprecedented chirality induction can happen from the core to shell by non-covalent interaction, easily. They could catalyze symmetric oxidation and asymmetric henry condensation to give chiral β-nitroalkanol. Circular dichroism and chiral gas chromatography were used to characterize the produced enantiomers. These chiral polymeric materials can be considered as unique acid-base bifunctional catalysts with efficient properties such as high stability, enantiomeric excess, enantioselectivity to the main product, and protecting from CMNPs leaching.

CO2 cycloaddition over ionic liquid immobilized hybrid zeolitic imidazolate frameworks: Effect of Lewis acid/base sites

Ionic liquid (IL) immobilized zeolitic imidazolate framework (ZIF) catalysts (IL-ZIF-8) were prepared through grafting IL on a dual-ligand ZIF by a facile post-synthetic modification. The coordinately unsaturated Zn as Lewis acid sites and bromide ions as Lewis base sites were confirmed in the resulted IL-ZIF. The density of Lewis acid/base sites was tuned easily by content of mixed linkers in the framework and/or the IL loadings. The coexistence of Lewis acid/base sites remarkably improved the activity for cycloaddition of CO2 with propylene oxide, compared with parent ZIFs and IL. In the absence of any co-catalyst and solvent, the prepared IL-ZIF-8(0.3) obtained a high yield of 97% with good stability and reusability. Besides, a Lewis acid/base synergistic catalytic mechanism was proposed. The synergetic interaction of Lewis acid sites and Lewis base sites significantly reduces energy barrier of propylene oxide ring-opening to 11.5 kcal mol−1 and thus promotes the CO2 cycloaddition reaction.

Tailoring the surface oxygen engineering of a carbon-quantum-dot-sensitized ZnO@H-ZnO1-x multijunction toward efficient charge dynamics and photoactivity enhancement

A well-steered coordination environment on photoelectrode can offer fruitful active sites and efficaciously alter atomic and electronic configuration to boost the performance in water oxidation. To enhance the performance of the photocatalytic oxygen-evolution reaction, enriched oxygenous-type carbon quantum dots (CQD) were combined with oxygen-deficient ZnO@H-ZnO1-x homojunctions for the first time. Specifically, hydrogenation created an unstoichiometric H-ZnO1-x surface through oxygen vacancies, which were responsible for the formation of coordinatively unsaturated Zn centers to drive the photoelectrochemical reaction by precise regulation of the charge density, valence-band edge, atomic geometric structure and electronic structure. The enriched photohole reservoir in carboxyl-conjugated CQD was a great benefit for super-rapid charge tunnels, thereby governing the rate of internal and interfacial charge separation and transport in the multijunction. Accordingly, the CQD/H-ZnO1-x/ZnO photoanodes showed a photoactivity enhanced five-fold relative to bare ZnO NR and maintained that high performance for 24 h of operation. Comprehensive analyses, involving electrochemical measurements, time-resolved photoluminescence, X-ray absorption spectra in situ and calculations with density-functional theory were undertaken to elucidate the underlying mechanism of enhancement and the route of directional charge transport as well as the interfacial charge dynamics over the CQD/H-ZnO1-x/ZnO photoelectrode. These findings provide a new track towards photoelectrodes that could yield not only strikingly enhanced photocatalysis but also satisfied stability for realistic application.

Unsaturated Zn–N2–O active sites derived from hydroxyl in graphene oxide and zinc atoms in core shell ZIF-8@ZIF-67 nanocomposites enhanced CO2 adsorption capacity

In order to form strengthened active sites for superior CO2 adsorption on core shell [email protected] nanocomposites, graphene oxide (GO) with oxygen-containing functional groups was used as support to synthesize hybrid adsorbents with unsaturated Zn–N2–O active sites. The results of XPS O 1s and FTIR analysis revealed that the Me–O functional group content in the 0.5 wt% graphene oxide (GO)-supported core shell [email protected] nanocomposite (38.9 at.%) was much higher than that in the 0.5 wt% reduced graphene oxide (RGO)-supported nanocomposite (19.4 at.%). This was because hydroxyl functional groups in the GO formed coordination bonds with zinc atoms in core shell [email protected] XPS N 1s spectra indicated that the incorporation of oxygen-containing functional groups in GO resulted in the transition of binding form from Me–N4 to Me–N2. The CO2 adsorption capacity of GO-supported core shell [email protected] gradually decreased from 2.15 to 1.30 mmol/g as GO weight percentage increased from 0.5 to 4 wt%, which was consistent with the decrease in BET surface area from 1378 to 585 m2/g and increase in peak pore diameter from 7.7 to 8.2 Å. Density functional theory (DFT) calculations demonstrated that unsaturated Zn–N2–O active sites in GO-supported core shell [email protected] nanocomposites resulted in a decreased OC⋯Zn interaction distance from 4.65 (Zn–N4 sites in core shell [email protected]) to 3.46 Å and an increased binding energy from 34.02 to 38.87 kJ/mol. Therefore, 0.5 wt% GO-supported core shell [email protected] nanocomposites exhibited the highest CO2 adsorption capacity of 2.15 mmol/g (at 273 K and 1 bar), 1.34 times higher than that of core-shell [email protected]

Enhanced Electrochemical Reduction of CO2 by Zeolitic Imidazolate Frameworks-8 Supported Silver Nanoparticles

Silver (Ag) is a typical catalyst for CO2 electroreduction. To improve the CO faradaic efficiency, ZIF-8 supported thiol-capped Ag nanoparticles (Ag NPs) of about 3.9 nm were facilely synthesized by reducing Ag + in ZIF-8 suspension in the presence of thiol-containing mercaptopropionic acid (MPA) molecules. MPA can induce the monodisperse Ag NPs formation, cap on the surface of Ag NPs and immobilize on ZIF-8 through coordinating with the unsaturated Zn 2+ cations. The Ag/ZIF-8 can efficiently reduce CO2 to CO with a maximum CO faradaic efficiency of 92.3% at the potential of −0.88 V (vs. RHE), higher than that of ZIF-8 and Ag/C. The performance improvement in CO2 electroreduction over Ag/ZIF-8 is probably attributed to the small-size of Ag NPs and the synergistic effect between Ag NPs and ZIF-8.

RETRACTED: Two Zn(II) coordination complexes: Gas separation property and treatment activity on chronic pulmonary interstitial disease and mechanism exploration

Abstract Two anion-directed Zn(II) coordination complexes of {[Zn2 (acc)1.5 (phen)2](NO3) (MeOH)5}n (1, H2acc = 4-carboxycinnamic acid, phen = 4-carboxycinnamic acid) and [Zn2 (acc) (phen)4](ClO4)2(H2O)8 (2) were synthesized and characterized via powder X-ray diffraction (PXRD) and single crystal X-ray diffraction and elemental analysis. Furthermore, the microporosities and the coordinately unsaturated Zn(II) sites enabled the activated complex 1 to reveal preemptive gas adsorption of CO2 and C2H2 instead of CH4. The high selectivity for C2H2 to CH4 was predicted on the basis of the calculations of IAST, which revealed the potential application of 1 in CH4/C2H2 selective isolation in the industry. Furthermore, the protective effect of complexes 1–2 on chronic pulmonary interstitial disease was evaluated. The chronic pulmonary interstitial disease animal model was established and complexes 1–2 were given for indicated treatment. The real time RT-PCR was carried out to determine the kgf7 gene relative expression level in the lung epithelial cells. To explore the mechanism, the ELISA detection kit was used for the measurement of the inflammatory cytokines IL-18 and TNF-α content.

High areal loading and long-life cycle stability of lithium-sulfur batteries achieved by a dual-function ZnS-modified separator

Stabilizing the lithium anode while inhibiting the shuttle effect to achieve stable circulation under high sulfur loading is an inevitable problem for the commercialization of lithium-sulfur batteries. A low cost of raw materials and a simple synthesis are also important prerequisites for product commercialization. In this paper, zinc sulfide (ZnS) nanoparticles embedded in nitrogen-doped 3D-carbon nanosheets (NCNS) are proposed as modified separator materials. During high-temperature carbonization of the carbon materials, a zinc sulphide phase transition occurs, resulting in an anion vacancy (S2-) and an unsaturated Zn centre. While maintaining catalytic activity, the unsaturated Zn centre in ZnS acts as a Lewis acid to form a coordinate bond with the polysulfide. Furthermore, a uniform distribution of N heteroatoms can effectively regulate Li+ flux through the separator, thereby achieving a stable cycle for the lithium anode. A cell with the ZnS/NCNS-modified separator can achieve a stable cycle at 0.5 C and superior electrochemical performance even with an areal sulfur loading of 6 mg cm−2. An excellent reduction in self-discharge was also confirmed by a 4% capacity attenuation after resting for 4 days. This work provides new insight on the design and preparation of novel separators for highly stable Li–S batteries via a “green” and cost-effective approach.

A Stable Zn-Based Metal–Organic Framework as an Efficient Catalyst for Carbon Dioxide Cycloaddition and Alcoholysis at Mild Conditions

Developing highly efficient heterogeneous catalysts for cycloaddition of CO2 and epoxides to produce cyclic carbonates is promising but challenging. In this work, a novel three-dimensional metal organic framework (MOF) with cylinder pore systems and unsaturated Zn sites has been demonstrated as potent candidate in CO2 fixation at mild and solvent-free conditions. The Zn(atz)(bdc)0.5, where atz = aminotriazole and H2bdc = terephthalic, exhibits microporous nature that can regulate the catalytic interaction of active centers and substrates. The structure stability has been systematically investigated and proven to be sufficient for practical application. Furthermore, the cooperative effects of porosity, CO2 binding affinity, activation centers, and synergism with co-catalyst have been deeply investigated. Moreover, high propylene epoxide conversion (97%) and selectivity (> 99%) have been achieved at mild conditions (60 °C and 1 MPa) with excellent cycle stability. Owing to the well-defined pore system, an obvious substrates selectivity has been clearly observed. A possible catalytic mechanism has been proposed and verified by DFT calculations. Furthermore, the prepared Zn-MOF can also be used as an efficient heterogeneous catalyst for the reaction of epoxides with alcohols to produce β-alkoxy alcohol.