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MOF-derived porous materials Co3O4 and Co/C with hierarchical structure (MHCo3O4 & Co/C) were prepared by the self-sacrificial template strategy, and the surface of such materials were functionally modified with 'polydopamine (PDA)' bionic membrane for entrapping horseradate peroxidase (HRP) in this work. MHCo3O4 was prepared in air atmosphere and Co/C was prepared in nitrogen atmosphere based on thermolysis of Co-MOF. The HRP@PDA@MHCo3O4 and HRP@PDA@Co/C could remain 96.8% and 93.7% catalytic activity compared to the free HRP, and exhibited better thermal stability and reusability. After 1 h incubation at 70 °C, the HRP@PDA@MHCo3O4 and HRP@PDA@Co/C retained 84.8% and 70.8% of the initial activity compared with less than 20% retained by free HRP; After 10 cycles, the HRP@PDA@MHCo3O4 and HRP@PDA@Co/C retained 92.4% and 85.4% of the initial activity. Moreover, the HRP@PDA@MHCo3O4 & Co/C exhibited extremely catalytic degradation efficient for 2,4-dichlorophenol in simulated wastewater, and 2 mmol·L-1 of 2,4-dichlorophenol was completely degraded within 15 min. The superior properties of HRP@PDA@MHCo3O4 & Co/C was researched by the analyses of kinetics and thermodynamics. The results suggested that the mass transfer resistance of the substrates were lower than that of the bulk solution, for the reason that the substrates were originally enriched on the hierarchical porous carrier close to enzyme. The specificity and binding affinity of the enzymatic reactors to substrates were enhanced by the functionalized 'PDA' bionic membrane on the carrier surface, compared with free enzyme in bulk buffer.

In this paper, the solid–liquid equilibrium of N-methylpyrrolidone (NMP) + MCl (M = Na, K, Rb, and Cs) + H2O ternary systems was investigated at three temperatures (T = 288.2, 298.2, and 308.2 K). ...

Metal-azolate-carboxylate frameworks have great potential for gas adsorption applications because azole ligands with a small size easily construct small pore MOFs with bare −N(H) donor sites. Howev...

Enzymes are efficient catalysts offering much more competitive processes than conventional chemical reactions. However, the lack of stability and reusability is a key issue on the use of enzymes in industrial applications. These drawbacks can generally be overcome by immobilization of the enzyme on a solid support. In this work, a Fe3O4/Fe-MOF core–shell with hierarchical pore sizes was prepared by growing Fe-MOF around Fe3O4 nanoparticles via solvothermal synthesis. Fe3O4/Fe-MOF integrates magnetic characteristics and hierarchical porous structure for supporting chloroperoxidase (CPO) or horseradish peroxidase (HRP). Immobilized CPO/HRP exhibited significantly enhanced stability against temperature stress and facilitated reuse. For example, HRP-Fe3O4/Fe-MOF can retain 94.1% activity after 10 reuses. Moreover, CPO/HRP-Fe3O4/Fe-MOFs were very efficient in the degradation of organic toxins, isoproturon or 2,4-dichlorophenol in simulated wastewater with a complete degradation within 15 min. The excellent performance of CPO/HRP-Fe3O4/Fe-MOF was investigated by kinetic and thermodynamic analysis. The results indicated that the diffusion resistance of substrates was reduced compared with that in a bulk solution because they were initially concentrated close to enzymes on the hierarchically porous support. The specificity and binding affinity of the immobilized enzymes are enhanced compared with the free enzymes.

Holey CoOOH nanosheets (CoOOH HNSs) are easily synthesized by a successive coordination–oxidation–hydrolysis strategy. The CoOOH HNSs possess a large surface area, numerous pores, and substantial edge atoms with excellent electroactivity towards the oxygen evolution reaction in alkaline solution. The overpotential of 305 mV at 10 mA cm−2 for the CoOOH HNSs exceeds that of most monometallic Co-based electrocatalysts.

Both methane (CH4) and acetylene (C2H2) are important energy source and raw chemicals in many industrial processes. The development of an energy-efficient and environmentally friendly separation and purification strategy for CH4 and C2H2 is necessary. Ultramicroporous metal-organic framework (MOF) materials have shown great success in the separation and purification of small-molecule gases. Herein, the synergy effect of tritopic polytetrazolate and ditopic terephthalate ligands successfully generates a series of isoreticular ultramicroporous cadmium tetrazolate-carboxylate MOF materials (SNNU-13-16) with excellent CH4 and C2H2 purification performance. Except for the uncoordinated tetrazolate N atoms serving as Lewis base sites, the pore size and pore surface of MOFs are systematically engineered by regulating dicarboxylic acid ligands varying from OH-BDC (SNNU-13) to Br-BDC (SNNU-14) to NH2-BDC (SNNU-15) to 1,4-NDC (SNNU-16). Benefiting from the ultramicroporous character (3.8-5.9 A), rich Lewis base N sites, and tunable pore environments, all of these ultramicroporous MOFs exhibit a prominent separation capacity for carbon dioxide (CO2) or C2 hydrocarbons from CH4 and C2H2. Remarkably, SNNU-16 built by 1,4-NDC shows the highest ideal adsorbed solution theory CO2/CH4, ethylene (C2H4)/CH4, and C2H2/CH4 separation selectivity values, which are higher than those of most famous MOFs with or without open metal sites. Dynamic breakthrough experiments show that SNNU-16 can also efficiently separate the C2H2/CO2 mixtures with a gas flow rate of 4 mL min-1 under 1 bar and 298 K. The breakthrough time (18 min g-1) surpasses most best-gas-separation MOFs and nearly all other metal azolate-carboxylate MOF materials under the same conditions. The above prominently CH4 and C2H2 purification abilities of SNNU-13-16 materials were further confirmed by the Grand Canonical Monte Carlo (GCMC) simulations.

The construction of nanocage-based metal-organic frameworks (MOFs) with both open metal sties (OMSs) and optimal pore spaces may offer a powerful route for high-performance gas storage and purifica...

The construction of superstable metal-organic frameworks (MOFs) for selective gas uptake is urgently demanded but remains a great challenge. Herein, a unique bifunctional deformed [Ga3O(COO)6] inorganic secondary building unit (SBU) generated from the desymmetrical evolution of typical triangular prismatic trinuclear cluster was first introduced, which was extended by an isosceles triangular organic linker to produce a robust Ga-MOF (SNNU-63). Remarkably, SNNU-63 can stabilize in water at 25 °C for 96 h and at 80 °C for more than 24 h, which surpasses nearly all other Ga-MOFs. The combined effects of open metal sites and hydrophobic pore environment provided by deformed [Ga3O] SBUs render SNNU-63 with high C2H2 storage capacity and efficient C2H2 and natural gas purification performance. The ideal adsorbed solution theory calculation, column breakthrough tests, and grand canonical Monte Carlo simulations demonstrate that SNNU-63 is a potential material for addressing the challenge of C2H2/CO2 and C2H2/CH4 mixture separation under ambient conditions.

The separation of a mixture of C2H2 and CO2 is a great challenge due to their similar molecular sizes and shapes. Al-based metal-organic frameworks (Al-MOFs) have great promise for gas separation applications due to their light weight, high stability, and low cost. However, the cultivation of suitable Al-MOF single crystals is extremely difficult and has limited their explorations up to now. Since In, Ga, and Al are all 3p-block metal elements, a systematic application of the periodic law to investigate 3p-MOFs will undoubtedly help in the understanding and development of worthy Al-MOF materials. Herein, we report the design of a robust 3p metal-organic framework platform (SNNU-150) and the systematic regulation of C2H2/CO2 separation by open 3p-block metal sites. X-ray single-crystal diffraction analysis reveals that SNNU-150 is a 3,6-connected 3D framework consisting of [M3O(COO)6] trinuclear secondary building units (SBUs) and tritopic nitrilotribenzoate (NTB) linkers. Small {[M3O(COO)6]4(NTB)6} tetrahedral cages and extra-large {[M3O(COO)6]10(NTB)14} polyhedral cages connect with each other to generate a hierarchically porous architecture. These 3p-MOFs present very high water, thermal, and chemical stability, especially for SNNU-150-Al, which can maintain its framework at 85 °C in water for 24 h and in a room-temperature environment for more than 30 days. IAST calculations, breakthrough experiments, and GCMC simulations all show that SNNU-150 MOFs have top-level C2H2/CO2 separation performance and follow the order Al-MOF > Ga-MOF > In-MOF.

In this work, manganese oxide with a 3 × 3 tunnel structure was synthesized. Mg-todorokite was treated with HNO3 to obtain H-todorokite, which was used as an electrode for adsorption of Cs+ from aqueous solution by an electrochemical reaction. H-todorokite was electrochemically reduced to lower oxidation state to enhance its negative charge and simultaneously increase the amount of cations because of the charge compensation. The Cs+ adsorption on H-todorokite was completed by a coupled electrochemical reaction (the redox reaction between Mn3+ and Mn4+) and an ion-exchange reaction between Cs+ and H+ ions. Cyclic voltammetry measurements at different pHs and Cs+ concentrations were performed. H-todorokite revealed high electrochemical adsorption capacity for Cs+ because of the high crystallinity and stability of the materials, which reached 6.0 mmol g–1 in 0.1 mol·L–1 Na2SO4 solution.

Metal-organic frameworks (MOFs) with large surface area, abundant coordination metal centers and tunable structures are regarded as promising electrocatalysts for the water splitting reaction. However, the less accessible active sites and poor stability of MOFs hinder their potential practical applications. Hierarchical double-layer hydroxide (LDH)/MOF electrocatalysts that combine the advantages of two materials are expected to overcome these drawbacks. Herein, we develop a simple and universal strategy, in situ pseudomorphic transformation, to construct hierarchical LDH/MOF electrocatalysts. Accordingly, ultra-thin Fe-Ni LDH nanosheets are in situ produced in the heterometallic MOF during the transformation process. Profiting from the abundant metal sites and the extended electron transport channel from the inserted ultra-thin LDH arrays, the hierarchical Fe-Ni LDH/MOFs exhibit striking electrochemical activities for the oxygen evolution reaction (OER). In particular, the as-synthesized Fe-Ni LDH/MOF-b2 delivers the best OER performance, exhibiting an ultralow overpotential (255 mV at 10 mA cm-2), minimum Tafel slope (24 mV dec-1) and outstanding cycling durability. Meanwhile, the evolution process of the hierarchical Fe-Ni LDH/MOF has been monitored with the controllable in situ semi-transformation strategy. This also provides an opportunity to decipher the original active species for the OER process. Mechanism analysis indicates that the bimetallic MOF and bimetallic LDH are both active species, and the excellent OER performance of hierarchical Fe-Ni LDH/MOF could be attributed to the effect of "a whole greater than the sum of the parts".

It is well-known that the formation of ferroalloy with the addition of the second or third metal during the steel-making process usually can improve the performance of the iron. Inspired by ferroalloy materials, it is speculated that the pore environment, framework charge, and catalytic properties of metal-organic frameworks (MOFs) could be optimized dramatically via the introduction of ferroalloy-like inorganic building blocks. However, different to ferroalloy, the accurate integration of different metals into one MOF platform is still challenging. Herein, taking advantages of the good compatibility for metals in trigonal prismatic trinuclear cluster, a series of Fe-based alloy-like [M3O(O2C)6] motifs (M3 = Fe3, Fe1.5Ni1.5, Fe1.5Co1.5, Fe1.5Ti1.5, FeCoNi, and FeTiCo) are successfully generated, which further lead to a robust Fe-MOF material family (SNNU-5s). These multicomponent MOFs not only provide a good chance to explore the impact of pore environment on gas adsorption/separation but also offer an opportunity to the efficient electrocatalytic reaction directly. Accordingly, compared with the SNNU-5-Fe parent structure, the pore characters of heterometallic SNNU-5 MOFs are clearly regulated by the type of alloy-like building blocks. SNNU-5-FeTi displays more superior gas separation performance for CO2/CH4, C2H2/CH4, C2H4/CH4, and C2H2/CO2 gas mixtures. What is more, benefited from the multimetallic active sites and their catalytic synergy, FeCoNi-ternary alloy-like cluster-based SNNU-5 MOF material exhibits an exceptional oxygen evolution reaction activity in aqueous solution at pH = 13, which delivers a low overpotential (ηj=10 = 317 mV), a fast reaction kinetics (Tafel slope = 37 mV dec-1), and excellent catalytic stability. This facile multialloy-like building block strategy holds promise to accurately design and improve the performance of MOFs, as well as open an avenue to understand the related mechanisms.

High-quality CoP nanorings (CoP NRs) are easily achieved using a phosphorating treatment of CoOOH nanorings, and reveal high activity towards the hydrogen evolution reaction and the nitrate electrocatalytic reduction reaction due to substantial coordinately unsaturated active sites, a high surface area, and available mass transfer pathways. Consequently, the CoP NRs can achieve a faradaic efficiency of 97.1% towards NO3−-to-NH3 conversion and provide an NH3 yield of 30.1 mg h−1 mg−1cat at a −0.5 V potential.

Evaluating the effect of ligand substitution on metal ions and/or clusters during the MOF growth process is conducive to rational design of isoreticular MOFs with improved performance. Through topo...

The Solubility, density and refractive index of the formamide(FA)/N-methylformamide(NMF)/N,N-dimethylformamide(DMF) + rubidim bromide/cesium bromide+ water ternary systems were determined at (283.15, 298.15 and 313.15) K. The solubility of the RbBr and CsBr decrease significantly when adding amides into the aqueous solution. The variation trend of density is consistent with solubility, and the change of the refractive index is different. The isothermal experimental solubility was correlated by the NRTL model and the UNIQUAC model. The isothermal solubility, density and refractive index of the ternary systems were fitted by the four parameter equation. Moreover, the mean activity coefficients of the FA/NMF/DMF + RbBr/CsBr + H2O systems at experimental temperatures were obtained through the UNIQUAC model. Besides, to investigate the temperature effect on the solid-liquid equilibrium, the multiple temperatures solubility was fitted by the modified Apelbl at equation and the λh equation.

A multitude of industrial processes are catalyzed by two or more enzymes working together in a cascade way. However, designing efficient enzymatic cascade reactions is still a challenge. In this work, a TiO2 thin film with mesoporous pores was prepared and used as carrier for co-immobilization of chloroperoxidase (CPO) and glucose peroxidase (GOx). By adjusting the dosage of hexadecyltrimethylammonium bromide (CTAB) and the ratio of the two enzymes, CPO and GOx were well distributed and positional orientated to their own appropriate pores to form an ordered “occupation” based on a “feet in right shoes” effect. Moreover, when the pore size was controlled around 12 nm, the enzymes aggregation was inhibited so as to avoid the decrease of activity of enzyme; The catalytic performance of TiO2–GOx and CPO composites was evaluated by the application of decolorization of Orange G dye in a cascaded manner. The oxidant H2O2 needed by CPO is generated in situ through glucose oxidation by GOx. Upon co-immobilization of CPO and GOx on the same carrier, a large increase in the initial catalytic efficiency was detected when compared to an equimolar mixture of the free enzymes, which was four times greater. Moreover, the affinity of the enzyme toward substrate binding was improved according to the kinetic assay. The thermal stability of TiO2–GOx and CPO composites were greatly improved than free enzymes. The TiO2–GOx and CPO composites can be easily separated from the reaction media which facilitate its recycle use.

The concept of high-performance excited-state intramolecular proton transfer (ESIPT)-based fluorescent metal–organic framework (MOF) probes for Al3+ is proposed in this work. By regulating the hydroxyl groups on the organic linker step by step, new fluorescent magnesium–organic framework (Mg–MOF) probes for Al3+ ions were established based on the ESIPT fluorescence mechanism. It is observed for the first time that the number of intramolecular hydrogen bonds between adjacent hydroxyl and carboxyl groups can effectively adjust the ESIPT process and lead to tunable fluorescence sensing performance. Together with the well-designed porous and anionic framework, the Mg–TPP–DHBDC probe decorating with a pair of intramolecular hydrogen bonds exhibits extra-high quantitative fluorescence response to Al3+ through an unusual turn-off (0–1.2 μM) and turn-on (4.2–15 μM) luminescence sensing mechanism. Notably, the 28 nM limit of detection value represents the lowest record among all reported MOF-based Al3+ fluorescent...

Although chloroperoxidase (CPO) has long been recognized as a powerful and versatile catalyst, its applications have been thwarted by the difficulty in regenerating the active enzyme and substrate (peroxide) induced protein inactivation. In this paper, we describe the fabrication and characterization of chloroperoxidase (CPO) and glucose oxidase (GOx) on the surface of MGO. The performance of the immobilized CPO was considerably enhanced by coupling with GOx that provided the required H2O2 in situ through glucose oxidation. The activity of MGO-GOx-CPO (96.6%) towards the decolorization of orange G was much superior to that of MGO-GOx+MGO-CPO (86.2%), probably as a result of reduced mass transfer resistance between CPO and H2O2 generated from GOx molecules. Interestingly, MGO-GOx-CPO reached its peak activity (95.2%) when temperature was maintained between 42 °C and 50 °C compared to the optimal temperature of 35 °C for the free enzyme, possibly due to dispersion of the otherwise stacked MGO below 42 °C. Finally, MGO-GOx-CPO can be conveniently reused for its ease of recovery in the presence of an external magnetic field, with ∼38.5% activity remained after 6 cycles of applications. This work demonstrates the feasibility of co-immobilizing CPO and GOx onto MGO and the potential of MGO-GOx-CPO in environmental applications.

In this paper, the phase behavior of the systems composed of [Cnmim]Cl/Br (n = 2, 4, 6, 8), Rb2SO4/Cs2SO4 and H2O was investigated at 298.2 K and 308.2 K. Some systems were solid – liquid equilibrium and some were liquid – liquid equilibrium because of the effect of the inorganic salts and the cation and anion of the ionic liquids. For solid – liquid equilibrium systems, the solubility, density and refractive index of the saturated solution were determined. For liquid – liquid equilibrium systems, the binodal curves were measured. The experimental solubility, density and refractive index were fitted using an empirical equation. The binodal curves data of liquid – liquid equilibrium systems were correlated using Merchuk equation. Moreover, the effect of inorganic salts, ionic liquids, and temperature on the phase behavior of the studied systems was discussed in detail.

The controllable synthesis of highly stable porous metal–organic frameworks (MOFs) with targeted functions is urgently needed but still challenging up to now. In this work, we report the latest achievement in our continuous quest for robust 9-connected (9-c) MOFs based on [M3(O/OH)(COO)6(pyridine)3] building blocks. Different from the reported nets (ncb, xmz and pacs-MOFs) constructed from integrated or separated carboxylate and pyridine ligands, our metal–organic linker (MOL) strategy led to the discovery of six fascinating 9-c MOFs (SNNU-51–56) showing two types of completely new topological nets generated by cis, trans-coordination isomerism. As expected from highly connected architectures and the absence of open metal sites, all these MOFs show high thermal and moisture stability. They can even retain their frameworks after being treated at different pH values for 24 h. Furthermore, SNNU-51–56 not only inherit the excellent gas uptake performance of robust 9-c MOFs, but also exhibit extremely high CH4 separation from CO2, C2H2 and C2H4. Together with robust frameworks, the effective inner-cluster redox process in [M3(OH)(COO)6(pyridine)3] (M = Fe, Co and Ni) units makes SNNU-51–56 high-performance electrochemical pseudocapacitor materials. The asymmetric supercapacitor (ASC) fabricated with the SNNU-52 positive electrode and activated carbon (AC) negative electrode can be reversibly charged/discharged in a working voltage range of 0–1.6 V in 2 M KOH aqueous electrolyte for application in practical energy storage devices, and two serially connected ASCs can continuously light a light emitting diode. In all, greater control over the MOF structure, excellent thermal and chemical stability, and superb metal compatibility make [M3(O/OH)(COO)6(pyridine)3] clusters an ideal building block to design multifunctional MOF materials in the future.

The design and synthesis of highly stable metal–organic framework (MOF) materials are urgently needed but are still challenging. Demonstrated herein is a superstable 3p-block metal–organic framework platform (3p-MOFs, SNNU-5-Al, Ga and In) inspired by the periodic law of elements. Apart from extra-high thermal stability (up to 500 °C), SNNU-5-Al shows excellent water tolerance (24 days at RT and 1 day at 80 °C in pure water) and prominent pH stability (4 to 12). Superlarge cuboctahedral and octahedral cages in SNNU-5s lead to excellent CO2 and C1/C2-hydrocarbon uptake and separation performance as well as excellent methane storage capacity under 65 bar pressure (345 cm3 g−1 at 273 K and 279 cm3 g−1 at 298 K for SNNU-5-Al). The strong Lewis acid nature of open 3p metal sites further makes SNNU-5 MOFs ideal heterogeneous catalysts for CO2 catalytic fixation with epoxides. Overall, this work provided a significant advance in the development of robust functional MOF materials for energy and environmental applications.

In the present work, the density, ρ , refractive index, n D, and dynamic viscosity, η , for four binary solutions containing ionic liquids [C n mim]Br (C n mim=1-alkyl-3-methylimidazolium, n =6, 8) and 1,2-propanediol (PG)/1-propanol (NPA), at temperatures 288.15– 333.15 K and ambient pressure were investigated. Additionally, the excess molar volume, V mE, and the refractive index deviations, Δ n D, were calculated and correlated using the Redlich-Kister polynomial equation. The density, refractive index, and natural logarithm of dynamic viscosity of the binary mixtures were correlated using empirical equation. The influence of alcohol, ionic liquids, and temperature on the physicochemical properties was discussed.

The high storage capacity versus high selectivity trade-off barrier presents a daunting challenge to practical application as an acetylene (C2 H2 ) adsorbent. A structure-performance relationship screening for sixty-two high-performance metal-organic framework adsorbents reveals that a moderate pore size distribution around 5.0-7.5 A is critical to fulfill this task. A precise pore space partition approach was involved to partition 1D hexagonal channels of typical MIL-88 architecture into finite segments with pore sizes varying from 4.5 A (SNNU-26) to 6.4 A (SNNU-27), 7.1 A (SNNU-28), and 8.1 A (SNNU-29). Coupled with bare tetrazole N sites (6 or 12 bare N sites within one cage) as high-density H-bonding acceptors for C2 H2 , the target MOFs offer a good combination of high C2 H2 /CO2 adsorption selectivity and high C2 H2 uptake capacity in addition to good stability. The optimized SNNU-27-Fe material demonstrates a C2 H2 uptake of 182.4 cm3 g-1 and an extraordinary C2 H2 /CO2 dynamic breakthrough time up to 91 min g-1 under ambient conditions.

High gas‐uptake capacity is desirable for many reasons such as gas storage and sequestration. Moreover, ultrahigh capacity can enable a practical separation process by mitigating the selectivity factor that sometimes compromises separation efficiency. Herein, a single‐walled nickel–organic framework with an exceptionally high gas capture capability is reported. For example, C2H4 and C2H6 uptake capacities are at record‐setting levels of 224 and 289 cm3 g−1 at 273 K and 1 bar (169 and 110 cm3 g−1 at 298 K and 1 bar), respectively. Such ultrahigh capacities for both gases give rise to an excellent separation performance, as shown for C2H6/C2H4 with breakthrough times of 100, 60 and 30 min at 273, 283 and 298 K and under 1 atm. This new material is also shown to readily remove ethylene released from fruits, and once again, its ultrahigh capacity plays a key role in the extraordinary length of time achieved in the preservation of the fruit freshness., Long live bananas! A stable nickel metal–organic framework with a voracious and unsurpassed appetite for ethane can also perform direct air capture of ethylene to keep bananas going on and on.

Halloysite nanotube (HNT) is a natural bio-compatible and stable nanomaterial available in abundance at low-cost. In this work, HNT was modified by two strategies to make it suitable for supporting immobilization of chloroperoxidase (CPO). Firstly, Fe3O4 nanoparticles were deposited on HNT, so magnetic separation can be used instead of centrifugation. Then, the magnetic HNT was modified by 3-aminopropyltriethoxysilane (APTES), which can provide amine group on surface of HNT and meanwhile inhibit the agglomeration of magnetic HNT. Then, HNT-Fe3O4 -APTES was linked with branched polyethyleneimine (PEI) to provide more amino for binding with enzyme. The so-prepared CPO@HNT-Fe3O4-APTES-PEI showed enhanced enzyme loading, reusability, improved thermal stability and tolerance to organic solvents than free CPO. For example, after 10 repeated uses, CPO@HNT- Fe3O4-APTES-PEI can maintain 92.20% of its original activity compared with 65.12% of activity of CPO@HNT-APTES-PEI and 45.69% of activity of CPO@HNT. The kinetic parameters indicated the affinity and specificity of immobilized enzyme to substrate was increased. CPO@HNT-Fe3O4-APTES-PEI was very efficient when it was applied in the degradation of pesticides mesotrione in wastewater. The degradation efficiency can reach 90% within 20 min at range of 5–40 μmol·L−1. These results ensure the potential practical application of this bio-materials in wastewater treatment.

Halloysite nanotubes (HNT) is a kind of kaolin clay consisting of one alumina octahedron sheet and one silica tetrahedron sheet formed by rolling flat sheets into a hollow tubular structure. It is an ideal carrier for immobilization of enzyme due to its large surface area, biocompatibility, and chemical and mechanical stability besides abundance and low-cost. In order to make the most of this carrier for enzyme immobilization, in this work, two strategies were proposed for entrapping and embedding chloroperoxidase (CPO) on both inner/outer wall of HNT rather than in the hollow space alone by pH modulated electrostatic adsorption. Besides the enhanced loading amount, the thermal stability and tolerance to organic solvents of immobilized CPO (I-CPO) was greatly improved compared to the free enzyme. The free CPO can retain only 11.66% activity after 1 h incubation at 80 °C, while the I-CPO remained 87.63% activity at the same condition. Even after 1.5 h incubation at 90 °C, when the free CPO lost all its activity, the I-CPO can still remain 40.3% activity; Moreover, in the presence of organic solvent (ethyl acetate, acetonitrile, methanol, and DMF) with volume fraction of 10%, almost no loss of activity of I-CPO was observed, but free CPO can only remain 41.6%, 38.2%, and 23.5% of its initial activity in ethyl acetate, acetonitrile, methanol-water mixed system respectively, and even inactivated completely in DMF in the same condition. Furthermore, the enzymatic kinetic parameters (Km, and kcat/Km) suggested the affinity and specificity of I-CPO to the substrate was improved. I-CPO was very efficient when applied in the degradation of isoproturon in wastewater. The isoproturon with initial concentration of 26.7 μmol·L−1 can be completely degraded only in 10 min, indicating a potential practical application of I-CPO in treatment of wastewater containing pesticide.

CsF + CsBr + H2O and CsF + CsNO3 + H2O mixed-electrolyte systems were investigated by the potentiometric method. The experimental data were modeled by connecting the Nernst equation with the Pitzer...

Metal–organic frameworks have shown promising applications as electrode materials for supercapacitors because of the high porosity and tunable structures, but their poor water stability and conductivity limit their capacitance and efficiency. To demonstrate how to overcome these drawbacks, three isostructural Ni–organic frameworks with [NiII2NiIII(μ3-OH)(COO)6] trinuclear building blocks are selected. Taking advantage of high-connected architectures, absence of open metal sites, and effective inner-cluster redox process, three Ni–organic frameworks all are stable in KOH electrolyte and exhibit a pseudo-capacitor behavior with high specific capacitances up to 394, 426, and 465 F g–1. The increasing porosity facilitates the diffusion of metal ions and electrons and thus increases their electrochemical performance. Furthermore, we demonstrate that the in situ fabrication of metal–organic frameworks with graphene oxide can effectively promote their supercapacitor performance. With a given 3% graphene oxide do...

An enzyme–TiO2 composite with high catalytic activity, stability at harsh reaction condition, and good reusability was prepared via modification of TiO2 by polydopamine (PDA) to tethering with chloroperoxidase (CPO) or horseradish peroxidase (HRP) through glutaraldehyde. TiO2 played both roles of solid carrier and photo-catalyst in the application of soluble dyes decolorization, and in this way, the loss of enzymatic activity during enzyme immobilization can be compensated. Because the enzyme and TiO2 were included in same composites, an enzyme-photo bifunctional synergistic catalysis was observed due to the interaction between enzyme and TiO2, resulting in that the formation of catalytic intermidiate, OH, increased and the band gap energy of TiO2 became narrow. The light absorption by TiO2 was extended from the UV region to the visible region through coated by PDA and CPO/HRP so as that CPO/HRP-TiO2@PDA can be used under visible light irradiation instead of ultraviolet light irradiation, which can avoid the decrease of enzyme activity by ultraviolet light irradiation. HRP-TiO2@PDA composite had even the best resuability of enzyme immobilized on solid support compared with the data in reference, in our best knowledge. There was no activity loss of HRP-TiO2@PDA after 15 times use, and more than 90% activity can be remained after 25 times use. Even after 40 times use, the relative activity of HRP-TiO2@PDA was 63.6% of that in the first run. The difference of reusability between CPO and HRP have relationship with the distribution of function group among the surface of enzyme molecule.

CPO, a versatile enzyme, has limitations in industrial applications due to its poor stability and the difficulty of reuse. The preparation of stable immobilized enzymes with high catalytic activity is therefore desirable, but remains a challenge. A facile preparation of a series of enzyme-inorganic hybrid micro-spheres [chloroperoxidase (CPO)-(Cu/Co/Cd)3(PO4)2] and its application in the decolorization of crystal violet is reported in this work. All the hybrid micro-spheres show a multilayer petal-like structure. The formation of hybrid micro-spheres were proposed via four stages: crystallization, in-situ coordination, self-assembly and size growth. The process was entropy-driven, and there was a competition between precipitation of phosphate and coordination of M2+ with amide groups of CPO. The introduction of excess of chloride ions retarded the phosphate from precipitating by forming [MCl4]2− complexes, while simultaneously promoting the coordination of M2+ with amide groups. These hybrid materials showed high bio-catalytic activity in the decolorization of crystal violet. The decolorization efficiency reached 99.66%, 98.44% and 98.05% just within 3 min using CPO-Cu3(PO4)2, CPO-Cd3(PO4)2 and CPO-Co3(PO4)2 respectively. They also have good thermal stability, and can keep 52.89% catalytic activity after 8 cycles of use. CPO-inorganic hybrid micro-spheres [chloroperoxidase (CPO)-(Cu/Co/Cd)3(PO4)2] is promising in the treatment of waste water containing crystal violet. It also has potential application for treatment of other soluble organic dyes in industrial wastewater.

Functionalization by amine groups has been recognized as an effective route to promote the gas capture and separation performance of MOF materials; however, it remains elusive to date what is the optimal number of functional amine groups and which specific MOFs are suitable to be functionalized. To answer these questions, systemic investigations on the interactions between gas molecules and NH2-functionalized MOFs are necessary. Here a microporous Zn-F-triazolate framework which can be easily decorated by different −NH2 groups is selected (Zn-F-TRZ, Zn-F-ATRZ, and Zn-F-DATRZ; TRZ = 1,2,4-triazole, ATRZ = 3-amino-1,2,4-triazole, DATRZ = 3,5-diamino-1,2,4-triazole) to discuss the effect of amine groups on CO2 and C1/C2 hydrocarbon capture and separation. When the pressure is lower than about 0.15 atm, the CO2 uptakes increase directly with the number of anime groups (Zn-F-TRZ < Zn-F-ATRZ < Zn-F-DATRZ). However, at 1 atm, the decoration of one amine group effectively improves the CO2 adsorption of the Zn-F-t...

The development of efficient catalysts with high activity and selectivity for the direct synthesis of H2O2 from H2 and O2 is highly desirable yet challenging. Herein, a series of Pd–Sn bimetallic nanocrystals with hollow structure have been successfully created as highly active and selective catalysts for direct H2O2 synthesis. We found that the introduction of Sn played an important role on the morphology evolution and composition control of the hollow Pd–Sn nanocrystals. Significantly, after rapid thermal treatment, the obtained hollow Pd–Sn/TiO2 catalysts can deliver complete inhibition of H2O2 decomposition/hydrogenation, resulting in a large activity enhancement for the H2O2 production. The H2 selectivity could be further improved by using water as the reaction solvent. Further investigation showed that the large activity enhancement of hollow Pd–Sn/TiO2 catalysts for the direct H2O2 synthesis can be attributed to the presence of PdO, the ensemble effect between the Pd and Sn, and the interface effec...

Bimetallic noble metal nanocrystals have been widely applied in many fields, which generally are synthesized by the wet-chemistry reduction method. This work presents a purposely designed atoms diffusion induced phase engineering of PtAu alloy nanocrystals on platy Au substrate (PtAu-on-Au nanostructures) through simple hydrothermal treatment. Benefitting from the synergistic effects of component and structure, PtAu-on-Au nanostructures remarkably enhance the dehydrogenation pathway of the formic acid oxidation reaction (FAOR), and thus exhibit much higher FAOR activity and durability compared with Pt nanocrystals on platy Au substrate (Pt-on-Au nanostructures) and commercial Pd black due to an excellent stability of platy Au substrate and a high oxidation resistance of PtAu alloy nanocrystals. The atoms diffusion-induced phase engineering demonstrated in this work builds a bridge between the traditional metallurgy and modern nanotechnologies, which also provides some useful insights in developing noble metals based alloyed nanostructures for the energy and environmental applications.

Phase behavior and extraction ability of aqueous two-phase systems(ATPs) consisting of ionic liquids(ILs), Cs2CO3 and water were investigated in this paper. Four kinds of ionic liquids, namely, 1-amyl-3-methylimidazolium bromide([C5mim]Br), 1-hexyl-3-methylimidazolium bromide([C6mim]Br), 1-heptyl-3-methylimidazolium bromide ([C7mim]Br) and 1-octyl-3-methylimidazolium bromide([C8mim]Br), were examined to discuss the influence of alkyl groups. Binodal curves and tie-lines at 288.15, 298.15 and 308.15 K were obtained. The partitioning behavior for L-tryptophan in such ATPs was further investigated. The effect of temperature, pH, Cs2CO3 concentration and the structure of ionic liquids on the partitioning were discussed in detail.

A porous MOF platform (SNNU-65s) formed by creatively combining paddle-wheel-like [Cu2(COO)4] and trigonal prismatic [M3(μ3-O)(COO)6] building blocks was designed herein. The mixed and high-density open metal sites and the OH-functionalized pore surface promote SNNU-65s to exhibit ultra-high C2H2 uptake and separation performance. Impressively, SNNU-65-Cu-Ga stands out for the highest C2H2/CO2 (18.7) and C2H2/CH4 (120.6) selectivity among all the reported MOFs at room temperature.