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Новости Nature

Graphene nanoplatelets as nanofillers in mesoporous silicon oxycarbide polymer derived ceramics

Cooperative adsorption of carbon disulfide in diamine-appended metal–organic frameworks

Metal-organic framework glasses with permanent accessible porosity

A robust zirconium amino acid metal-organic framework for proton conduction

Metal-induced ordered microporous polymers for fabricating large-area gas separation membranes

Author Correction: Natural gas upgrading using a fluorinated MOF with tuned H2S and CO2 adsorption selectivity

Continuous negative-to-positive tuning of thermal expansion achieved by controlled gas sorption in porous coordination frameworks

Ordered polymeric membranes using metals

Hierarchical Flowerlike 3D nanostructure of Co3O4@MnO2/N-doped Graphene oxide (NGO) hybrid composite for a high-performance supercapacitor

Porous hierarchy

Molecular sieving of ethylene from ethane using a rigid metal–organic framework

An efficient nanosieve

Лента новостей (Journal of Porous Materials)

Preparation of ordered meso/macroporous HPW/titania–silica catalyst for efficient oxidative desulfurization of model fuel

Abstract

In this study, ordered meso-macroporous titania–silica–polyoxometalate (HPW/SiO2–TiO2) material was prepared in one-pot by evaporation-induced self-assembly (EISA) method, with non-ionic surfactant (P123) and monodisperse polystyrene microspheres applied as co-structure-directing agents. And the oxidative desulfurization (ODS) application of as-synthesized hierarchical nanocomposite materials was tested in model fuel. The characterization results of catalyst suggested that Keggin-type polyoxometalate was successfully incorporated into the ordered meso-macroporous SiO2–TiO2 framework. Moreover, the effect of Lewis acid center of the HPW/SiO2–TiO2 catalyst on ODS process was investigated. The optimum proportion of titanium and silicon ratio on catalyst was found to be 1:1, which exhibited remarkable catalytic performance on aromatic sulfur compounds at mild conditions. It revealed that Lewis acid sites played an important role in selectively adsorb DBT and its derivatives. What’s More, the combination of Lewis acid sites and ordered meso/macroporous architecture of catalyst will further facilitated the mass transport in ODS process. No decrease in the activity was observed after six runs, indicating a good stability of as-prepared catalyst.

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A comparative study on mesocellular foam silica with different template removal methods and their effects on enzyme immobilization

Abstract

Mesocellular foam silica (MCF) was synthesized using Pluronic P-123 triblock copolymer as a template. Calcination and solvent extraction were employed to remove templates and compared. Through physical, chemical and functional characterization interesting results have been observed. Microstructures of the two MCFs were very different. Pore structure of the calcined MCF was found to be more ordered than that of the solvent extracted MCF. However, pores of the solvent extracted MCF seemed more defined and spongy under SEM observations. Surface functional groups and their concentrations characterized by ToF-SIMS were also found to be different. Surface silanol groups were found to be more concentrated in the calcined MCF. Each type of MCFs was subsequently grafted by an amine functional group, adsorbed by Au ion precursors, and reduced to form Au nanoparticles (AuNPs) on the MCF surfaces. These decorated MCF surfaces were immobilized with enzyme acetylcholinesterase (AChE), modified on screen-printed carbon electrodes and tested for electrochemical responses with acetylthiocholine. AuNPs were successfully distributed within the pores for both types of MCFs. Before the functional biosensor electrochemical tests, calcination seemed more promising than solvent extraction due to periodic structure of pores, high surface area, less contamination and higher concentration of surface silanol groups available for grafting of the amine functional group. However, after immobilization of the AuNPs for electron transport improvement and enzyme immobilization, a few observations of biosensing performances were noteworthy. Firstly, having AuNPs distributed throughout the MCF structure did not help the electron transport. Results of reduced response currents from both types of MCFs compared to MCFs without AuNPs indicated that MCF walls were too thick to allow electron transport. Secondly, the higher concentration of surface silanol groups in calcined MCFs resulted in Ostwald’s ripening of small AuNPs giving bigger AuNPs than the case of solvent extraction. Therefore, although the AuNPs in enzyme biosensors are expected to help electron transport and enzyme immobilization, this study showed that although the former did not occur, the latter was well demonstrated. The smaller AuNPs in the solvent extraction case resulted in higher surface area than the bigger AuNPs in the calcination case. This was the reason why the response current was higher for the solvent extracted MCFs compared to the calcined MCFs.

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Drying induced phase separation in poly(styrene)–poly(ethylene glycol)–chlorobenzene system

Abstract

The morphological studies of poly(styrene)–poly(ethylene glycol)–chlorobenzene films have been performed using scanning electron microscopy. The average diameter of the holes present in the coatings decreased from 7.68 to 3.74 µm with the increase in the polymer content from 5 to 10%. The solvent played a major role in forming ordered porous polymer films. Asymmetric membrane formed at different concentrations of the ternary system. The effects of various parameters like polymer mass fraction, initial film thickness, and technique of application, on the pore size and uniformity have been studied. The membranes are formed at different concentrations of the ternary system.

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Fabrication of Al 2 O 3 aerogel-SiO 2 fiber composite with enhanced thermal insulation and high heat resistance

Abstract

The thermal-resistance Al2O3 aerogels and Al2O3 aerogel-SiO2 fiber composite by using inorganic aluminum salt as the precursor were synthesized by the sol–gel process. The method was straightforward, inexpensive, and safe. Furthermore, it was found that the as-prepared Al2O3 aerogel had high crystal phase transition temperature. As the heat treatment temperature increased to 900 °C, the crystal phase transition from γ-AlOOH to γ-Al2O3 occurred within the Al2O3 aerogel. Meanwhile, the Al2O3 aerogel-SiO2 fiber composite exhibited high Young’s modulus of tensile strength up to 6.59 MPa and low thermal conductivity at 35 °C (0.028 W/(m K)) and high temperature of 600 °C (0.033 W/(m K)). In addition, the results indicated that the Al2O3 aerogel-SiO2 fiber composite had the moderate hydrophobic property as well as mechanical property.

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Mo based electrocatalyst with N, P co-doped mesoporous carbon as matrix for overall water splitting H 2 production

Abstract

In an attempt to explore high efficient and low cost electrocatalyst in H2 evolution reaction (HER), Mo2C nanoparticles with the size about 8 to 10 nm are loaded on N, P co-doped mesoporous carbon matrix successfully with Na2MoO4 and carbonated beverage as precursors. The obtained electrocatalyst, Mo2C@NPC, possesses small dimension with the size about 200 to 300 nm. Mo2C@NPC exhibits very excellent HER activity. It exhibits excellent electrocatalytic performance in basic condition, with overpotential 60 mV and Tafel slope 63 mV dec−1 to get 10 mA cm−2 current density for H2 evolution reaction (HER). To realize overall H2O splitting, Co was doped into Mo2C@NPC and a new electrocatalyst, named as Co/Mo2C@NPC was obtained. Co/Mo2C@NPC shows outstanding oxygen evolution reaction (OER) performance. Under same condition, to get current with density of 10 mA cm−2, Co/Mo2C@NPC merely need 360 mV. The electrocatalyst also possesses excellent durability, after 1000 cycles as well as 10 h long-term HER and OER tests, the current keeps stable. To achieve overall H2O splitting, an electrolyzer is constructed with Mo2C@NPC and Co/Mo2C@NPC as cathode and anode. To get a current with density 10 mA cm−2, it only needs a voltage of 1.60 V. We expect Mo2C@NPC and Co/Mo2C@NPC electrocatalyst can act as a new material for overall H2O splitting.

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Effect of preparation conditions of benzene bridged Ti incorporated periodic mesoporous organosilicas on selectivity improvement of cyclohexene epoxidation

Abstract

Benzene bridged Ti incorporated periodic mesoporous organosilicas (Ti-PMOs) was prepared following an in situ hydrothermal method by using P123 as a structure directing agent in acidic condition, tetrabutyl titanate (TBOT) as titanium source, tetraethoxysilane (TEOS) as inorganic Si-source and 1, 4-bis(triethoxysilyl)benzene (BTEB) as organic Si-source. The effects of preparation conditions of Ti-PMOs, mole ratio of TEOS/BTEB and ageing time, on the catalytic performance for the cyclohexene epoxidation with tertbutyl hydroperoxide as an oxidant agent were investigated. By means of a variety of characterized method, the results showed that the proper mole ratio of TEOS/BTEB was 3:1, which was favor of maintaining good mesoporous structure, ageing time of preparation mixture solution was a key factor to improve the catalytic performance of Ti-PMOs. NH3-TPD indicated that sample prepared at ageing time 48 h had more readily exposed active titanium site, which significantly improve the selectivity of cyclohexene oxide to 97.7% from 37.7% at 24 h ageing time. The hydrophobic group of benzene bridged on the pore wall was benefit for the approach of cyclohexene and formation of the active tetravalent titanium.

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Opacified graphene-doped silica aerogels with controllable thermal conductivity

Abstract

In this work, we developed a new type of thermal insulation materials by combining the silica aerogel (SiO2) and graphene (G) followed by aging and supercritical drying. The effects of different G/SiO2 mass ratios on the microstructures and properties of opacified G/SiO2-x composite aerogels were investigated. The results showed that the graphene was well-distributed in the SiO2 matrix. Meanwhile, the opacified composite aerogels showed high-specific surface area (~ 1000 m2/g). Due to the unique bandgap feature and conjugated large π bond of graphene, the thermal insulation property of G/SiO2-x composite aerogels was enhanced in contrast with the pure SiO2 aerogel. Moreover, a possible mechanism of heat transfer was discussed to interpret the result.

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Solvothermal synthesis of porous conjugated polymer with high surface area for efficient adsorption of organic and biomolecules

Abstract

Aimed to prepare high efficient dye sorbent and control water pollution, herein we utilized solvothermal method to synthesize porous polyimide (PI) polymer with a large surface area using DMSO as solvent. Unlike the solid-state thermal polymerized PI with low surface area of 5 m2g−1, this PI material prepared in DMSO solvent possessed a large surface area of 430 m2g−1, which was beneficial for adsorption of organic dye in waste water, achieving a max MO adsorption of 200 mg g−1 three times higher than that of multiwalled carbon nanotube. The adsorption kinetics of dye molecules on PI was investigated in detail and the R2 value of 0.99071 for pseudo-second-order model confirms the adsorption was fitted best with Langmuir isotherm.

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