Oxide‐Supported IrNiOx Core–Shell Particles as Efficient,Cost‐Effective,and Stable Catalysts for Electrochemical Water Splitting

Active and highly stable oxide‐supported IrNiO_x core–shell catalysts for electrochemical water splitting are presented. IrNi_x@IrO_x nanoparticles supported on high‐surface‐area mesoporous antimony‐doped tin oxide (IrNiO_x /Meso‐ATO) were synthesized from bimetallic IrNi_x precursor alloys (PA‐IrNi_x /Meso‐ATO) using electrochemical Ni leaching and concomitant Ir oxidation. Special emphasis was placed on Ni/NiO surface segregation under thermal treatment of the PA‐IrNi_x /Meso‐ATO as well as on the surface chemical state of the particle/oxide support interface. Combining a wide array of characterization methods, we uncovered the detrimental effect of segregated NiO phases on the water splitting activity of core–shell particles. The core–shell IrNiO_x /Meso‐ATO catalyst displayed high water‐splitting activity and unprecedented stability in acidic electrolyte providing substantial progress in the development of PEM electrolyzer anode catalysts with drastically reduced Ir loading and significantly enhanced durability.     

Oxide‐Supported IrNiOx Core–Shell Particles as Efficient,Cost‐Effective,and Stable Catalysts for Electrochemical Water Splitting

Active and highly stable oxide‐supported IrNiO_x core–shell catalysts for electrochemical water splitting are presented. IrNi_x@IrO_x nanoparticles supported on high‐surface‐area mesoporous antimony‐doped tin oxide (IrNiO_x /Meso‐ATO) were synthesized from bimetallic IrNi_x precursor alloys (PA‐IrNi_x /Meso‐ATO) using electrochemical Ni leaching and concomitant Ir oxidation. Special emphasis was placed on Ni/NiO surface segregation under thermal treatment of the PA‐IrNi_x /Meso‐ATO as well as on the surface chemical state of the particle/oxide support interface. Combining a wide array of characterization methods, we uncovered the detrimental effect of segregated NiO phases on the water splitting activity of core–shell particles. The core–shell IrNiO_x /Meso‐ATO catalyst displayed high water‐splitting activity and unprecedented stability in acidic electrolyte providing substantial progress in the development of PEM electrolyzer anode catalysts with drastically reduced Ir loading and significantly enhanced durability.     

微孔-介孔复合结构分子筛的合成及表征研究

以工业现有的ZSM-5作为原料,经一定化学处理的ZSM-5作为部分硅铝源,与介孔分子筛的凝胶在水热条件下进行组装得到具有微孔、介孔双孔分布的复合分子筛,并采用XRD、N2吸附脱附、IR、SEM、TEM等测试手段对合成样品进行分析表征,考察了主要合成条件对分子筛性能的影响.结果表明,合成过程中微孔与介孔结构之间会相互转化,样品中微孔与介孔特征峰存在此消彼长的关系.非临氢反应结果表明,复合分子筛具有较高的异构化选择性.     

Aluminosilicates with different pores structure in the synthesis of 2,2,4-trimethyl-1,2-dihydroquinoline and <Emphasis Type="Italic">N</Emphasis>-phenyl-2-propanimine

Physicochemical characteristics of microporous zeolites of various structural type (FAU, BEA, MTW), micro-meso-macroporous zeolite (H-Ymmm), and mesoporous aluminosilicate (ASM) were studied. Their catalytic activity in the reaction of aniline with acetone was examined. It was found that 2,2,4-trimethyl-1,2-dihydroquinoline was the main reaction product on the catalysts H-Ymmm and ASM (selectivity up to 68% at 100% conversion of aniline), while the reaction on zeolites with microporous structure mainly gave N-phenyl-2-propanimine (selectivity up to 91%).     

Au／TS-1@Mesosilica双功能催化材料的制备及其催化丙烯直接环氧化性能

设计制备了一种新型微孔介孔复合核壳结构钛硅分子筛TS-1@Mesosilica（TS-l@Ms）,核为MFI结构钛硅分子筛TS-1,壳层为以非离子表面活性剂P123为模板剂组装形成的介孔氧化硅．壳层氧化硅具有三维蠕虫状孔道结构,有利于微孔和介孔部分的连通及反应物和产物的扩散．通过沉积沉淀法将金纳米粒子负载在壳层介孔孔道,和TS-1中的钛活性中心协同,形成适合于C3H6和H2、O2直接气相环氧化制备环氧丙烷（PO）的双功能催化材料．实验结果表明,Au／TS-1@MS在空速8000mLg-h、温度473K条件下连续反应132h,活性和选择性没有明显下降,丙烯转化率保持在3．7％左右,PO选择性87％以上．     

A hierarchically assembled mesoporous ZnO hemisphere array and hollow microspheres for photocatalytic membrane water filtration

A mesoporous ZnO hemisphere array has been prepared via a topotactic transition of Zn(4)(OH)(6)CO(3)·H(2)O (ZCHH) by chemical bath deposition. Each hemisphere is comprised of a radially oriented nanoflake shell grown on the hemispherical interior. Reaction time-dependent SEM analysis shows that the morphological formation of ZCHH involves a deposition-growth-secondary growth-redeposition procedure. Upon calcination, ZCHH readily decomposes to nanocrystalline wurtzite-phase ZnO without significant change in morphology, and the release of CO(2) and H(2)O from ZCHH creates an additional mesoporous structure in both hemispherical interior and nanoflake shell. A similar process but without using a substrate has been developed for synthesis of mesoporous ZnO hollow microspheres in powder form. Both the elaborated superstructured photocatalysts consisting of mesoporous nanoflakes have been demonstrated to exhibit excellent performances in the photocatalytic membrane filtration.     

Optical and gas sensing properties of mesoporous hollow ZnO microspheres fabricated via a solvothermal method

Mesoporous,hollow Zn O microspheres were synthesized via a hydrothermal method,using glycerol and zinc acetate as the starting materials.XRD and FESEM analysis showed that the surface morphology of the spheres with a Wurtzite structure could be reasonably adjusted by varying the weight ratio(Rw) of Zn(CH3COO)2 2H2O:H2O:C3H8O3.The responses of the gas sensor based on the spheres to 100 ppm ethanol and 100 ppm acetone are 18.9 and 10.4,respectively.The response and recovery times of the sensor to ethanol and acetone are 2 s and 3 s,3 s and 5 s,respectively.The hollow spheres show an intense UV emission at 392 nm and a broad blue-green emission at 488 nm.Interestingly,a light trapping phenomenon is revealed by UV emission and scattering measurements on the microspheres,which can be attributed to the mesoporous shell and hollow structure of the microsphere.     

One‐Step Synthesis of Hybrid Core–Shell Metal–Organic Frameworks

Epitaxial growth of MOF‐on‐MOF composite is an evolving research topic in the quest for multifunctional materials. In previously reported methods, the core–shell MOFs were synthesized via a stepwise strategy that involved growing the shell‐MOFs on top of the preformed core‐MOFs with matched lattice parameters. However, the inconvenient stepwise synthesis and the strict lattice‐matching requirement have limited the preparation of core–shell MOFs. Herein, we demonstrate that hybrid core–shell MOFs with mismatching lattices can be synthesized under the guidance of nucleation kinetic analysis. A series of MOF composites with mesoporous core and microporous shell were constructed and characterized by optical microscopy, powder X‐ray diffraction, gas sorption measurement, and scanning electron microscopy. Isoreticular expansion of microporous shells and orthogonal modification of the core was realized to produce multifunctional MOF composites, which acted as size selective catalysts for olefin epoxidation with high activity and selectivity.     

Redox‐ and Temperature‐Controlled Drug Release from Hollow Mesoporous Silica Nanoparticles

A controlled drug‐delivery system has been developed based on mesoporous silica nanoparticles that deliver anticancer drugs into cancer cells with minimized side effects. The copolymer of two oligo(ethylene glycol) macromonomers cross‐linked by the disulfide linker N,N′‐bis(acryloyl)cystamine is used to cap hollow mesoporous silica nanoparticles (HMSNs) to form a core/shell structure. The HMSN core is applied as a drug storage unit for its high drug loading capability, whereas the polymer shell is employed as a switch owing to its redox/temperature dual responses. The release behavior in vitro of doxorubicin demonstrated that the loaded drugs could be released rapidly at higher temperature or in the presence of glutathione (GSH). Thus, the dual‐stimulus polymer shell exhibiting a volume phase transition temperature higher than 37 °C can effectively avoid drug leakage in the bloodstream owing to the swollen state of the shell. Once internalized into cells, the carriers shed the polymer shell because of cleavage of the disulfide bonds by GSH, which results in the release of the loaded drugs in cytosol. This work may prove to be a significant development in on‐demand drug release systems for cancer therapy.     

Sulfonated microporous organic-inorganic hybrids as strong Bronsted acids

It has been discovered that the use of excess zirconium in reactions with 4,4'-biphenyl and 4,4'-terphenylbis(phosphonic acid) in DMSO or DMSO-ethanol mixtures produces microporous inorganic-organic hybrids. Surface areas of 400 m(2)/g and pore sizes in the range of 10-20 A in diameter are routinely obtained. These materials are readily sulfonated with SO(3) under pressure to yield strong Bronsted acids. The acid strength, measured by (13)C NMR shifts of acetone and cyclopentanone in contact with the sulfonates, indicates an acidity close to that of 100% H(2)SO(4). Condensation and cracking reactions were obtained for both ketones under mild conditions. A working hypothesis is presented to account for the high surface area and microporosity. The combination of high surface areas and pore dimensions that are between those of zeolites and mesoporous silicas commends these materials for applications in separations, ion exchange, and catalysis.     

MCM-41介孔分子筛掺杂的微孔型聚合物电解质的制备与表征

以介孔分子筛MCM-41作填料,丙酮与二甲基甲酰胺混合液为溶剂,用直接造孔成膜的方法制备了微孔型聚合物电解质膜.该法避免使用造孔增塑剂,既简化了制膜工序,又减少电池中副反应的发生,使电池性能得以提高.MCM-41分子筛具有六方有序排列的单一柱状孔道结构和纳米级的粒子尺度,其骨架结构单元与一般聚合物电解质常用的纳米SiO2填料具有相同的化学成分,该分子筛堆积时形成的表面空隙及其独有的一维介孔孔道对聚合物电解质微孔的形成与连通、电导率的提高都具有重要作用,是一种极具实用价值的新型无机填料.     

Microporous organic nanotube networks from hyper cross-linking core-shell bottlebrush copolymers for selective adsorption study

We report a synthesis of microporous organic nanotube networks (MONNs) by a combination of hyper cross-linking and molecular templating of core-shell bottlebrush copolymers.The intrabrush and interbrush cross-linking of polystyrene (PS) shell layer in the core-shell bottlebrush copolymers led to the formation of micropores and large-sized nanopores (meso/macrospores) in MONNs,respectively,while selective removal of polylactide (PLA) core layer generated mesoporous tubular structure.The size of PLA-templated mesoporous cores and porous structure both at micro-and meso-scale could be controlled by simple tuning of the ratio of core/shell or the PLA core fraction in the bottlebrush precursors.Moreover,the resultant MONNs showed a highly selective adsorption capacity for the positively charged dyes on the basis of multi-porosity and carboxylate group-rich structure.In addition,MONNs also exhibited effective performance in size-selective adsorption of biomacromolecules.This work represents a new avenue for the preparation of MONNs and also provides a new application for molecular bottlebrushes in nanotechnology.     

Synthesis of high surface area Al-containing mesoporous silica from calcined and acid leached kaolinites as the precursors

Al-containing mesoporous silicas were synthesized by hydrothermal treatment of microporous silica prepared by selectively acid leached metakaolinites with Si/Al = 3.9-92.5 mixed with a surfactant of cetyltrimethylammonium bromide (CTABr). The specific surface area of the products increased with higher surfactant/microporous silica (surf/Si) ratio and Si/Al ratio of the microporous silica, reaching about 1400 m2/g at CTABr/Si 0.1 and Si/Al 40. The XRD patterns of these products show a hexagonal (100) peak with the lattice parameter a0=4.2-4.3 nm and the N2 adsorption isotherms show steep increase of adsorption between relative pressure of 0.3 and 0.4. Hexagonal mesoporous microstructure is observed by high resolution TEM. The pore size distributions of the products show a sharp peak at 2.8 nm by the BJH method. The high specific surface area of the present mesoporous samples is attributed to the lower matrix density and surface roughness of mesopore wall. The highest specific surface area of the products reached up to 1420 m2/g and this value is apparently higher than those reported in hexagonal mesoporous silicas. A unique microporous structure of the starting material is thought to be related to achieve such a high specific surface area of the products.     

Fabrication of bimodal porous silicate with silicalite-1 core/mesoporous shell structures and synthesis of nonspherical carbon and silica nanocases with hollow core/mesoporous shell structures

In this work, an attempt has been made to modify the shape and nanostructure of core-shell materials, which have been usually generated on the basis of amorphous spherical cores. Novel core-shell silicate particles, each of which consists of a silicalite-1 zeolite crystal core and mesoporous shell (ZCMS), were synthesized for the first time. The ZCMS core-shell particles are unique because they are of pseudohexagonal prismatic shape and have hierarchical porosity of both a uniform microporous core and a mesoporous shell coexisting in a particle framework. The nonspherical bimodal porous core-shell particles were then utilized as templates to fabricate a new carbon replica structure. Interestingly, the pore replication process was carried out only through the mesopores in the shell, and not through the micropores due to the narrower micropore size in the core, resulting in nonspherical carbon nanocases with a hollow core and mesoporous shell (HCMS) structure. Nonspherical silica nanocases with HCMS structure were also generated by replication using the carbon nanocases as templates, which are not possible to synthesize through other synthetic methods. Interestingly, the pseudohexagonal prismatic shape of the zeolite crystals was transferred onto the carbon and silica nanocases.     

Adsorption of hydrogen isotopes on micro- and mesoporous adsorbents with orderly structure

The equilibrium and dynamic adsorption data of H(2) and D(2) on different micro- and mesoporous adsorbents with orderly structure including 3A, 4A, 5A, Y, and 10X zeolites; carbon CMK-3; silica SBA-15; and so forth were collected. Critical effect of the nanodimension of adsorbents on the adsorption behavior of hydrogen and its isotopes is shown. The highest adsorption capacity was observed at pore size 0.7 nm, but equal or even larger isotope difference in the equilibrium adsorption was observed at larger pore sizes, whereas the largest isotope difference in the dynamic adsorption was observed at 0.5 nm. The adsorption rate of D(2) is larger than that of H(2) in microporous adsorbents, but the sequence could be switched over in mesoporous materials. Linear relationship was observed between the adsorption capacity for hydrogen and the specific surface area of adsorbents although the adsorbents are made of different material, which provides a convincing proof of the monolayer mechanism of hydrogen adsorption. The linear plot for microporous adsorbents has a larger slope than that for mesoporous adsorbents, which is attributed to the stronger adsorption potential in micropores.     

Solution‐blown nylon 6–chitosan core–shell nanofiber for highly efficient affinity adsorption

A facile spinning‐based strategy was developed to fabricate chitosan (CS) surface nanofiber‐based affinity membranes for protein adsorption. The core–shell nanofiber mat of nylon 6–CS was prepared via coaxial solution blowing process. The nanofibers have a diameter range of 60–300 nm. The core–shell structure was confirmed by transmission electron microscopy, and CS was observed as a thin layer that uniformly adhered to the core. The dye ligand of cibacron blue F3GA (CB F3GA) was further covalently immobilized on the nanofibers with a content of 425 µmol/g. The pristine and CB F3GA‐attached mats were studied in protein adsorption. High bovine serum albumin adsorption capacities of 91.9 and 219.6 mg/g were obtained for pristine and CB F3GA‐attached mats, respectively. Given its properties of high flux rate and low pressure drop, CB F3GA‐attached nylon 6–CS nanofiber mat meets the requirements of highly effective affinity membrane chromatography. Copyright © 2016 John Wiley & Sons, Ltd.     

Coloring–decoloring behavior of fluoroalkyl end‐capped 2‐acrylamido‐2‐methylpropanesulfonic acid oligomer/acetone composite in methanol

A reddish‐brown fluoroalkyl end‐capped 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS) oligomer/acetone composite was prepared by heating the white oligomer powder with acetone at 80 °C for 3 h. The color was not observed in the corresponding non‐fluorinated AMPS oligomer/acetone composite, which was prepared under similar conditions. The coloring was probably caused by the formation of acetone polyaldol condensation products in the fluorinated oligomeric gel network cores. The colored R_F‐(AMPS)_n‐R_F/acetone composite powders were stable and did not exhibit any color change after 2 years in natural light at room temperature. The colored composite powders dissolved in methanol to give a reddish‐brown solution at room temperature. However, the retro‐polyaldol condensation decolored the solution after 1 day at room temperature. This is the first example of the retro‐aldol polycondensation of acetone under mild conditions. The decoloration increased by between 38‐ and 70‐fold under UV irradiation, compared with that in dark conditions. The coloring–decoloring behavior was consistent and repeatable; therefore our fluorinated oligomer/acetone composites are promising candidates for new fluorinated coloring materials. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2555–2564     

Fabrication of Microporous Metal–Organic Frameworks in Uninterrupted Mesoporous Tunnels: Hierarchical Structure for Efficient Trypsin Immobilization and Stabilization

Hierarchically porous metal–organic frameworks (HP‐MOFs) are promising in various applications. Most reported HP‐MOFs are prepared based on the generation of mesopores in microporous frameworks, and the formed mesopores are connected by microporous channels, limiting the accessibility of mesopores for bulky molecules. A hierarchical structure is formed by constructing microporous MOFs in uninterrupted mesoporous tunnels. Using the confined space in as‐prepared mesoporous silica, highly dispersed metal precursors for MOFs are coated on the internal surface of mesoporous tunnels. Ligand vapor‐induced crystallization is employed to enable quantitative formation of MOFs in situ, in which sublimated ligands diffuse into mesoporous tunnels and react with metal precursors. The obtained hierarchically porous composites exhibit record‐high adsorption capacity for the bulky molecule trypsin. The thermal and storage stability of trypsin is improved upon immobilization on the composites.     

磺酸基团功能化的碳-硅介孔复合材料的制备及其在生物柴油绿色合成中的应用(英文)

利用化学浸渍法将蔗糖负载到 SBA-15 介孔材料孔道内部, 高温炭化形成的多聚苯环经发烟硫酸气相磺化处理后, 得到磺酸基团功能化的新型碳-硅介孔复合材料. 发烟硫酸气相磺化处理是该材料合成的关键步骤. X 射线衍射、扫描电镜和氮气吸附结果表明, 碳-硅介孔复合材料经磺酸化处理保持了高度有序的介孔结构. 热重、傅里叶变换的红外光谱及吡啶吸附红外光谱结果证明, 磺酸功能基团成功的嫁接于碳-硅介孔复合材料孔道的内表面, 反应活性中心为 Br?nsted 酸, 酸密度在 0.09~0.70 mmol/g 可以有效调变. 当碳负载量为 35% 时, 该复合材料在生物柴油的绿色合成中显示出最优的催化性能, 且可重复使用 3 次以上.     

Hydrolytic Transformation of Microporous Metal–Organic Frameworks to Hierarchical Micro‐ and Mesoporous MOFs

A new approach to the synthesis of hierarchical micro‐ and mesoporous MOFs from microporous MOFs involves a simple hydrolytic post‐synthetic procedure. As a proof of concept, a new microporous MOF, POST‐66(Y), was synthesized and its transformation into a hierarchical micro‐ and mesoporous MOF by water treatment was studied. This method produced mesopores in the range of 3 to 20 nm in the MOF while maintaining the original microporous structure, at least in part. The degree of micro‐ and mesoporosity can be controlled by adjusting the time and temperature of hydrolysis. The resulting hierarchical porous MOF, POST‐66(Y)‐wt, can be utilized to encapsulate nanometer‐sized guests such as proteins, and the enhanced stability and recyclability of an encapsulated enzyme is demonstrated.