Hierarchically macro/mesoporous silica monoliths constructed with interconnecting micrometer-sized unit rods

Under typical dilute reactant compositions (3 ~ 5 wt% of surfactant template concentration) and conventional hydrothermal conditions for mesoporous materials synthesis, successful preparation of hierarchically macro/mesoporous silica monoliths was reported in this paper. The resultant materials were characterized by a series of techniques including powder X-ray diffraction, N₂ adsorption–desorption, SEM, TEM/EDS, and Hg porosimetry. A new kind of stable and hierarchically porous pure silica monoliths was confirmed, which are featured with highly ordered mesoporous structures, rod-shaped unit particles, large specific surface area of 492 m²/g, continuous macropores of about 4.0 μm in size and high macropore volume of about 13.1 cm³/g. Moreover, using the resultant silica monoliths as hard templates, carbon monoliths have been successfully replicated, which inherit the structural characters of parent silica materials. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Amphiphilic block copolymers directed synthesis of mesoporous nickel-based oxides with bimodal mesopores and nanocrystal-assembled walls

Mesoporous late-transition metal oxides have great potential in applications of energy,catalysis and chemical sensing due to their unique physical and chemical properties.However,their synthesis via the flexible and scalable soft-template method remain a great challenge,due to the weak organic-inorganic interaction between the frequently used surfactants(e.g.,Pluronic-type block copolymers) and metal oxide precursors,and the low crystallization temperature of metal oxides.In this study,ordered mesoporous NiO with dual mesopores,high surface area and well-interconnected crystalline porous frameworks have been successfully synthesized via the facile solvent evaporation-induced co-assembly(EICA) method,by using lab-made amphiphilic diblock copolymer polystyrene-b-poly(4-vinylpyridine)(PS-b-P4 VP) as both the structure-directing agent(the soft template) and macromolecular chelating agents for nickel species,THF as the solvent,and nickel acetylacetonate(Ni(acac)2) as inorganic precursor.Similarly,by using Ni(acac)2 and Fe(acac)3 as the binary precursors,ordered mesoporous Fedoped NiO materials can be obtained,which have bimodal mesopores of large mesopores(32.5 nm) and secondary mesopores(4.0-11.5 nm) in the nanocrystal-assembled walls,high specific surface areas(～74.8 m~2/g) and large pore value(～0.167 cm~3/g).The obtained mesoporous Fe-doped NiO based gas sensor showed superior ethanol sensing performances with good sensitivity,high selectivity and fast response-recovery dynamics.     

Ordered mesoporous silicon carbide-derived carbon for high-power supercapacitors

Micro/mesoporous carbon was prepared by chlorination of ordered mesoporous silicon carbide derived from magnesio-thermal reduction of templated carbon-silica precursors. These materials were then used as active materials for electrochemical capacitors and characterized in 1.5 M NEt₄BF₄/AN. The electrodes showed outstanding rate capability (90% of capacity retention at 1 V/s and time constant of 1 s) with high specific areal capacitance (0.5 F/cm² of electrode), that makes such hierarchical porous carbons promising for high power and energy density supercapacitors.     

Electrorheological effect of carbonaceous materials with hierarchical porous structures

Carbonaceous materials with different hierarchical porous structures for electrorheological (ER) dispersed phase have been synthesized by carbonization of as-prepared starch/silica precurser at different temperatures. The N₂ adsorption isotherms show that Cmeso-700 and Cmeso-500 particles have the BET surface areas of 1028 and 603 m² g⁻¹, respectively. They both have the mesoporous pores with size of about 4.6 nm and the microporous pores (1.1 and 1.5 nm, respectively). The BET surface areas and C/O atomic ratio of porous carbon materials can be increased with the carbonization temperatures. The rheological measurements indicate that the Cmeso-700 and Cmeso-500 ERF have the better ER effect resulted from their hierarchical porous structures. The shear stress of Cmeso-700 ERF is 900 Pa at 1000 s⁻¹ under 3 kV mm⁻¹, which is almost 4.5 times larger than that of Cmicro-350 ERF. The mesoporous carbon ERFs also show the better sedimentation stability than microporous carbon ERFs. The different ER effect of carbonaceous particles may derive from their different dielectric polarization property induced by the hierarchical porous structures.     

Highly Crystalline Mesoporous C60 with Ordered Pores: A Class of Nanomaterials for Energy Applications

Highly ordered mesoporous C₆₀ with a well‐ordered porous structure and a high crystallinity is prepared through the nanohard templating method using a saturated solution of C₆₀ in 1‐chloronaphthalene (51 mg mL^?1) as a C₆₀ precursor and SBA‐15 as a hard template. The high solubility of C₆₀ in 1‐chloronaphthalene helps not only to encapsulate a huge amount of the C₆₀ into the mesopores of the template but also supports the oligomerization of C₆₀ and the formation of crystalline walls made of C₆₀. The obtained mesoporous C₆₀ exhibits a rod‐shaped morphology, a high specific surface area (680 m² g^?1), tuneable pores, and a highly crystalline wall structure. This exciting ordered mesoporous C₆₀ offers high supercapacitive performance and a high selectivity to H₂O₂ production and methanol tolerance for ORR. This simple strategy could be adopted to make a series of mesoporous fullerenes with different structures and carbon atoms as a new class of energy materials.     

Fabrication of synthetic opals composed of mesoporous SnO2 spheres with an anodization-assisted double template process

Synthetic opals composed of mesoporous SnO₂ spheres were successfully fabricated from anodization of Sn opals, double templated from polystyrene opals. The mesoporous SnO₂ spheres were 440 nm in diameter containing mesopores of 20–40 nm. The resultant mesoporous SnO₂ opals possessed a high specific surface area of 196 m²/g and a grain size of 12 nm as estimated from XRD patterns. Such a hierarchical structure of SnO₂ is a promising candidate for applications in gas sensors, catalysts, and electrode materials since the regularity of the sub-micron opal structure eases transfers of relevant chemical species within the structure while the mesoporosity of the constituent SnO₂ spheres offers sufficient functioning surfaces for targeted applications.     

Preparation of POSS-based organic–inorganic hybrid mesoporous materials networks through Schiff base chemistry

The synthesis of novel POSS-based organic–inorganic hybrid mesoporous materials networks functionalized with amine groups through Schiff base chemistry is reported. The material shows uniform mesoporous size. Nitrogen sorption analyses give high specific surface areas of 641–1103 m² g⁻¹ with pore volumes of 0.47–0.53 mL g⁻¹. The combined results of FTIR, solid ¹³C NMR and ²⁹Si NMR show that the POSS building blocks are successfully weaved in the porous structure without obvious alteration of the POSS structural characteristics. The hybrid materials show excellent thermal stability.     

Novel synthesis of high-surface-area ordered mesoporous TiO2 with anatase framework for photocatalytic applications

Ordered mesoporous TiO₂ materials with an anatase frameworks have been synthesized by using a cationic surfactant cetyltrimethylammonium bromide (C₁₆TMABr) as a structure-directing agent and soluble peroxytitanates as Ti precursor through a self-assembly between the positive charged surfactant S⁺ and the negatively charged inorganic framework I^? (S⁺I^? type). The low-angle X-ray diffraction (XRD) pattern of the as-prepared mesoporous TiO₂ materials indicates a hexagonal mesostructure. XRD and transmission electron microscopy results and nitrogen adsorption–desorption isotherms measurements indicate that the calcined mesoporous TiO₂ possesses an anatase crystalline framework having a maximum pore size of 6.9 nm and a maximum Brunauer–Emmett–Teller specific surface area of 284 m² g^?1. This ordered mesoporous anatase TiO₂ also demonstrates a high photocatalytic activity for degradation of methylene blue under ultraviolet irradiation.     

Highly Ordered Mesoporous Tungsten Oxides with a Large Pore Size and Crystalline Framework for H2S Sensing

An ordered mesoporous WO₃ material with a highly crystalline framework was synthesized by using amphiphilic poly(ethylene oxide)‐b‐polystyrene (PEO‐b‐PS) diblock copolymers as a structure‐directing agent through a solvent‐evaporation‐induced self‐assembly method combined with a simple template‐carbonization strategy. The obtained mesoporous WO₃ materials have a large uniform mesopore size (ca. 10.9 nm) and a high surface area (ca. 121 m² g^?1). The mesoporous WO₃‐based H₂S gas sensor shows an excellent performance for H₂S sensing at low concentration (0.25 ppm) with fast response (2 s) and recovery (38 s). The high mesoporosity and continuous crystalline framework are responsible for the excellent performance in H₂S sensing.     

Effect of yttrium on the formation of nanostructured mesoporous CeO<Subscript>2</Subscript>

Mesoporous CeO₂ and yttrium doped CeO₂ (YDC) were prepared by a sol–gel process and characterized by a variety of techniques. XRD patterns showed that the undoped and doped samples had a cubic fluorite structure. The grain size decreased from 24.8 to 6.1 nm at 500 °C for pure CeO₂ and YDC, respectively. N₂ adsorption–desorption isotherms showed that the samples possessed typical mesopore characteristics. The BET specific surface area of the samples increased from 23.04 to 151.49 m²/g for 300 °C calcination after mesoporous CeO₂ was doped with Y. It is found that the introduction of Y can inhibit the grain growth, and the presence of the pores also can be related to this obstacle to grain growth. These results are of great significance for the control of porous microstructure, crystallinity, and applications for the development of nanostructured mesoporous materials.     

Tunable activity in electrochemical reduction of oxygen by gold–polyaniline porous nanocomposites

Oxygen electrochemical reduction on gold–polyaniline (Au–PANI) porous nanocomposite-modified glassy carbon electrode in basic media was described. The as-prepared Au–PANI porous nanocomposite showed superior tunable activity for electrochemical reduction of oxygen. The specific surface area of Au–PANI porous nanocomposites was evaluated to be about 11.3 m² g⁻¹ through a convenient voltammetric approach. Rotating ring-disk electrode experiments further demonstrated the number of electrons exchanged in oxygen reduction increased from 2e to 4e with increasing the trigger potential from 300, to 500, 700 mV. The tunable activity in electrochemical reduction of oxygen was achieved as a result of positive potential-induced formation and reduction of Au surface oxide. However, the tunable oxygen reduction reaction is fit for applying potential in a linear positive-going potential sweep. Irreversible ORR tunability was found after a more active surface formed at 700 mV. To optimize the applied potential window on these Au-based porous materials has potential applications such as in electrochemical sensing, fuel cells, or getting rid of the interference from the coexisted substances.     

3D-printed porous electrodes for advanced electrochemical flow reactors: A Ni/stainless steel electrode and its mass transport characteristics

Porous electrodes have shown high performance in industrial electrochemical processes and redox flow batteries for energy storage. These materials offer great advantages over planar electrodes in terms of larger surface area, superior space time yield and enhanced mass transport. In this work, a highly ordered porous stainless steel structure was manufactured by 3D-printing and coated with nickel from an acidic bath by electrodeposition in a divided rectangular channel flow cell. Following the electrodeposition, the volumetric mass transport coefficient of this electrode was determined by the electrochemical reduction of 1.0×10⁻³ mol dm⁻³ of ferricyanide ions by linear sweep voltammetry and chronoamperometry. The convection diffusion characteristics are compared with other geometries to demonstrate the novelty and the advantages of 3D-printed porous electrodes in electrochemical flow reactors. Robust porous electrodes with tailored surface area, composition, volumetric porosity and flow properties are possible.     

多孔碳材料的制备

多孔碳材料不仅具有碳材料化学稳定高、导电性好等优点,由于多孔结构的引入,还具有比表面积高、孔道结构丰富、孔径可调等特点,在催化、吸附和电化学储能等方面都得到了广泛的应用。本文综述了微孔、介孔、大孔及多级孔碳等多孔碳材料的最新研究进展,重点介绍了多孔碳孔道结构的调控,并对多孔碳材料的应用进行了展望。     

Highly ordered Zn-doped mesoporous silica: An efficient catalyst for transesterification reaction

Designing highly ordered material with nanoscale periodicity is of great significance in the field of solid state chemistry. Herein, we report the synthesis of highly ordered 2D-hexagonal mesoporous zinc-doped silica using a mixture of anionic and cationic surfactants under hydrothermal conditions. Powder XRD, N₂ sorption, TEM analysis revealed highly ordered 2D-hexagonal arrangements of the pores with very good surface area (762 m² g⁻¹) in this Zn-rich mesoporous material. Chemical analysis shows very high loading of zinc (ca. 12.0 wt%) in the material together with retention of hexagonal pore structure. Interestingly, high temperature calcination resulted into zinc silicate phase, unlike any ZnO phase, which otherwise is expected under heat treatments. High surface area together with Zn loading in this mesoporous material has been found useful for the catalytic activity of the materials in the acid-catalyzed transesterification reactions of various esters under mild liquid phase conditions.     

Facile synthesis of ordered mesoporous molybdenum carbide electrocatalysts for high-performance hydrogen evolution reaction

In this study, a simple method was designed to prepare ordered mesoporous carbons embedded with molybdenum without any extreme conditions. We prepared three different ordered molybdenum carbide materials with mesoporous structures to explore the influence of the structure of molybdenum-based materials on the HER catalytic efficiency. The ordered mesoporous molybdenum carbide catalysts (CMK-3-MoCx, fCMK-3-MoCx, CMK-8-MoCx) were characterized by SEM, TEM, XRD, nitrogen adsorption-desorption and XPS. The HER is catalyzed efficiently on the three electrocatalysts, fCMK-3-MoCx shows the best HER electro-catalytic performance with a small onset potential of −0.06 V vs. RHE, a low tafel slope of 66 mV dec⁻¹ and a small over-potential value of 89 mV at 10 mA cm⁻². This excellent performance on HER is due to its high specific surface area and highly ordered mesoporous structure that resulted in excellent proton transport efficiency and high electron transfer rate. Our results provide a new research direction for the application of flat ordered mesoporous structures in catalysis.     

Bio-templated synthesis of highly ordered macro-mesoporous silica material for sustained drug delivery

The bimodal porous structured silica materials consisting of macropores with the diameter of 5–20 μm and framework-like mesopores with the diameter of 4.7–6.0 nm were prepared using natural Manchurian ash and mango linin as macropored hard templates and P123 as mesopore soft templates, respectively. The macroporous structures of Manchurian ash and mango linin were replicated with the walls containing highly ordered mesoporous silica as well. As-synthesized dual porous silica was characterized by scanning electron microscope (SEM), powder X-ray diffraction (XRD), transmission electron microscope (TEM) and nitrogen adsorption/desorption, fourier transform IR (FTIR) spectroscopy, and thermo-gravimetric analyzer (TGA). Ibuprofen (Ibu) was employed as a model drug and the release profiles showed that the dual porous material had a sustained drug delivery capability. And such highly ordered dual pore silica materials may have potential applications for bimolecular adsorption/separation and tissue repairing.     

Facile synthesis of 3D flowerlike α-FeOOH architectures and their conversion into mesoporous α-Fe2O3 for gas-sensing application

We reported a facile and efficient solution-based route to prepare novel flowerlike α-FeOOH architectures without any template or surfactant. Scanning electron microscope (SEM) images reveal that leaf-like nanosheets with a thickness about 40 nm assembled into flowerlike superstructures. On the basis of time-dependent experiments, a multistage reaction mechanism for the formation of the flowerlike α-FeOOH was proposed. After heat treatment, the flowerlike α-FeOOH could be converted into corresponding mesoporous α-Fe₂O₃. Transmission electron microscopy (TEM) images and porosity analysis showed that the nanosheets have porous walls with a pore size of about 7 nm. As a demonstration of potential application for gas-sensing materials, the mesoporous α-Fe₂O₃ nanostructures exhibited short response/recovery time within 5/10 s, and low response concentration of 1 ppm toward acetone vapors. Large specific surface area and mesoporous structure should be beneficial for the sensing properties of α-Fe₂O₃.     

Sol–gel synthesis of Na<Subscript>2</Subscript>CaSiO<Subscript>4</Subscript> and its in vitro biological behaviors

In this work we prepared the hybrid material (SG) by the sol–gel method through the reaction between tetraethylortosilicate (TEOS) and acetylacetonatepropyltrimethoxysilane (ACACSIL). We also immobilized the acetylacetonate on silica surface (GR) by the grafting method through the reaction between a commercial silica and ACACSIL. Infrared thermal analysis showed that these materials were thermally stable until 200 °C. SG is a microporous material and has surface area of 500 m² g⁻¹, average porous volume of 0.09 cm³ g⁻¹ and organic content of 1 mmol g⁻¹. GR is a mesoporous material and has surface area of 300 m² g⁻¹, average porous volume of 0.7 cm³ g⁻¹ and organic content of 0.4 mmol g⁻¹. Iron(III) was coordinated to SG and GR resulting in the SG–Fe and GR–Fe silicas which were tested as catalysts on the aerobic epoxidation of cis-cyclooctene. SG–Fe yielded 100% of conversion and 94% of selectivity in epoxide whereas GR–Fe silica led to a maximum conversion of 50% and 100% of selectivity.     

Electrochemical detection of ultratrace nitroaromatic explosives using ordered mesoporous carbon

A sensitive electrochemical sensor has been fabricated to detect ultratrace nitroaromatic explosives using ordered mesoporus carbon (OMC). OMC was synthesized and characterized by scanning electron microscopy, transmission electron microscopy and nitrogen adsorption/desorption measurements. Glassy carbon electrodes functionalized with OMC show high sensitivity of 62.7 μA cm⁻² per ppb towards 2,4,6-trinitrotoluene (TNT). By comparison with other materials such as carbon nanotubes and ordered mesoporous silica, it is found that the high performance of OMC toward sensing TNT is attributed to its large specific surface area and fast electron transfer capability. As low as 0.2 ppb TNT, 1 ppb 2,4-dinitrotoluene and 1 ppb 1,3-dinitrobenzene can be detected on OMC based electrodes. This work renders new opportunities to detect ultratrace explosives for applications of environment protections and home securities against chemical warfare agents.     

Hybrid materials of MCM-41 functionalized by lanthanide (Tb, Eu) complexes of modified meta-methylbenzoic acid: Covalently bonded assembly and photoluminescence

Novel organic-inorganic mesoporous hybrid materials were synthesized by linking lanthanide (Tb³⁺, Eu³⁺) complexes to the mesoporous MCM-41 through the modified meta-methylbenzoic acid (MMBA-Si) using co-condensation method in the presence of the cetyltrimethylammonium bromide (CTAB) surfactant as template. The luminescence properties of these resulting materials (denoted as Ln-MMBA-MCM-41, Ln=Tb, Eu) were characterized in detail, and the results reveal that luminescent mesoporous materials have high surface area, uniformity in the ordered mesoporous structure. Moreover, the mesoporous material covalently bonded Tb³⁺ complex (Tb-MMBA-MCM-41) exhibits the stronger characteristic emission of Tb³⁺ and longer lifetime than Eu-MMBA-MCM-41 due to the triplet state energy of organic legend MMBA-Si matches with the emissive energy level of Tb³⁺ very well.