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1.
The large particle sizes, inert frameworks, and small pore sizes of mesoporous silica nanoparticles greatly restrict their application in the acidic catalysis. The research reports a simple and versatile approach to synthesize walnut‐like mesoporous silica nanospheres (WMSNs) with large tunable pores and small particle sizes by assembling with Beta seeds. The as‐synthesized Beta‐WMSNs composite materials possess ultrasmall particulate sizes (70 nm), large radial mesopores (≈30 nm), and excellent acidities (221.6 mmol g?1). Ni2P active phase is supported on the surface of Beta‐WMSNs composite materials, and it is found that the obtained composite spherical materials can reduce the Ni2P particle sizes from 8.4 to 4.8 nm with the increasing amount of Beta seeds, which can provide high accessibilities of reactants to the active sites. Furthermore, the unique large pores and ultrasmall particle sizes of Beta‐WMSNs samples facilitate the reduction of the diffusion resistance of reactants due to the short transporting length, thus the corresponding Ni2P/Beta‐WMSNs composite catalysts show the excellent hydrogenating activity compared to the pure Ni2P/WMSNs catalyst.  相似文献   

2.
Nanomeshes with highly regular, permeable pores in plane, combining the exceptional porous architectures with intrinsic properties of 2D materials, have attracted increasing attention in recent years. Herein, a series of 2D ultrathin metal–organic nanomeshes with ordered mesopores is obtained by a self‐assembly method, including metal phosphate and metal phosphonate. The resultant mesoporous ferric phytate nanomeshes feature unique 2D ultrathin monolayer morphologies ( ≈ 9 nm thickness), hexagonally ordered, permeable mesopores of ≈ 16 nm, as well as improved surface area and pore volume. Notably, the obtained ferric phytate nanomeshes can directly in situ convert into mesoporous sulfur‐doped metal phosphonate nanomeshes by serving as an unprecedented reactive self‐template. Furthermore, as advanced anode materials for Li‐ion batteries, they deliver excellent capacity, good rate capability, and cycling performance, greatly exceeding the similar metal phosphate‐based materials reported previously, resulting from their unique 2D ultrathin mesoporous structure. Therefore, the work will pave an avenue for constructing the other 2D ordered mesoporous materials, and thus offer new opportunities for them in diverse areas.  相似文献   

3.
Heteroatom doping is a promising strategy for improving the electrochemical performance of carbon materials. Herein, we spotlight an advantageous, simple, and efficient CVD synthesis of P-doped 3D cubic ordered mesoporous carbon (POMC) for the first time. The POMC was prepared by pyrolysis of acetylene/triphenylphosphine (C2H2/Ph3P) mixture at relatively low temperature over Fe-KIT-6 as a sacrificial template. The ensuing P-doped OMC showed an enhanced porous texture than an undoped counterpart with a specific surface area of 403.5 m2/g, pore volume of 0.545 cm3/g, average pore size of 4.64 nm and suitable heteroatom functionalities with P and O contents of 0.13% and 9.83%, correspondingly. The obtained POMC exhibited a much higher specific capacitance of 288F/g at 0.2 A/g (175F/g for OMC), good cyclic stability of 97.6 %, and good rate capability than pristine OMC in 6 M KOH. It is equivalent to or improved than various stated mono doped and even dual doped porous carbon electrodes. Furthermore, a symmetric supercapacitor (POMC//POMC) was fabricated with 1 M Na2SO4 aqueous neutral electrolyte exhibits high cycling stability (89.3%) even with a wide potential window (2.0 V) and offers a relatively high energy density (10.01 Wh/kg) with a power density of 300 W/kg.  相似文献   

4.
Ordered, hexagonal, mesoporous metal (Ti, Zr, V, Al)-phosphonate materials with microporous crystalline walls are synthesized through a microwave-assisted procedure by using triblock copolymer F127 as the template. Corresponding metal chlorides and ethylene diamine tetra(methylene phosphonic acid) are chosen as the inorganic precursors and the coupling molecule, respectively. X-ray diffractometry, transmission electron microscopy, N(2) sorption, and thermogravimetry measurements confirm that the obtained metal phosphonates possess a hierarchically porous structure with pore sizes of 7.1-7.5 nm and 1.3-1.7 nm for mesopores and micropores, respectively, and the metal phosphonate materials are thermally stable up to around 450 °C with the pore structure and hybrid framework well preserved. Magic angle spinning NMR, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy analyses indicate that the phosphonate groups are homogenously incorporated into the hybrid framework of the obtained materials. For the first time, the mesoporous hybrid materials are employed as the stationary phase in open tubular capillary electrochromatography technique for the separation of various substances including acidic, basic, and neutral compounds. These materials show good selectivity and reproducibility for this application.  相似文献   

5.
Nanocomposites with hierarchical pore structure hold great potentials for applications in the field of microwave-absorbing materials because of their lightweight and high-efficiency absorption properties. Herein, M-type barium ferrite (BaM) with ordered mesoporous structure (M-BaM) is prepared via a sol–gel process enhanced by mixed anionic and cationic surfactants. The surface area of M-BaM is enhanced almost ten times compared with BaM together with 40% reflection loss enhancing. Then M-BaM compounded with nitrogen-doped reduced graphene oxide (MBG) is synthesized via hydrothermal reaction in which the reduction and nitrogen doping of graphene oxide (GO) in situ occur simultaneously. Interestingly, the mesoporous structure is able to provide opportunity for reductant to enter the bulk M-BaM reducing its Fe3+ to Fe2+ and further forms Fe3O4. It requires an optimal balance among the remained mesopores in MBG, formed Fe3O4, and CN in nitrogen-doped graphene (N-RGO) for optimizing impedance matching and greatly increasing multiple reflections/interfacial polarization. MBG-2 (GO:M-BaM = 1:10) achieves the minimum reflection loss of −62.6 dB with an effective bandwidth of 4.2 GHz at an ultra-thin thickness of 1.4 mm. In addition, the marriage of mesoporous structure of M-BaM and light mass of graphene reduces the density of MBG.  相似文献   

6.
Porous carbon nitride (CN) spheres with partially crystalline frameworks have been successfully synthesized via a nanocasting approach by using spherical mesoporous cellular silica foams (MCFs) as a hard template, and ethylenediamine and carbon tetrachloride as precursors. The resulting spherical CN materials have uniform diameters of ca. 4 μm, hierarchical three-dimensional (3-D) mesostructures with small and large mesopores with pore diameters centered at ca. 4.0 and 43 nm, respectively, a relatively high BET surface area of ∼550 m2/g, and a pore volume of 0.90 cm3/g. High-resolution transmission electron microscope (HRTEM) images, wide-angle X-ray diffraction (XRD) patterns, and Raman spectra demonstrate that the porous CN material has a partly graphitized structure. In addition, elemental analyses, X-ray photoelectron spectra (XPS), Fourier transform infrared spectra (FT-IR), and CO2 temperature-programmed desorption (CO2-TPD) show that the material has a high nitrogen content (17.8 wt%) with nitrogen-containing groups and abundant basic sites. The hierarchical porous CN spheres have excellent CO2 capture properties with a capacity of 2.90 mmol/g at 25 °C and 0.97 mmol/g at 75 °C, superior to those of the pure carbon materials with analogous mesostructures. This can be mainly attributed to the abundant nitrogen-containing basic groups, hierarchical mesostructure, relatively high BET surface area and stable framework. Furthermore, the presence of a large number of micropores and small mesopores also enhance the CO2 capture performance, owing to the capillary condensation effect.  相似文献   

7.
Mesoporous carbons with bimodal rod-like pore structures and tunable pore sizes from 3.66 to 5.42 nm were for the first time obtained by employing SBA-15 as templates and raffinose as carbon precursors. Small angle X-ray diffraction, transmission electron microscopy, scanning electron microscopy, N2 sorption analysis, and Raman spectroscopy were used to determine the textural properties of the resulting materials. Bimodal frameworks with mesopores (4–5 nm) as well as macropores (125–130 nm) were achieved. The mesoporous carbons lost its ordered structure from the templates due to mesostructural shrinkage and collapse of mesopores, which resulted in partial duplicate of the template and pore-widening effect (meso to macropores). With the increasing of carbonization temperature from 500, 700 to 900 °C, the textural parameters such as specific surface areas, pore volumes, and mean pore diameters all increased significantly. In the temperature range studied, higher carbonization temperature would generate much more abundant porosity. The ratio of I D to I G (I D/I G) indicated a rather low crystallinity with the varying of aging temperature and the carbonization temperatures. The advantage of the procedure was that no acid or other chemical catalysts were involved during the infiltration and carbon formation process.  相似文献   

8.
Contamination of water resources by toxic metals and opportunistic pathogens remains a serious challenge. The development of nano-adsorbents with desired features to tackle this problem is a continuously evolving field. Here, magnetic mesoporous carbon nanospheres grafted by antimicrobial polyhexamethylene biguanidine (PHMB) are reported. Detailed mechanistic investigations reveal that the electrostatic stabilizer modified magnetic nanocore interfaced mesoporous shell can be programmatically regulated to tune the size and related morphological properties. The core–shell nano-adsorbent shows tailorable shell thickness (≈20–55 nm), high surface area (363.47 m2 g−1), pore volume (0.426 cm3 g−1), radially gradient pores (11.26 nm), and abundant biguanidine functionality. Importantly, the nano-adsorbent has high adsorption capacity for toxic thallium (Tl(I) ions (≈559 mg g−1), excellent disinfection against Staphylococcus aureus and Escherichia coli (>99.99% at 2 and 2.5 µg mL−1), ultrafast disinfection kinetics rate (>99.99% within ≈4 min), and remarkable regeneration capability when exposed to polluted water matrices. The Tl(I) removal is attributed to surface complexation and physical adsorption owing to open ended mesopores, while disinfection relies on contact of terminal biguanidines with phospholipid head groups of membrane. The significance of this work lies in bringing up effective synchronic water purification technology to combat pathogenic microorganisms and toxic metal.  相似文献   

9.
This study develops a novel strategy, based on block copolymer self‐assembly in solution, for preparing two‐dimensional (2D) graphene‐based mesoporous nanohybrids with well‐defined large pores of tunable sizes, by employing polystyrene‐block‐poly(ethylene oxide) (PS‐b‐PEO) spherical micelles as the pore‐creating template. The resultant 2D nanohybrids possess a sandwich‐like structure with Fe2O3 nanoparticle‐embedded mesoporous polypyrrole (PPy) monolayers grown on both sides of reduced graphene oxide (rGO) nanosheets (denoted as mPPy‐Fe2O3@rGO). Serving as supercapacitor electrode materials, the 2D ternary nanohybrids exhibit controllable capacitive performance depending on the pore size, with high capacitance (up to 1006 F/g at 1 A/g), good rate performance (750 F/g at 20 A/g) and excellent cycling stability. Furthermore, the pyrolysis of mPPy‐Fe2O3@rGO at 800 °C yields 2D sandwich‐like mesoporous nitrogen‐doped carbon/Fe3O4/rGO (mNC‐Fe3O4@rGO). The mNC‐Fe3O4@rGO nanohybrids with a mean pore size of 12 nm show excellent electrocatalytic activity as an oxygen reduction reaction (ORR) catalyst with a four‐electron transfer nature, a high half‐wave‐potential of +0.84 V and a limiting current density of 5.7 mA/cm2, which are well comparable with those of the best commercial Pt/C catalyst. This study takes advantage of block copolymer self‐assembly for the synthesis of 2D multifunctional mesoporous nanohybrids, and helps to understand the control of their structures and electrochemical performance.  相似文献   

10.
Hollow mesoporous carbon spheres (HMCSs) have been prepared by a simplified replication route from a solid silica core/mesoporous silica shell aluminosilicate (SCMS-Al) template, which was synthesized by directly incorporating aluminum species into the mesoporous framework during template synthesis. The size of HMCSs can be tuned between 80 and 470 nm by simply changing the diameters of SCMS-Al. The HMCSs have uniform mesopores with a narrow pore size distribution (3.4-4.1 nm), and high surface area, (890-1150 m2/g) and total pore volumes (0.75-1.15 cm3/g). The techniques of N2 sorption isotherms, TEM, EDX and SEM were used to characterize the as-synthesized spheres.  相似文献   

11.
Novel thermally stable and 2D mesoporous niobia phases were prepared by the evaporation induced self-assembly (EISA) with high surface areas (up to 211 m2/g). The pore size of these novel mesoporous niobium oxides was tuned in a wide range from 4.6 to 21 nm by increasing the aging temperature, aging time, and humidity of aging atmosphere. Mixtures of two nonionic surfactants, Pluronic P123 and Brij 35, were for the first time used to tune the pore structure of resultant mesoporous niobia phases which showed that the mesopore shape may be switched from cylindrical to ink-bottle. The niobia mesostructures obtained in this study were thermally stable up to 500 °C. These novel mesoporous niobium oxides with tunable pore sizes are highly promising as catalytic supports and a major component in the synthesis of porous Nb-containing mixed metal oxides, such as MoVTeNbO x catalysts for selective (amm)oxidation of propane.  相似文献   

12.
Functionalized ordered mesoporous silica materials are commonly investigated for applications such as drug release, sensing, and separation processes. Although, various homopolymer functionalized responsive mesopores are reported, little focus has been put on copolymers in mesopores. Mesoporous silica films are functionalized with responsive and orthogonally charged block‐co‐oligomers. Responsive 2‐dimethylamino)ethyl methacrylate)‐block‐2‐(methacryloyloxy)ethyl phosphate (DMAEMA‐b‐MEP) block‐co‐oligomers are introduced into mesoporous films using controlled photoiniferter initiated polymerization. This approach allows a very flexible charge composition design. The obtained block‐co‐oligomer functionalized mesopores show a complex gating behavior indicating a strong interplay between the different blocks emphasizing the strong influence of charge distribution inside mesopores on ionic pore accessibility. For example, in contrast to mesopores functionalized with zwitterionic polymers, DMAEMA‐b‐MEP block‐co‐oligomer functionalized mesopores, containing two oppositely charged blocks, do not show bipolar ion exclusion, demonstrating the influence of the chain architecture on mesopore accessibility. Furthermore, ligand binding–based selective gating is strongly influenced by this chain architecture as demonstrated by an expansion of pore accessibility states for block‐co‐oligomer functionalized mesopores as compared to the individual polyelectrolyte functionalization for calcium induced gating.  相似文献   

13.
1D carbon nanotubes have been widely applied in many fields, such as catalysis, sensing and energy storage. However, the long tunnel-like pores and relatively low specific surface area of carbon nanotubes often restrict their performance in certain applications. Herein, a dual-silica template-mediated method to prepare nitrogen-doped mesoporous carbon nanotubes (NMCTs) through co-depositing polydopamine (both carbon and nitrogen precursors) and silica nanoparticles (the porogen for mesopore formation) on a silica nanowire template is proposed. The obtained NMCTs have a hierarchical pore structure of large open mesopores and tubular macropores, a high specific surface area (1037 m2 g−1), and homogeneous nitrogen doping. The NMCT-45 (prepared at an interval time of 45 min) shows excellent performance in supercapacitor applications with a high capacitance (373.6 F g−1 at 1.0 A g−1), excellent rate capability, high energy density (11.6 W h kg−1 at a power density of 313 W kg−1), and outstanding cycling stability (98.2% capacity retention after 10 000 cycles at 10 A g−1). Owing to the unique tubular morphology, hierarchical porosity and homogeneous N-doping, the NMCT also has tremendous potential in electrochemical catalysis and sensing applications.  相似文献   

14.
Three-dimensional cage-like mesoporous FDU-12 materials with large tuneable pore sizes ranging from 9.9 to 15.6 nm were prepared by varying the synthesis temperature from 100 to 200 °C for the aging time of just 2 h using a tri-block copolymer F-127(EO106PO70EO106) as the surfactant and 1,3,5-trimethyl benzene as the swelling agent in an acidic condition. The mesoporous structure and textural features of FDU-12-HX (where H denotes the hydrothermal method and X denotes the synthesis temperature) samples were elucidated and probed using x-ray diffraction, N2 adsorption, 29Si magic angle spinning nuclear magnetic resonance, scanning electron microscopy and transmission electron microscopy. It has been demonstrated that the aging time can be significantly reduced from 72 to 2 h without affecting the structural order of the FDU-12 materials with a simple adjustment of the synthesis temperature from 100 to 200 °C. Among the materials prepared, the samples prepared at 200 °C had the highest pore volume and the largest pore diameter. Lysozyme adsorption experiments were conducted over FDU-12 samples prepared at different temperatures in order to understand their biomolecule adsorption capacity, where the FDU-12-HX samples displayed high adsorption performance of 29 μmol g−1 in spite of shortening the actual synthesis time from 72 to 2 h. Further, the influence of surface area, pore volume and pore diameter on the adsorption capacity of FDU-12-HX samples has been investigated and results are discussed in correlation with the textural parameters of the FDU-12-HX and other mesoporous adsorbents including SBA-15, MCM-41, KIT-5, KIT-6 and CMK-3.  相似文献   

15.
Core–shell magnetic porous microspheres have wide applications in drug delivery, catalysis and bioseparation, and so on. However, it is great challenge to controllably synthesize magnetic porous microspheres with uniform well‐aligned accessible large mesopores (>10 nm) which are highly desired for applications involving immobilization or adsorption of large guest molecules or nanoobjects. In this study, a facile and general amphiphilic block copolymer directed interfacial coassembly strategy is developed to synthesize core–shell magnetic mesoporous microspheres with a monolayer of mesoporous shell of different composition (FDUcs‐17D), such as core–shell magnetic mesoporous aluminosilicate (CS‐MMAS), silica (CS‐MMS), and zirconia‐silica (CS‐MMZS), open and large pores by employing polystyrene‐block‐poly (4‐vinylpyridine) (PS‐b‐P4VP) as an interface structure directing agent and aluminum acetylacetonate (Al(acac)3), zirconium acetylacetonate, and tetraethyl orthosilicate as shell precursors. The obtained CS‐MMAS microspheres possess magnetic core, perpendicular mesopores (20–32 nm) in the shell, high surface area (244.7 m2 g?1), and abundant acid sites (0.44 mmol g?1), and as a result, they exhibit superior performance in removal of organophosphorus pesticides (fenthion) with a fast adsorption dynamics and high adsorption capacity. CS‐MMAS microspheres loaded with Au nanoparticles (≈3.5 nm) behavior as a highly active heterogeneous nanocatalyst for N‐alkylation reaction for producing N‐phenylbenzylamine with a selectivity and yields of over 90% and good magnetic recyclability.  相似文献   

16.
李笑迎  白文静  陶凯  梁云霄 《材料导报》2018,32(10):1695-1700, 1715
以具有三维骨架结构的环氧树脂大孔聚合物为模板,制备具有毫米级尺寸的大孔/介孔多级孔SiO_2。应用SEM、MIP、FTIR和N_2吸附-脱附法对材料孔道结构和表面性质进行表征。采用吸附法固定褶皱假丝酵母脂肪酶(CRL),研究CRL初始浓度、pH值及固定化时间对脂肪酶固定化的影响,对比研究了游离脂肪酶和固定化脂肪酶的酶学性质。结果表明,大孔/介孔SiO_2具有三维连续贯通的大孔孔道,孔壁由连续的SiO_2纳米薄膜构筑而成且表面存在丰富的介孔,比表面积为75.1m~2/g,孔隙率为92.3%;在CRL浓度为0.6mg/mL、pH值为8.0、固定化时间为10h时,固定化酶酶活达到4 825U/g。与游离脂肪酶相比,固定化脂肪酶的pH稳定性、热稳定性和储存稳定性明显提高,连续使用8次后的酶活为初始酶活的68%。利用环氧树脂大孔聚合物模板制备的大孔/介孔多级孔SiO_2在固定化酶方面具有良好的应用前景。  相似文献   

17.
A novel degradation‐restructuring induced anisotropic epitaxial growth strategy is demonstrated for the synthesis of uniform 1D diblock and triblock silica mesoporous asymmetric nanorods with controllable rod length (50 nm to 2 µm) and very high surface area of 1200 m2 g?1. The asymmetric diblock mesoporous silica nanocomposites are composed of a 1D mesoporous organosilicate nanorod with highly ordered hexagonal mesostructure, and a closely connected dense SiO2 nanosphere located only on one side of the nanorods. Furthermore, the triblock mesoporous silica nanocomposites constituted by a cubic mesostructured nanocube, a nanosphere with radial mesopores, and a hexagonal mesostructured nanorod can also be fabricated with the anisotropic growth of mesopores. Owing to the ultrahigh surface area, unique 1D mesochannels, and functionality asymmetry, the obtained match‐like asymmetric Au‐NR@SiO2&EPMO (EPMO = ethane bridged periodic mesoporous organosilica) mesoporous nanorods can be used as an ideal nanocarrier for the near‐infrared photothermal triggered controllable releasing of drug molecules.  相似文献   

18.
The advantages of existing ordered mesoporous materials have not yet been fully realized, due to their limited accessibility of in-pore surface and long mass-diffusion length. A general, controllable, and scalable synthesis of a family of two-dimensional (2D) single-layer ordered mesoporous materials (SOMMs) with completely exposed mesopore channels, significantly improved mass diffusion, and diverse framework composition is reported here. The SOMMs are synthesized via a surface-limited cooperative assembly (SLCA) on water-removable substrates of inorganic salts (e.g., NaCl), combined with vacuum filtration. As a proof of concept, the obtained CeO2-based SOMMs show superior catalytic performance in CO oxidation with high conversion efficiency, ≈33 times higher than that of conventional bulk mesoporous CeO2. This SLCA is a promising approach for developing next-generation porous materials for various applications.  相似文献   

19.
Heteroatom-doped porous carbon materials with distinctive surface properties and capacitive behavior have been accepted as promising candidates for supercapacitor electrodes. Currently, the researches mainly focus on developing facile synthetic method and unveiling the structure-activity relationship to further elevate their capacitive performance. Here, the B, N co-doped porous carbon sheet (BN-PCS) is constructed by one-pot pyrolysis of agar in KCl/KHCO3 molten salt system. In this process, the urea acts as directing agent to guide the formation of 2D sheet morphology, and the decomposition of KHCO3 and boric acid creates rich micro- and mesopores in the carbon framework. The specific capacitance of optimized BN-PCS reaches 361.1 F g−1 at a current density of 0.5 A g−1 in an aqueous KOH electrolyte. Impressively, the fabricated symmetrical supercapacitor affords a maximum energy density of 43.5 Wh kg−1 at the power density of 375.0 W kg−1 in 1.0 mol L−1 TEABF4/AN electrolyte. It also achieves excellent long-term stability with capacitance retention of 91.1% and Columbic efficiency of 100% over 10 000 cycles. This study indicates one-pot molten salt method is effective in engineering advanced carbon materials for high-performance energy storage devices.  相似文献   

20.
Membrane separation technologies are of great interest in industrial processes such as water purification, gas separation, and materials synthesis. However, commercial filtration membranes have broad pore size distributions, leading to poor size cutoff properties. In this work, mesoporous silica thin membranes with uniform and large vertical mesochannels are synthesized via a simple biphase stratification growth method, which possess an intact structure over centimeter size, ultrathin thickness (≤50 nm), high surface areas (up to 1420 m2 g?1), and tunable pore sizes from ≈2.8 to 11.8 nm by adjusting the micelle parameters. The nanofilter devices based on the free‐standing mesoporous silica thin membranes show excellent performances in separating differently sized gold nanoparticles (>91.8%) and proteins (>93.1%) due to the uniform pore channels. This work paves a promising way to develop new membranes with well‐defined pore diameters for highly efficient nanosize‐based separation at the macroscale.  相似文献   

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