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1.
Molybdenum disulfide (MoS2) is a promising candidate as a high‐performing anode material for sodium‐ion batteries (SIBs) due to its large interlayer spacing. However, it suffers from continued capacity fading. This problem could be overcome by hybridizing MoS2 with nanostructured carbon‐based materials, but it is quite challenging. Herein, we demonstrate a single‐step strategy for the preparation of MoS2 coupled with ordered mesoporous carbon nitride using a nanotemplating approach which involves the pyrolysis of phosphomolybdic acid hydrate (PMA), dithiooxamide (DTO) and 5‐amino‐1H‐tetrazole (5‐ATTZ) together in the porous channels of 3D mesoporous silica template. The sulfidation to MoS2, polymerization to carbon nitride (CN) and their hybridization occur simultaneously within a mesoporous silica template during a calcination process. The CN/MoS2 hybrid prepared by this unique approach is highly pure and exhibits good crystallinity as well as delivers excellent performance for SIBs with specific capacities of 605 and 431 mAhg?1 at current densities of 100 and 1000 mAg?1, respectively, for SIBs.  相似文献   

2.
Highly ordered 3D‐hexagonal mesoporous silica HMS‐3 and its vinyl‐ and 3‐chloropropyl‐functionalized analogues HMS‐4 and ‐5, respectively, are synthesized under strongly alkaline conditions at 277 K. Tetraethyl orthosilicate, vinyltrimethoxysilane, and 3‐chloropropyltrimethoxysilane are used as silica sources, and cetyltrimethylammonium bromide as the structure‐directing agent. The 3D‐hexagonal pore structures of HMS‐3, 4‐, and ‐5 were confirmed by powder XRD and high‐resolution TEM studies. Brunauer–Emmett–Teller surface areas of these materials are 1353, 1211, and 603 m2 g?1 for HMS‐3, ‐4, and ‐5, respectively. Among these materials, vinyl‐functionalized mesoporous material HMS‐4 adsorbs the highest CO2 (5.5 mmol g?1, 24.3 wt %) under 3 bar pressure at 273 K. The 3D‐hexagonal pore openings, very high surface area, and cagelike mesopores as well as organic functionalization could be responsible for very high CO2 uptakes of these materials compared to other related mesoporous silica‐based materials.  相似文献   

3.
《Electroanalysis》2018,30(3):436-444
Electrocatalysts perform a key role in increasing efficiency of the oxygen reduction reaction (ORR) and as a result, efforts have been made by the scientific community to develop novel and cheap materials that have the capability to exhibit low ORR overpotentials and allow the reaction to occur via a 4 electron pathway, thereby mimicking as close as possible to traditionally utilised platinum. In that context, two different types of carbon nanodots (CNDs) with amide (CND‐CONH2) and carboxylic (CND‐COOH) surface groups, have herein been fabricated and shown to exhibit excellent electrocatalytic activity towards the ORR in acid and basic media (0.1 M H2SO4 and 0.1 M KOH). CND surface modified carbon screen‐printed electrodes allow for a facile electrode modification and enabling the study of the CNDs electrocatalytic activity towards the ORR. CND‐COOH modified SPEs are found to exhibit improved ORR peak current and reduced overpotential by 21.9 % and 26.3 %, respectively compared to bare/unmodified SPEs. Additionally, 424 μg cm−2 CND‐COOH modified SPEs in oxygenated 0.1 M KOH are found to facilitate the ORR via a near optimal 4 (3.8) electron ORR pathway. The CNDs also exhibited excellent long‐term stability and tolerance with no degradation being observed in the achievable current with the ORR current returning to the baseline level within 100 seconds of exposure to a 1.5 M solution of methanol. In summary, the CND‐COOH could be utilised as a cathodic electrode for PEMFCs offering greater stability than a commercial Pt electrode.  相似文献   

4.
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.  相似文献   

5.
Prussian blue and its analogues (PBAs) have been recognized as one of the most promising cathode materials for room‐temperature sodium‐ion batteries (SIBs). Herein, we report high crystalline and Na‐rich Prussian white Na2CoFe(CN)6 nanocubes synthesized by an optimized and facile co‐precipitation method. The influence of crystallinity and sodium content on the electrochemical properties was systematically investigated. The optimized Na2CoFe(CN)6 nanocubes exhibited an initial capacity of 151 mA h g?1, which is close to its theoretical capacity (170 mA h g?1). Meanwhile, the Na2CoFe(CN)6 cathode demonstrated an outstanding long‐term cycle performance, retaining 78 % of its initial capacity after 500 cycles. Furthermore, the Na2CoFe(CN)6 Prussian white nanocubes also achieved a superior rate capability (115 mA h g?1 at 400 mA g?1, 92 mA h g?1 at 800 mA g?1). The enhanced performances could be attributed to the robust crystal structure and rapid transport of Na ions through large channels in the open‐framework. Most noteworthy, the as‐prepared Na2CoFe(CN)6 nanocubes are not only low‐cost in raw materials but also contain a rich sodium content (1.87 Na ions per lattice unit cell), which will be favorable for full cell fabrication and large‐scale electric storage applications.  相似文献   

6.
Bimetallic three‐dimensional amorphous mesoporous materials, Al‐Zr‐TUD‐1 materials, were synthesised by using a surfactant‐free, one‐pot procedure employing triethanolamine (TEA) as a complexing reagent. The amount of aluminium and zirconium was varied in order to study the effect of these metals on the Brønsted and Lewis acidity, as well as on the resulting catalytic activity of the material. The materials were characterised by various techniques, including elemental analysis, X‐ray diffraction, high‐resolution TEM, N2 physisorption, temperature‐programmed desorption (TPD) of NH3, and 27Al MAS NMR, XPS and FT‐IR spectroscopy using pyridine and CO as probe molecules. Al‐Zr‐TUD‐1 materials are mesoporous with surface areas ranging from 700–900 m2 g?1, an average pore size of around 4 nm and a pore volume of around 0.70 cm3 g?1. The synthesised Al‐Zr‐TUD‐1 materials were tested as catalyst materials in the Lewis acid catalysed Meerwein–Ponndorf–Verley reduction of 4‐tert‐butylcyclohexanone, the intermolecular Prins synthesis of nopol and in the intramolecular Prins cyclisation of citronellal. Although Al‐Zr‐TUD‐1 catalysts possess a lower amount of acid sites than their monometallic counterparts, according to TPD of NH3, these materials outperformed those of the monometallic Al‐TUD‐1 as well as Zr‐TUD‐1 in the Prins cyclisation of citronellal. This proves the existence of synergistic properties of Al‐Zr‐TUD‐1. Due to the intramolecular nature of the Prins cyclisation of citronellal, the hydrophilic surface of the catalyst as well as the presence of both Brønsted and Lewis acid sites synergy could be obtained with bimetallic Al‐Zr‐TUD‐1. Besides spectroscopic investigation of the active sites of the catalyst material a thorough testing of the catalyst in different types of reactions is crucial in identifying its specific active sites.  相似文献   

7.
Mesoporous TiO2 microspheres with high specific surface areas were synthesized by means of a facile one‐step microwave hydrothermal process without using any template. The mesoporous materials were rapidly achieved using TiCl4, urea and ammonium sulphate at comparatively low microwave power (400 W) for 8 min irradiation. The morphology and microstructure of the as‐prepared products were characterized by field emission scanning electron microscopy (FESEM), X‐ray diffraction (XRD), transmission electron microscopy (TEM) and Brunauer‐Emmett‐Teller (BET) surface area analysis. Structural characterization indicates that the TiO2 microspheres display mesoporous structure. The average pore sizes and BET surface areas of the spheres were 5.3 nm and 222 m2g?1, respectively. The mesoporous nanocrystals synthesized at 160 °C for 8 min were then used to prepare the photoanode for dye sensitized solar cells (DSSCs). A high power conversion efficiency of 5.72% was achieved from the mesoporous TiO2 based photoanode, representing about 25.7% improvement over the efficiency of P25 photoanode.  相似文献   

8.
The CN‐15‐x series materials with different doses of SBA‐15 template and the CN‐y‐2.0 series materials with different hard templates were prepared by the hard template method with hexamethylenetetramine as the carbon and nitrogen source. The obtained mesoporous carbon materials were characterized by X‐ray diffraction (XRD), N2 adsorption–desorption, transmission electron microscopy (TEM), Raman spectroscopy, and X‐ray photoelectron spectroscopy (XPS). The catalytic performance of propane oxidative dehydrogenation was determined. The characterization results indicate that the catalytic activity of CN‐15‐2.0 with a bipartite hexagonal ordered structure was higher than those of the other materials. The conversion of propane was 22.98%, and the selectivity toward propylene was 41.70%.  相似文献   

9.
A mesoporous flake‐like manganese‐cobalt composite oxide (MnCo2O4) is synthesized successfully through the hydrothermal method. The crystalline phase and morphology of the materials are characterized by X‐ray diffraction, field‐emission scanning electron microscopy, transmission electron microscopy, and Brunauer–Emmett–Teller methods. The flake‐like MnCo2O4 is evaluated as the anode material for lithium‐ion batteries. Owing to its mesoporous nature, it exhibits a high reversible capacity of 1066 mA h g?1, good rate capability, and superior cycling stability. As an electrode material for supercapacitors, the flake‐like MnCo2O4 also demonstrates a high supercapacitance of 1487 F g?1 at a current density of 1 A g?1, and an exceptional cycling performance over 2000 charge/discharge cycles.  相似文献   

10.
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.  相似文献   

11.
Silicon‐mediated fluoride abstraction is demonstrated as a means of generating the first fluorido‐cyanido transition metal complexes. This new synthetic approach is exemplified by the synthesis and characterization of the heteroleptic complexes, trans‐[MIVF4(CN)2]2? (M=Re, Os), obtained from their homoleptic [MIVF6]2? parents. As shown by combined high‐field electron paramagnetic resonance spectroscopy and magnetization measurements, the partial substitution of fluoride by cyanide ligands leads to a marked increase in the magnetic anisotropy of trans‐[ReF4(CN)2]2? as compared to [ReF6]2?, reflecting the severe departure from an ideal octahedral (Oh point group) ligand field. This methodology paves the way toward the realization of new heteroleptic transition metal complexes that may be used as highly anisotropic building‐blocks for the design of high‐performance molecule‐based magnetic materials.  相似文献   

12.
Cubic mesoporous titanium phosphonate materials with bridged organic groups inside the framework were synthesized by means of a one‐pot hydrothermal autoclaving process, with the assistance of cationic surfactant cetyltrimethylammonium bromide. 1‐Hydroxyethylidene‐1,1‐diphosphonic acid was used as the coupling molecule. A typical cubic mesophase with surface area of 1052 m2 g?1 and pore size of 2.6 nm was confirmed by XRD, TEM, and N2 sorption analysis. The organophosphonate groups were homogeneously incorporated in the network of the mesoporous solids, as revealed by FTIR and magic‐angle spinning (MAS) NMR spectroscopy, and thermogravimetry and differential scanning calorimetry (TG‐DSC) measurements. The synthesized hydroxyethylidene‐bridged cubic mesoporous titanium phosphonates proved to be thermally stable up to 350 °C, with a well‐preserved hybrid framework and cubic mesoporous architecture. The obtained cubic mesophase could be transformed into a hexagonal mesophase by simply adjusting the molar ratios of the added raw materials, namely, a Ti/P molar ratio of 1:4 and a CTAB/Ti molar ratio of 1.9–2.3 for the cubic phase and Ti/P molar ratio of 3:4 and CTAB/Ti molar ratio of 0.1–0.4 for the hexagonal phase. The cubic hybrid materials could be used as efficient photocatalysts for the photodegradation of rhodamine B. Moreover, they were also used for adsorption of CO2 and heavy metal ions and exhibited a significant capture amount of around 1.0 mmol g?1 for CO2 molecules at 35 °C and high adsorption capacity of 28.5 μmol g?1 for Cu2+ ions with good reusability, which demonstrated their promising potential in environmental remediation.  相似文献   

13.
The synthesis of new random poly(2,7‐fluorenylene‐vinylene)s was achieved by a Suzuki–Heck cascade polymerization reaction. The poly(fluorenylene‐vinylene) base structure was modified by the regio‐random incorporation of 1‐cyano‐2,5‐phenylene as electron withdrawing unit ( CN‐PFV1 ) and its properties were compared with terpolymers also embodying 1,4‐dioctyloxy‐2,5‐phenylene ( CN‐PFV2 ) or 3,6‐N‐octylcarbazole ( CN‐PFV3 ) as electron‐donating moieties. Thermal analysis revealed a high thermal stability (Td > 389 °C) and the absence of glass transitions for all polymers. Cyclic voltammetry indicated a high electron affinity of the materials (2.96–3.21 eV) attributed to the presence of the cyano‐containing comonomer. In dilute solutions, the copolymers showed a broad green fluorescence with quantum yields ranging from 0.42 to 0.79, while in the solid state, a relatively narrow emission centered at ~ 560 nm, governed by the low‐energy segments within the π‐conjugated backbone, was observed. The electroluminescence properties of the materials were tested in OLED devices of ITO/PEDOT‐PSS/ CN‐PFV1‐3 /Ca/Al or ITO/PEDOT‐PSS/ CN‐PFV1‐3 /Alq3/Ca/Al configurations, showing a bright green‐yellow emission that, in the case of CN‐PFV2 , reached 1403 cd/m2 with efficiencies as high as 0.13 cd/A. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6051–6063, 2008  相似文献   

14.
Highly ordered mesoporous Co3O4 nanostructures were prepared using KIT‐6 and SBA‐15 silica as hard templates. The structures were confirmed by small angle X‐ray diffraction, high resolution transmission electron microscopy, and N2 adsorption–desorption isotherm analysis. Both KIT‐6 cubic and SBA‐15 hexagonal mesoporous Co3O4 samples exhibited a low Néel temperature and bulk antiferromagnetic coupling due to geometric confinement of antiferromagnetic order within the nanoparticles. Mesoporous Co3O4 electrode materials have demonstrated the high lithium storage capacity of more than 1200 mAh g?1 with an excellent cycle life. They also exhibited a high specific capacitance of 370 F g?1 as electrodes in supercapacitors.  相似文献   

15.
A meostructured WO3/C composite with crystalline framework and high electric conductivity has been synthesized by a new in situ carbonization–replication route using the block copolymer (poly(ethylene glycol)‐block‐poly(propylene glycol)‐block‐poly(ethylene glycol)) present in situ in the pore channels of mesoporous silica template as carbon source. X‐ray diffraction, X‐ray photoelectron spectroscopy, transmission electron microscopy, thermogravimetry differential thermal analysis, and N2 adsorption techniques were adopted for the structural characterization. Cyclic voltammetry, chronoamperometry, and single‐cell test for hydrogen electrochemical oxidation were adopted to characterize the electrochemical activities of the mesoporous WO3/C composite. The carbon content and consequent electric conductivity of these high‐surface‐area (108–130 m2 g?1) mesostructured WO3/C composite materials can be tuned by variation of the duration of heat treatment, and the composites exhibited high and stable electrochemical catalytic activity. The single‐cell test results indicated that the mesostructured WO3/C composites showed clear electrochemical catalytic activity toward hydrogen oxidation at 25 °C, which makes them potential non‐precious‐metal anode catalysts in proton exchange membrane fuel cell.  相似文献   

16.
《化学:亚洲杂志》2017,12(1):36-40
N‐doped mesoporous carbon‐capped MoO2 nanobelts (designated as MoO2@NC) were synthesized and applied to lithium‐ion storage. Owing to the stable core–shell structural framework and conductive mesoporous carbon matrix, the as‐prepared MoO2@NC shows a high specific capacity of around 700 mA h g−1 at a current of 0.5 A g−1, excellent cycling stability up to 100 cycles, and superior rate performance. The N‐doped mesoporous carbon can greatly improve the conductivity and provide uninhibited conducting pathways for fast charge transfer and transport. Moreover, the core–shell structure improved the structural integrity, leading to a high stability during the cycling process. All of these merits make the MoO2@NC to be a suitable and promising material for lithium ion battery.  相似文献   

17.
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.  相似文献   

18.
1,3‐Diphenyl‐1,3‐propanepione (DBM)‐functionalized SBA‐15 and SBA‐16 mesoporous hybrid materials (DBM‐SBA‐15 and DBM‐SBA‐16) are synthesized by co‐condensation of modified 1,3‐diphenyl‐1,3‐propanepione (DBM‐Si) and tetraethoxysilane (TEOS) in the presence of Pluronic P123 and Pluronic F127 as a template, respectively. The as‐synthesized mesoporous hybrid material DBM‐SBA‐15 and DBM‐SBA‐16 are used as the first precursor, and the second precursor poly(methylacrylic acid) (PMAA) is synthesized through the addition polymerization reaction of the monomer methacrylic acid. These precursors then coordinate to lanthanide ions simultaneously, and the final mesoporous polymeric hybrid materials Ln(DBM‐SBA‐15)3PMAA and Ln(DBM‐SBA‐16)3PMAA (Ln=Eu, Tb) are obtained by a sol‐gel process. For comparison, binary lanthanide SBA‐15 and SBA‐16 mesoporous hybrid materials (denoted as Ln(DBM‐SBA‐15)3 and Ln(DBM‐SBA‐16)3) are also synthesized. The luminescence properties of these resulting materials are characterized in detail, and the results reveal that ternary lanthanide mesoporous polymeric hybrid materials present stronger luminescence intensities, longer lifetimes, and higher luminescence quantum efficiencies than the binary lanthanide mesoporous hybrid materials. This indicates that the introduction of the organic polymer chain is a benefit for the luminescence properties of the overall hybrid system. In addition, the SBA‐15 mesoporous hybrids show an overall increase in luminescence lifetime and quantum efficiency compared with SBA‐16 mesoporous hybrids, indicating that SBA‐15 is a better host material for the lanthanide complex than mesoporous silica SBA‐16.  相似文献   

19.
In this work, we aimed to improve the antibacterial activity of sulfamethoxazole (SMX) via its inclusion in a newly synthesized nanocomposite composed of CuFe2O4 nanoparticles and poly(vinyl alcohol)/silica‐based mesoporous materials. Characterization of this formulation using different techniques confirmed the correct synthesis and showed that this mesoporous nanocomposite had an amorphous structure with relatively high surface area of 1,620.7 m2 g?1 and mean pore diameter of 1.6576 nm. Zeta potential of the formulation was obtained to be zero which led to its higher bioavailability in comparison to pure SMX with negative zeta potential. Antibacterial property of the prepared formulation against Staphylococcus aureus and Escherichia coli was evaluated. Minimum inhibitory concentration of the SMX‐loaded mesoporous nanocomposite was considerably lower than those of pure SMX, indicating the efficient function of the mesoporous material as a delivery system. Kinetics of SMX release was also studied using zero‐order, first‐order, Higuchi, and Korsmeyer–Peppas kinetics models. According to the obtained results, the release kinetics was found to obey zero‐order model. So the possibility of sustained release of SMX from the synthesized carrier may be suggested.  相似文献   

20.
A hierarchical macro‐/mesoporous Ce0.49Zr0.37Bi0.14O1.93 solid‐solution network has been synthesized on a large scale by means of a simple and general polymerization–carbonization–oxidation synthetic route. The as‐prepared product has been characterized by SEM, XRD, TEM, BET surface area measurement, UV/Vis diffuse‐reflectance spectroscopy, energy‐dispersive X‐ray spectroscopy (EDS), and photoelectrochemistry measurements. The photocatalytic activity of the product has been demonstrated through the photocatalytic degradation of methyl orange. Structural characterization has indicated that the hierarchical macro‐/mesoporous solid‐solution network not only contains numerous macropores, but also possesses an interior mesoporous structure. The mesopore size and BET surface area of the network have been measured as 2–25 nm and 140.5 m2 g?1, respectively. The hierarchical macro‐/mesoporous solid‐solution network with open and accessible pores was found to be well‐preserved after calcination at 800 °C, indicating especially high thermal stability. Due to its high specific surface area, the synergistic effect of the coupling of macropores and mesopores, and its high crystallinity, the Ce0.49Zr0.37Bi0.14O1.93 solid‐solution material shows a strong structure‐induced enhancement of visible‐light harvest and exhibits significantly improved visible‐light photocatalytic activity in the photodegradation of methyl orange compared with those of its other forms, such as mesoporous hollow spheres and bulk particles.  相似文献   

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