共查询到20条相似文献,搜索用时 15 毫秒
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在乙醇/水的混合溶液中,采用聚乙烯吡咯烷酮(PVP)为分散剂,偶氮二异丁腈(AIBN)为引发剂,通过分散聚合法制备出聚苯乙烯(PS)微球。然后以微球为模板,PS粒子作为核,SiO_2作为壳,在600℃时经过热分解得到SiO_2空心球。通过热分析仪、扫描电子显微镜对制得的空心球进行了表征和分析,并讨论其影响因素。 相似文献
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Thiourea formaldehyde resin has been condensation-polymerized in the polypyrrole hollow spheres suspension to obtain TF/PPy. Then, TF/PPy has been carbonized at 750 °C to acquire CTF/PPy composites. Scanning electron microscope and transmission electron microscope images were used to observe the morphology of the samples, TGA, XRD, Raman, XPS, and BET were used to analyze the structure of the materials. The results show PPy was blended with the TF resin, and the obtained CTF/PPy exhibited improved supercapacitive performances compared with CTF. The specific capacitance of CTF/PPy is 226.8 F g−1 at the current density of 1 A g−1 according to GCD curves, much higher than that of CTF. More interestingly, the cycling retention of CTF/PPy electrode at the current density of 10 A g−1 is up to 120.2% after 10 000 cycles. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47816. 相似文献
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Xiang-Hui Yu Jin-Long Yi Ru-Liang Zhang Feng-Yun Wang Lei Liu 《Frontiers of Chemical Science and Engineering》2021,15(6):1380
Hollow carbon spheres have garnered great interest owing to their high surface area, large surface-to-volume ratio and reduced transmission lengths. Herein, we overview hollow carbon sphere-based materials and their noble metal-free hybrids in catalysis. Firstly, we summarize the key fabrication techniques for various kinds of hollow carbon spheres, with a particular emphasis on controlling pore structure and surface morphology, and then heterogeneous doping as well as their metal-free/containing hybrids are presented; next, possible applications for non-noble metal/hollow carbon sphere hybrids in the area of energy-related catalysis, including oxygen reduction reaction, hydrogen evolution reaction, oxygen evolution reaction, water splitting, rechargeable Zn-air batteries and pollutant degradation are discussed; finally, we introduce the various challenges and opportunities offered by hollow carbon spheres from the perspective of synthesis and catalysis. 相似文献
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Junjie Yang Xiaoyan Zhang Wenhao Li Jinlong Yang 《Journal of the American Ceramic Society》2023,106(6):3884-3894
We here propose a simple, facile, and effective method to prepare submicron mullite hollow spheres templated from Pickering emulsions. Dual-phase sol consisted of boehmite and silica nanoparticles decorated by pentanoate ion could assemble at water/oil interface irreversibly to form photosensitive Pickering emulsions. The droplets of emulsions could be separated by dilution and formed by photopolymerization to gain hybrid microspheres, which could completely transform to mullite hollow microspheres via binder removal and sintering. It is found that the prepared hollow microspheres possess intact morphology, favorable sphericity, large cavity volume, and bulk density of 0.356 g/cm3. Importantly, the average diameter of mullite hollow spheres obtained via this method could be as low as 0.33–2.31 μm. This steady method is efficient and suitable for various types of inorganic particles, providing an innovative perspective for preparing fine hollow spheres applicable for filtration, drug loading as well as energy storage areas. 相似文献
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We have evaluated the optical properties of close‐packed and non close‐packed colloidal crystalline arrays made of hollow polystyrene spheres. Close‐packed colloidal crystalline arrays were fabricated by simple evaporation of dispersions, whereas nonclose‐packed colloidal crystalline arrays were fabricated by exploiting electrostatic interactions between the spheres in aqueous dispersion. Optical properties of the arrays were estimated from angle‐resolved reflection spectra. The Bragg diffraction peak of the colloidal crystalline array made of hollow spheres was of shorter wavelength than in the case of solid spheres, not only for the close‐packed array but also for the nonclose‐packed array. These shifts were caused by a decrease in the effective refractive index neff with decreasing particle refractive index. We have found that this relationship could be explained by the simple equation neff = nparticle?+ nsolvent (1 ? ?), where ? is the volume fraction of the particles, for both close‐packed and non close‐packed arrays. The current work suggests new possibilities for the creation of advanced colloidal crystals. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2364–2368, 2007 相似文献
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In this paper, we propose a general template synthesis approach towards composite hollow spheres using sulfonated polystyrene gel hollow spheres. The gel hollow spheres are highly crosslinked to well preserve the spherical contour during template synthesis. It is important that the gel shell is infiltrative to many species to allow their further growth therein by specific interaction. The grown materials are well distributed thorough the whole shell forming composite shells. This method is general, which is proved by the growth of many representative materials for example metal Pd nanoparticles, magnetite Fe3O4 nanocrystallites, conducting polyaniline, and inorganic titania and silica. It is found that mesoporous inorganic shells are obtained after the template gel is calcined. This concept can be applied to other gel shells and grown materials expecting a new family of composite hollow spheres. 相似文献
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Xiaojing ZHANG Weixin ZHANG Zeheng YANG Zhao ZHANG 《Frontiers of Chemical Science and Engineering》2012,6(3):246
A solvothermal method has been successfully used to prepare nanostructured hydroxyapatite (HA) hollow spheres with average diameters of about 500 nm and shell thicknesses of about 100 nm in a glycerin/water mixed solvent. Transmission electron microscopy (TEM) and field-emission scanning electron microscopy (FESEM) images show that the shells of the HA hollow spheres are actually composed of nanosheets with thicknesses of about 10 nm. By tuning the glycerin/water volume ratio, two other kinds of HA solid spheres with average diameters of about 6 or 20 μm were assembled from nanoflakes. The properties of the different kinds of spheres as drug delivery carriers were evaluated. Ibuprofen (IBU) was chosen as the model drug to load into the HA samples. The nanostructured HA samples showed a slow and sustained release of IBU. The HA hollow spheres exhibited a higher drug loading capacity and more favorable release properties than the HA solid spheres and thus are very promising for controlled drug release applications. 相似文献
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《Ceramics International》2016,42(7):8409-8412
Ceramic hollow spheres were produced by a sacrificial template technique with subsequent sintering under temperatures ranging from 1100 °C to 1250 °C. The effect of the sintering temperature on the structure of the ceramic hollow spheres was investigated by optical and scanning electron microscopy, and a gas adsorption method. The results show that the structure of the ceramic hollow spheres can be controlled, with the retention of the hollow spherical shape, by variation of the sintering temperature. Increase of the sintering temperature from 1100 °C to 1250 °C decreased the outer diameter of the ceramic hollow spheres by 14 percent, the shell thickness by 18 percent, and the void area ratio of the shell surface by 9.2 times; both of the specific surface area and the total pore volume of ceramic hollow spheres decreased by 60 percent. 相似文献
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Eccentric double-shelled hollow polyethylacrylate (PEA)/polystyrene (PS) crosslinked composite spheres were synthesized by phase separation during swelling polymerization of their mother polymer hollow spheres. The group -NH2 was introduced within the network by ammonization of PEA. Other materials for example silica could be favorably grown within the gel network by a sol-gel process. The polymer/silica hollow spheres gave the corresponding derivative hollow spheres with varied composition including SiO2/carbon, carbon and β-SiC, with the eccentric double-shelled morphology retained. 相似文献
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Karolina Wilgosz Xuecheng Chen Krzysztof Kierzek Jacek Machnikowski Ryszard J Kalenczuk Ewa Mijowska 《Nanoscale research letters》2012,7(1):269
Mesoporous carbon spheres (MCS) have been fabricated from structured mesoporous silica sphere using chemical vapor deposition (CVD) with ethylene as a carbon feedstock. The mesoporous carbon spheres have a high specific surface area of 666.8 m2/g and good electrochemical properties. The mechanism of formation mesoporous carbon spheres (carbon spheres) is investigated. The important thing is a surfactant hexadecyl trimethyl ammonium bromide (CTAB), which accelerates the process of carbon deposition. An additional advantage of this surfactant is an increase the yield of product. These mesoporous carbon spheres, which have good electrochemical properties is suitable for supercapacitors. 相似文献
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A facile and general one-step approach is presented to synthesize hollow spheres with varied composition by an aerosol-assisted solvent evaporation process. The monomer of ethyl-2-cyanoacrylatemide contained in the aerosol droplets can form an outer shell by a fast polymerization around the droplets. Materials inside the droplets further grow inwardly against onto the interior surface of the first shell forming another shell forming composite hollow spheres. The hollow spheres are derived by dissolution of the outer shell, therefore the intact shell can be well preserved. Many approaches can be exploited forming the second shell for example sol-gel process of oligomers and phase separation from polymer solutions. Microstructure of the hollow spheres can be tuned from smooth to porous. The methodology is general. 相似文献
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A novel route to hollow and solid carbon spheres 总被引:2,自引:0,他引:2
Liqiang Xu 《Carbon》2005,43(5):1090-1092
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Au/poly(o‐toluidine) (POT) core/shell composite spheres have been successfully fabricated by chemical polymerization route in aqueous solution without the aid of surfactant or functional acids using HAuCl4 as the oxidant. By altering the concentration of oxidant, the amount of Au nanoparticles inside each POT sphere can be tuned from tens to one. Moreover, uniform POT hollow spheres with one opening in each polymer surface can be obtained under extremely low concentration of oxidant. The chemical structures of Au/POT composites were confirmed by Fourier transform infrared (FTIR), UV‐vis, and X‐ray diffraction (XRD) spectroscopies. Moreover, the formation mechanisms of Au/POT core/shell composites and POT hollow spheres were also discussed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
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Hai-jing Liu 《Electrochimica acta》2008,53(22):6497-6503
A new type of nano-sized cobalt oxide compounded with mesoporous carbon spheres (MCS) as negative electrode material for lithium-ion batteries was synthesized. The composite containing about 20 wt.% cobalt oxide exhibits a reversible capacity of 703 mAh/g at a constant current density of 70 mA/g between 0.01 and 3.0 V (vs. Li+/Li), and remains a capacity retention of 77% after the 30th cycle. The improvement could be attributed to that the MCS had a good electronic conductivity and severed as dispersing medium to prevent cobalt oxide nanoparticles from aggregating, and the mesopores (cobalt oxide not fully occupied) can provide the enough space to buffer the volume change during the Li-ion insertion and extraction reactions in cobalt oxide nanoparticles. 相似文献