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1.
In this study,we have established a facile method to synthesize functional hollow carbon spheres with large hollow interior,which can act as active colloidal catalysts.The method includes the following steps:first,hollow polymer spheres with large hollow interior were prepared using sodium oleate as the hollow core generator,and 2,4-dihydroxybenzoic acid and hexamethylene tetramine(HMT) as the polymer precursors under hydrothermal conditions;Fe 3+ or Ag + cations were then introduced into the as-prepared hollow polymer spheres through the carboxyl groups;finally,the hollow polymer spheres can be pseudomorphically converted to hollow carbon spheres during pyrolysis process,meanwhile iron or silver nanoparticles can also be formed in the carbon shell simultaneously.The structures of the obtained functional hollow carbon spheres were characterized by TEM,XRD,and TG.As an example,Ag-doped hollow carbon spheres were used as colloid catalysts which showed high catalytic activity in 4-nitrophenol reduction reaction. 相似文献
2.
A general protocol to coat titania shell on carbon-based composite cores using carbon as coupling agent 总被引:2,自引:0,他引:2
We present herein a general protocol to coat titania shell on carbon-based composite cores via the hydrolysis of titanium tetrabutoxide in a mixed solvent with the catalysis of ammonia. As coupling agent, their carbonaceous component can adsorb counter-charged NH4+, and then the negatively charged ≡TiO− species are adsorbed via electrostatic interaction to form TiO2 shell. Various carbon-based cores with different functional components, such as Ag/C core/shell spheres, Ag/C nanocables, as well as magnetic (C-Fe3O4) hollow spheres can be coated with titania shell to form corresponding core/shell composites. Their optical or magnetic property is also investigated. Finally, anatase-phase titania shell with rough surface can be generated via hydrothermal treatment of aforementioned titania coated composites, which can further introduce the properties of anatase-phase titania to the composites. 相似文献
3.
Uniform hollow Au@TiO2 core shell spheres with moveable Au nanoparticles were synthesized based on templating against Au@carbon spheres. The diameter of the shell of the Au@TiO2 spheres could be controlled by adjusting the Ti(OC4H9)4 hydrolyzing reaction time or the ratio of Ti(OC4H9)4 to Au@carbon spheres, and the shell thickness of the core-shell spheres can be varied from 25 nm to 40 nm. As prepared hollow Au@TiO2 core-shell spheres display enhanced photocatalytic activity in the initial stage of photocatalytic degradation of methylene blue compared with pure hollow TiO2 spheres and the commercial photocatalyst TiO2(P-25). 相似文献
4.
Hui Liu Hongliang Li Zhaolong Ding Aiping Fu Hongyan wang Peizhi Guo Jianqiang Yu Cunguo Wang Xiu Song Zhao 《Journal of Cluster Science》2012,23(2):273-285
Using the surface charged and acid dissolvable melamine formaldehyde (MF) microspheres as sacrificial hard templates, silica coated MF core?Cshell composite microspheres, denoted as MF@SiO2, were synthesized via a surfactant-assisted sol?Cgel process by using tetraethyl orthosilicate (TEOS) as silica source. Hollow SiO2 spheres with mesoporous shells were then obtained after selective removal of the MF cores and the pore directing surfactant by hydrochloric acid etching or calcinations in air. Interesting shrinkage phenomena were observed in both the hollow products derived from hydrochloric acid etching and calcinations. The influence of the ratio of MF sphere to TEOS and the removal method of the MF core on the size of the hollow spheres, the shell thickness and the shell surface roughness have been studied. The composition, the thermal stability, the morphology, the surface area and pore size distribution, the wall thickness and adsorption properties of the hollow spheres derived from hydrochloric acid etching and calcinations were also investigated and compared based on the FTIR, SEM, TEM, TGA, Nitrogen adsorption?Cdesorption and spectrophotometer techniques or measurements. 相似文献
5.
Synthesis of Hollow Mesoporous TiO2 Microspheres with Single and Double Au Nanoparticle Layers for Enhanced Visible‐Light Photocatalysis
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Dr. Zia Ur Rahman Dr. Ning Wei Dr. Yange Feng Dr. Xiaolong Zhang Prof. Daoai Wang 《化学:亚洲杂志》2018,13(4):432-439
A facile method was used to prepare hollow mesoporous TiO2 and Au@TiO2 spheres using polystyrene (PS) templates. Au nanoparticles (NPs) were simultaneously synthesized and attached on the surface of PS spheres by reducing AuCl4? ions using sodium citrate which resulted in the uniform deposition of Au NPs. The outer coating of titania via sol‐gel produced PS@Au@TiO2 core–shell spheres. Removing the templates from these core–shell spheres through calcination produced hollow mesoporous and crystalline Au@TiO2 spheres with Au NPs inside the TiO2 shell in a single step. Anatase spheres with double Au NPs layers, one inside and another outside of TiO2 shell, were also prepared. Different characterization techniques indicated the hollow mesoporous and crystalline morphology of the prepared spheres with Au NPs. Hollow anatase spheres with Au NPs indicated enhanced harvesting of visible light and therefore demonstrated efficient catalytic activity toward the degradation of organic dyes under the irradiation of visible light as compared to bare TiO2 spheres. 相似文献
6.
Prof. Hongjing Wu Prof. Guanglei Wu Yanyan Ren Prof. Xinghua Li Prof. Liuding Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(26):8864-8871
Uniform multishelled NiO, Co3O4, ZnO, and Au@NiO hollow spheres were synthesized (NiO and Co3O4 hollow spheres for the first time) by a simple shell‐by‐shell self‐assembly allowing for tuning of the the size, thickness and shell numbers by controlling the heat treatment, glucose/metal salt molar ratio, and hydrothermal reaction time. These findings further the development of synthetic methodologies for multishelled hollow structures and could open up new opportunities for deeper understanding of the mechanisms of shell‐by‐shell self‐assembly. Moreover, the double‐shelled NiO hollow sphere exhibits a higher photocatalytic activity for degradation of methyl orange than its morphological counterparts. 相似文献
7.
8.
Min Qiao Qiang Chen Shishan Wu Jian Shen 《Journal of Sol-Gel Science and Technology》2010,55(3):377-384
Novel ammonia and triethanolamine assisted sol–gel synthesis method was developed to fabricate the N-doped TiO2 hollow spheres. The prepared hollow spheres were in submicron size and had good morphology and high specific surface area.
Polystyrene (PS) latexes in size of 470 nm were used as the templates to fabricate PS/TiO2 core–shell spheres. Here ammonia and triethanolamine was first employed together to control the sol–gel process. The N-doped
TiO2 hollow spheres were got after calcinations of the core–shell spheres by using triethanolamine as N source, and the amount
of doped N could be easily adjusted by changing the amount of triethanolamine. The hollow spheres had distinct visible light
response, and the optical response shifted more to the visible region as the amount of doped N increases. The photodegradation
of methylene blue expressed the high photocatalytic activity of the N-doped TiO2 hollow spheres under visible light. 相似文献
9.
Formation of Triple‐Shelled Molybdenum–Polydopamine Hollow Spheres and Their Conversion into MoO2/Carbon Composite Hollow Spheres for Lithium‐Ion Batteries
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Dr. Yawen Wang Dr. Le Yu Prof. Xiong Wen Lou 《Angewandte Chemie (International ed. in English)》2016,55(47):14668-14672
Unique triple‐shelled Mo‐polydopamine (Mo‐PDA) hollow spheres are synthesized through a facile solvothermal process. A sequential self‐templating mechanism for the multi‐shell formation is proposed, and the number of shells can be adjusted by tuning the size of the Mo‐glycerate templates. These triple‐shelled Mo‐PDA hollow spheres can be converted to triple‐shelled MoO2/carbon composite hollow spheres by thermal treatment. Owing to the unique multi‐shells and hollow interior, the as‐prepared MoO2/carbon composite hollow spheres exhibit appealing performance as an anode material for lithium‐ion batteries, delivering a high capacity of ca. 580 mAh g?1 at 0.5 A g?1 with good rate capability and long cycle life. 相似文献
10.
Baodong Mao Enbo Wang Chungui Tian Chunlei Wang Meiye Li 《Journal of solid state chemistry》2007,180(2):489-495
Uniform hollow hematite (α-Fe2O3) spheres with diameter of about 600-700 nm and shell thickness lower than 100 nm are obtained by direct hydrothermal treatment of dilute FeCl3 and tungstophosphoric acid H3PW12O40 solution at 180 °C. The hollow spheres are composed of robust shells with small nanoparticles standing out of the surface and present a high-surface area and a weak ferromagnetic behavior at room temperature. The effect of concentration of H3PW12O40, reaction time and temperature for the formation of the hollow spheres are investigated in series of experiments. The formation of the hollow spheres may be ascribed to a polyoxometalte-assisted forced hydrolysis and dissolution process. 相似文献
11.
Guannan Sun Zhimin Chen Shanshan Wang Linmei Li Jianwei Fu Jiafu Chen Qun Xu 《Colloid and polymer science》2011,289(12):1397-1406
This article presents a novel route to prepare hollow silica microspheres with well-defined wall thickness by using cross-linked
polystyrene (PS) microspheres as templates with the assistance of supercritical carbon dioxide (SC-CO2). In this approach, the cross-linked PS templates can be firstly prepared via emulsifier-free polymerization method by using
ethylene glycol dimethacrylate or divinylbenzene as cross-linkers. Then, the silica shell from the sol–gel process of tetraethyl
orthosilicate (TEOS) which was penetrated into the PS template with the assistance of SC-CO2 was obtained. Finally, the hollow silica spheres were generated after calcinations at 600 °C for 4 h. The shell thickness
of the hollow silica spheres could be finely tuned not only by adjusting the TEOS/PS ratio, which is the most frequently used
method, but also by changing the pressure and aging time of the SC-CO2 treatment. Fourier transform infrared spectroscopy, transmission electron microscopy, and scanning electron microscope were
used to characterize these hollow silica spheres. 相似文献
12.
Wei Wei Chengliang Zhang Shujiang Ding Xiaozhong Qu Jiguang Liu Zhenzhong Yang 《Colloid and polymer science》2008,286(8-9):881-888
Hierarchically structured hydrogel hollow spheres with functional hydrogels located at desired sites are expected to have new properties. We have developed a facile swelling polymerization route using a polymer hollow sphere as template to synthesize hierarchically structured hydrogel hollow spheres. It is significant to pre-swell the template shell with good solvents, such as chloroform containing oil-soluble initiators to control interaction, thus, polymerization locus of different water-soluble functional monomers. Some representative hydrogel composite hollow spheres such as poly(N-isopropylarylamide) and poly(acrylic acid) with different morphologies have been synthesized. Hydrogels with functional groups can favorably complex with desired materials; hierarchically structured inorganic or polymer composite hollow spheres are synthesized by a sol–gel process of the inorganic precursor by using different hydrogel composite hollow spheres as templates. 相似文献
13.
Highly ordered three dimensional macroporous carbon spheres bearing sulfonic acid groups (MPCS-SO3H) were prepared by incomplete carbonization of glucose in silica crystal bead template, followed by sulfonation and removal of the template. The composition and porous structure of the obtained carbon spheres were investigated by physical adsorption of nitrogen, scanning electron microscopy, energy dispersive X-ray spectroscopy, and transmission electron microscopy techniques. While the Fourier-transform infrared spectroscopy was used to characterize the functional groups on the surface of carbon spheres. The catalytic properties of the MPCS-SO3H were evaluated by esterification of ethanol with acetic acid, indicating that MPCS-SO3H possess remarkable catalytic performance (high stability and acid catalytic ability) for the esterification. 相似文献
14.
模板法制备复合中空微球 总被引:3,自引:1,他引:2
本文报道以一种商品化的聚苯乙烯中空球为模板, 采用溶胀聚合技术合成了具有IPN(Inter-Penetrating Network)结构的复合中空球; 对其中的一种高分子网络进行化学改性引入所需官能团, 制得带有羧基的聚合物凝胶中空球; 利用凝胶诱导生长特性, 成功制得聚合物复合中空球. 此方法无需去除模板就可批量制备各种复合功能中空球. 相似文献
15.
Mukesh Agrawal Andrij Pich Nikolaos E. Zafeiropoulos Manfred Stamm 《Colloid and polymer science》2008,286(5):593-601
Submicron hollow spheres are an interesting class of materials that receive significant attention nowadays. Closed and mechanically
robust homogeneous hollow titania microspheres with as much shell thickness as 130 nm were fabricated by coating polystyrene
beads with titania nanoparticles using sol–gel chemistry and subsequently removing the core either via heating or a chemical
dissolution process. The thickness of the titania shell deposited on polystyrene core was finely tuned between 100 and 130 nm
by varying the concentration of titania precursor, i.e., Ti(OEt)4 salt from 0.5 to 2 mM during the coating process. The obtained hybrid core–shell particles and hollow microspheres were characterized
by scanning electron microscopy, transmission electron microscopy, infrared spectroscopy, X-ray diffraction, and thermo-gravimetric
analysis. The approach employed is well suited to the preparation of titania-coated polystyrene hybrid particles and hollow
titania spheres, which can find their applications as novel building blocks with unique optical properties for fabrication
of advanced materials, catalyst, and drug delivery system. 相似文献
16.
Xinyu Wang Hongqiang Wang Qifa Dai Qingyu Li Jianhong Yang Anna Zhang Zhixiong Yan 《Colloids and surfaces. A, Physicochemical and engineering aspects》2009,346(1-3):213-215
Irregular porous carbon spheres were successfully prepared from Na2SnO3 coated corn porous starch by carbonization. The product was characterized with X-ray diffraction and scanning electron microscope (SEM). It is verified that the irregular porous carbon spheres are composed of disordered carbon, and the skeleton and pores of the corn porous starch was well preserved after carbonization. The pore size of the irregular porous carbon spheres is almost the same, which is similar to that of the porous starch. And the pore size decreases from about 0.91 μm to 0.53 μm measured from the SEM pictures. The texture of the irregular porous carbon spheres is mainly determined by that of porous starch. 相似文献
17.
Shiquan Liu Meiying Wei Xueye Sui Xin Cheng Pegie Cool Gustaaf Van Tendeloo 《Journal of Sol-Gel Science and Technology》2009,49(3):373-379
Defects on hollow silica spheres synthesized in a tetraethylorthosilicate-octylamine-HCl-H2O system were recorded by scanning microscope. Based on the results, influences of synthesis composition on the formation
of these defects are discussed. It is evidenced that products prepared with different octylamine-to-tetraethylorthosilicate
ratios may have surface depressions, cracks and non-hollow microspheres. However, by changing water and acid additions, these
defects could be reduced or eliminated. Generally, samples synthesized with a large octylamine addition commonly exhibit surface
depressions. A small octylamine or a large water addition benefits the formation of solid silica microspheres among the product.
Acid, although is not indispensable for the formation of hollow spheres, helps to eliminate or reduce depressions on the hollow
shells. It is explained that the added acid gives rise to a relative localized fast hydrolysis versus condensation, facilitating
an easy mobility of hydrolyzed silica species, and consequently the shell surface is smoothened. 相似文献
18.
A novel method of fabricating composite particles with core–shell structures is demonstrated. The particles comprised monodisperse submicrometer-sized copolymer latex spheres as cores and Fe2O3 crystallites as shells. The shell was formed by controlled hydrolysis of aqueous iron solutions, and the growth of hematite on the surface of the copolymer spheres was controlled by slow injection. Hollow spheres were obtained by calcinations of the so-coated copolymer lattices at 500°C in air. The void size of these hollow spheres was determined by the diameter of the copolymer template, and the wall thickness could be easily controlled in the range of 20–60 nm by using this coating process. The structure and the composition of the spheres were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). It can be seen that a crystallite change and a crystal phase transformation occurred during coating and calcination of the composite spheres. The formation of the composite particles is simply explained by the nucleation of iron oxide on the surface of the latex followed by growth of the iron compound shell. 相似文献
19.
Y2O3:Eu3+ hollow spheres were successfully prepared with melamine formaldehyde(MF) spheres as template. The MF spheres played a significant role in directing the formation of the hollow shells which are composed of numerous primary nanoparticles. Furthermore, the shell thickness of these hollow spheres could be readily tailored by adjusting the dosage of MF template. Based on the photoluminescence(PL) investigation, the red emission intensities(613 nm) of these Y2O3:Eu3+ hollow spheres are greatly influenced by their shell thickness and it was found that hollow spheres with thin shell thickness and intact hollow structures permit a better PL performance. 相似文献
20.
Selective Functionalization of Hollow Nanospheres with Acid and Base Groups for Cascade Reactions
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Dr. Jinsuo Gao Xueying Zhang Yong Lu Prof. Shaomin Liu Dr. Jian Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(20):7403-7407
The inner‐surface functionalization of hollow silica spheres has rarely been reported and is still a challenging topic. Herein, we report a deacetalization–Henry cascade reaction catalyzed by dual‐functionalized mesoporous silica hollow nanospheres with basic amine groups (?NH2) on the internal shell and carboxylic acid groups (?COOH) on the external shell. The selective functionalization has been realized by a combination of “step‐by‐step post‐grafting” and “cationic surfactant‐assisted selective etching” strategy. Compared to unisolated catalyst, the selectively isolated acidic and basic dual catalyst provides excellent catalytic performance for the deacetalization–Henry cascade reaction in terms of both activity (>99 %) and selectivity (95 %). 相似文献