纳米TiO2复合分级球的制备及其形成机理研究

采用二甘醇为鳌合剂和反应液制备钛的醇酸盐前驱体球,然后180℃水热处理得到高度晶化的复合分级结构的TiO2球。用X射线衍射仪(XRD)、场发射扫描电子显微镜(FESEM)、傅里叶转换红外光谱仪(FT-IR)以及同步热分析仪(TGA-DSC)对样品进行表征,并探讨了TiO2复合分级球的形成机理。     

Synthesis of montmorillonite-chitosan hollow and hierarchical mesoporous spheres with single-template layer-by-layer assembly

In order to develop a facile and precisely controlled approach to synthesize hierarchical mesoporous materials with tailored property, in this work, a novel study was carried out to fabricate montmorillonite-chitosan hollow and hierarchical mesoporous spheres (MMTNS@CS-HMPHS) based on single-template layer-by-layer (LbL) assembly. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), specific surface area analysis and X-ray photoelectron spectroscopy (XPS) analyses were carried out to characterize the morphology and surface properties of MMTNS@CS-HMPHS. Benefitting from the unique lamellar structure of MMTNS, mesoporous channels are formed on the shell of MMTNS@CS hollow spheres, resulting in high surface area. Moreover, the surface functionalization and pore size of MMTNS@CS-HMPHS can be easily tuned, due to the tailored property through LbL assembly method. Besides the unique microstructure, MMTNS@CS-HMPHS also possesses the active sites generated from both MMT and chitosan, which greatly promotes its performance in fields of adsorption, drug delivery and catalyst supports, etc.     

Hydrothermal synthesis of PbS hollow spheres with single crystal-like electron diffraction patterns

PbS hollow spheres were successfully prepared by a sodium citrate-assisted hydrothermal process at 120 degrees C for 12 h, employing lead acetate trihydrate, thiourea and sodium citrate as precursors. The diameter of PbS hollow spheres is 200-400 nm, which is composed of about 50-80 nm nanoparticles. The synthesized product was characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), electron diffraction (ED), Fourier transform-infrared (FT-IR) spectroscopy, ultraviolet-visible spectrometer (UV-vis) and near-infrared absorption spectrometer (NIR). The effects of the reaction conditions on morphologies of PbS structures were investigated. Star-shaped and flat PbS crystals were obtained by changing some experiment conditions. The results show that temperature, sodium citrate concentration, sulfur sources and solvent play key roles on the final morphologies formation of PbS crystals. Especially, ED result indicates that PbS hollow spheres hold single crystal-like electron diffraction patterns. And the possible formation mechanism of hollow spheres was proposed.     

Bi_2MoO_6空心球的水热沉淀法制备及其光催化性能

以葡萄糖为前躯体,采用水热法制备胶体碳球,以其为模板通过水热沉淀法制备C/Bi2MoO6核壳结构,然后在350℃空气中煅烧,获得了具有良好光催化性能的Bi2MoO6空心球.通过SEM、XRD、FT-IR和BET等测试方法对该催化剂进行了表征;并对其形成机理及反应过程进行了初步探讨,以亚甲基蓝作为被降解物质,研究了其光催化活性。结果表明,Bi2MoO6空心球是由纳米晶粒组成的,壁厚约为30～50nm,平均直径约为0.6～0.8μm,采用胶体碳球作模板时制得的Bi2MoO6空心球比表面积为11.315m2/g,而直接合成的粉体比表面积为3.378m2/g。在黑管灯照射下,2.5h亚甲基蓝的降解率达到了91.95%。     

铁/镱掺杂二氧化钛空心球的制备及其光催化性能

用模板法制备铁/镱共掺杂二氧化钛空心球(Fe/Yb-TiO2HS),使用扫描电子显微镜(SEM)观察和X射线衍射(XRD)、X射线光电子能谱(XPS)、傅里叶红外光谱(FT-IR)、热失重(TG)等测试方法对对其进行了表征.使用浓度为20 mg/L的甲基橙溶液模拟废水,研究了铁/镱共掺杂二氧化钛空心球的催化性能.结果 ...     

水热法合成α-氧化铝空心微球

以葡萄糖和硝酸铝为原料,采用水热法合成大小及壁厚可控的α-氧化铝空心微球。通过扫描电子显微镜(SEM)、傅立叶红外光谱分析仪(FT-IR)、X射线衍射(XRD)、热分析(TG-DSC)等手段对合成产品进行表征。结果表明:得到的氧化铝空心微球分散性较好,可通过调节加入的葡萄糖浓度及硝酸铝量,得到大小及壁厚不同的氧化铝空心球,烧结温度对微球粒径大小影响不大,当烧结温度上升900℃时,壳层结构由不定形态变为γ-Al2O3,当烧结温度上升到1 100℃时,可得到α-Al2O3氧化铝空心微球。     

A novel route to synthesis Aluminum silicate hollow spheres having ZSM-5 structure in absence of template

A novel route to synthesize Aluminum silicate hollow spheres with thick walls having ZSM-5 structure without using any template at 150 °C was presented. X-ray diffraction (XRD), Scanning electron microscopy (SEM), TG/DTA, FT-IR and nitrogen adsorption were employed to characterize the morphology and microstructures of the as-prepared silica hollow spheres. Experimental results indicated that the hollow spheres had an average diameter of nearly 200 nm with a surface area of 342 m²/g.     

A facile approach to fabrication of PbS hollow spheres with improved polystyrene templates

This paper provides a simple route to produce monodisperse PbS hollow spheres by using cationic polystyrene (PS) micro-particles as templates. The templates used in our experiment, were prepared via emulsifier-free polymerization by using the cationic monomer 2-(methacryloyloxy) ethyltrimethylammonium chloride as co-monomer. X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTRI) were used to characterize the structure of the obtained PbS/PS composites and hollow PbS spheres. It was found that the as-produced samples are well-defined core-shell structures with an average diameter of about 0.98 μm. TEM showed that after the removal of the templates, the hollow structures were perfectly retained.     

Polydiphenylamine/carbon nanotube composites for applications in rechargeable lithium batteries

Polydiphenylamine/single walled carbon nanotube (PDPA/SWNT) composites were synthesized electrochemically aiming at their application as active electrode materials for rechargeable lithium batteries. The electrochemical polymerization of diphenylamine (DPA) on a SWNT film immersed in a 1 M HCl solution was studied by cyclic voltammetry. Comparing cyclic voltammograms recorded on a blank Pt electrode with those obtained for a SWNT film deposited on Pt electrode one observes in the latter case a decrease of the DPA reduction potential. To elucidate electrochemical polymerization mechanism, photoluminescence studies on DPA/SWNT and PDPA/SWNT systems were carried out. Additional information concerning the functionalization process of SWNT with PDPA was obtained by Raman and IR spectroscopy. Using the PDPA/SWNT composite as active material for the positive electrode of a rechargeable lithium cell (LiPF₆ electrolyte), the charge-discharge tests show a specific discharge capacity of ca. 245 mA h g⁻¹, much higher than the 35 mA h g⁻¹ for pure PDPA.     

Synthesis of Eu2O3 hollow submicrometer spheres through a sol–gel template approach

Submicrometer-sized hollow Eu₂O₃ spheres with a shell thickness of about 75 nm and inner diameter about 690 nm have been synthesized through a sol–gel method using PS/PE microspheres as templates. X-ray powder diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Field emission scanning electron microscopy (FESEM), and photoluminescence (PL) spectroscopy have been used for the characterization of the obtained hollow Eu₂O₃ spheres. The PL peak is obviously broadened compared with that of bulk Eu₂O₃. The mechanism of the formation of the hollow Eu₂O₃ spheres was discussed.     

Fabrication of hollow silver spheres by MPTMS-functionalized hollow silica spheres as templates

In this study, we provide a strategy to prepare the hollow silver spheres by accumulating the silver nanoparticles on the surface of 3-mercaptopropyltrimethoxysilane (MPTMS)-functionalized silica as templates, which was accomplished by the chemisorption between silver nanoparticles and thiol groups. Then, the resulting hollow silver spheres were obtained through the chemical wet etching process with 10 M HF solution. In conventional method, the fabrication of hollow silver spheres from core-shell spheres was not easy due to the difficulties in retaining the shell structures during core removal. The method in this paper could overcome this limitation. The major focus of study is on understanding the mechanism of formation of the hollow silver spheres through the self-assembly behavior by chemisorption between silver nanoparticles and thiol groups. The silver-coated silica and hollow silver spheres were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), high-resolution TEM (HR-TEM), and X-ray photoelectron spectroscopy (XPS).     

Template-free fabrication of TiO2 hollow spheres and their photocatalytic properties

Submicrometer-sized anatase TiO(2) hollow spheres were fabricated through a template-free solvothermal route using TiCl(4) as a raw material and a mixture of alcohols-acetone as solvent. Control of the hollow spheres' size was achieved by adjusting the ratio of alcohols to acetone. Products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution TEM, X-ray photoelectron spectra (XPS), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and thermogravimetric (TG) analysis. It was found that the formation process of the TiO(2) hollow spheres might include the hydrolysis of Ti(IV) with the water formed from the solvothermal etherification reaction, the aggregation of the anatase TiO(2) nanoparticles, and the Ostwald ripening. Furthermore, the as-prepared TiO(2) hollow nanostructures exhibited good photocatalytic activity for the degradation of phenol.     

One-pot template-free synthesis of mesoporous boehmite core-shell and hollow spheres by a simple solvothermal route

Uniform-sized and monodispersed boehmite core-shell and hollow spheres have been successfully synthesized using a template-free solvothermal route. The experimental parameters such as reaction duration, the trisodium citrate amounts and solvents are shown to play important roles in the formation of the AlOOH core-shell and hollow spheres. X-ray diffraction, Fourier transform IR, thermal gravimetric analysis, N₂ adsorption/desorption, scanning electron microscopy, transmission electron microscopy, and high-resolution TEM were used to characterize the products. The results show that the prepared polycrystalline hollow spheres are composed of well-aligned AlOOH nanowires and have an orthorhombic structure. Finally, a dissolution-renucleation mechanism was proposed for the formation of boehmite hollow structures.     

“蒸汽相转化”法制备球形多级Y沸石

本文采用“蒸汽相转化”法合成了球形多级Y沸石。采用X射线衍射(XRD), 扫描电镜(SEM), 透射电子显微镜(TEM), N₂吸附-脱附, 固态核磁共振(NMR)谱和傅里叶变换红外(IR)光谱等表征手段对制备材料的结构性能进行了表征。SEM观察结果表明合成的Y型沸石是由尺寸为50~300 nm的初级晶粒组成的球形多晶聚集体, 透射电镜观察结果表明多晶聚集体为空心Y型沸石。通过分析FT-IR, ²⁹Si NMR, SEM和TEM等表征结果, 提出了空心球形Y沸石的形成机理。     

Shape-controlled synthesis and properties of dandelion-like manganese sulfide hollow spheres

Dandelion-like gamma-manganese (II) sulfide (MnS) hollow spheres assembled with nanorods have been prepared via a hydrothermal process in the presence of l-cysteine and polyvinylpyrrolidone (PVP). l-cysteine was employed as not only sulfur source, but also coordinating reagent for the synthesis of dandelion-like MnS hollow spheres. The morphology, structure and properties of as-prepared products have been investigated in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), selected area electron diffraction (SAED), high-resolution transmission electron microscopy (HRTEM) and photoluminescence spectra (PL). The probable formation mechanism of as-prepared MnS hollow spheres was discussed on the basis of the experimental results. This strategy may provide an effective method for the fabrication of other metal sulfides hollow spheres.     

Preparation and photocatalytic activity of hollow ZnO and ZnO-CuO composite spheres

ZnO and ZnO-CuO composite hollow spheres were fabricated by using colloidal carbon spheres as templates. The morphology, structure and chemical composition of the as-prepared samples were investigated using field emission scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The photocatalytic activity of the hollow spherical products was evaluated by photocatalytic degradation of methylene blue (MB) aqueous solution at ambient temperature. The results indicated that the ZnO-CuO composite hollow spheres display higher photocatalytic efficiency than pure hollow ZnO products. The related photocatalytic mechanism was discussed based on the microstructure and properties of the ZnO and ZnO-CuO composite hollow spheres. The facile strategy for the preparation of ZnO-CuO hollow nanostructures can be applicable to the synthesis of other composite hollow spheres.     

Preparation of silica hollow fibers by surface-initiated atom transfer radical polymerization from electrospun fiber templates

Silica hollow fibers were produced by surface-initiated atom transfer radical polymerization (ATRP) from poly(methyl methacrylate-co-vinylbenzyl chloride) (P(MMA-co-VBC)) electrospun fibers combined with sol-gel process and subsequent calcination. Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) were used to characterize the intermediate products and the silica hollow fibers. The resulting silica hollow fibers are of high purity with amorphous morphology. The thickness of the hollow fibers is approximately 0.25 µm.     

Y2O3:Eu3+ core-in-multi-hollow microspheres: facile synthesis and luminescence properties

Y2O3:Eu3+ core-in-multi-hollow microspheres were synthesized via a facile hydrothermal method in the presence of glucose followed by a subsequent heat-treatment process. X-ray diffraction (XRD) pattern shows that the as-obtained hollow spheres are cubic phase of Y2O3. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) images indicate that the samples are three layer hollow spheres with a diameter of 2-4 microm and the outermost wall thickness of 100 nm, the size of the inner core is about 300-400 nm, and the sub-outer wall thickness is about 100 nm. X-ray energy dispersive spectrum (EDS) shows that the samples are composed of Y, Eu and O. Photoluminescence spectra show that the hollow spheres have a strong characteristic red emission corresponding to the 5D0 - 7F2 transition of Eu3+ ions under ultraviolet excitation. This method can be used to synthesize other rare earth oxide hollow luminescent materials.     

聚吡咯纳米粒子及聚吡咯-木质素磺酸空心球的制备

以三氯化铁为氧化剂,在静态聚合条件下,分别制备了聚.咯纳米粒子及聚吡咯-木质素磺酸空心球.采用扫描电子显微镜、透射电子显微镜、红外光谱、宽角X射线衍射对聚吡,及聚吡咯-木质素磺酸的形貌和结构进行了表征.研究结果表明,木质素磺酸钠用量对聚吡咯的形貌有重大影响.在元木质素磺酸盐存在,三氯化铁/吡咯物质的量比为1.0,25℃...     

From CdS aggregate spheres to PbS hollow spheres: a case study of the growth mechanism in chemical conversion

Monodisperse PbS hollow spheres were successfully prepared via using CdS aggregate spheres as template. The present strategy is based on the different solubilities of CdS and PbS. This process was intensively studied by time-dependent trails which were monitored by transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and photoluminescence spectroscopy (PL). Reaction temperature was found to play an important role in controlling the diffusion rate of Pb²⁺ ions and the quality of as-prepared PbS crystals, which finally leads to different shape evolution processes from the starting aggregate spheres to the final hollow spheres. Two growth mechanisms defined as kinetics-controlled process (KCP) and thermodynamics-controlled process (TDCP) were, respectively, proposed for the two conversion patterns observed at 30 and 90 °C. Moreover, specific structural evolution including primary crystal size, diameter growth, and shell thickness were also discussed in detail. This work is of great significance in elucidating the underlying mechanism of chemical conversion and could be potentially applied to synthesize other hollow architectures.