共查询到20条相似文献,搜索用时 93 毫秒
1.
2.
3.
首先采用溶剂热法制备粒径均匀分散性良好的Fe3O4亚微米粒子,在对其包覆上一层碳膜进行表面修饰后,采用共沉淀法将硝酸根插层LDHs包覆到磁性粒子的表面,然后500℃焙烧2 h得到磁性镁铝复合氧化物亚微米粒子。这种磁性镁铝复合氧化物亚微米粒子具有以镁铝复合氧化物为壳层,Fe3O4为核的核壳结构,其中壳层厚度为20 nm左右,对其进行二次包覆后壳层厚度可达到50 nm左右,并可以方便的通过重复包覆焙烧过程进行调节,从而实现磁性镁铝复合氧化物亚微米粒子的控制制备。同时,磁性镁铝复合氧化物亚微米粒子具有较强的磁性,其比饱和磁化强度为23.3 emu·g-1,对其进行二次包覆并焙烧后为20.1 emu·g-1。 相似文献
4.
5.
二氧化硅/聚苯乙烯单分散性核/壳复合球的制备 总被引:9,自引:0,他引:9
采用无皂乳液聚合包覆 ,制备了二氧化硅 聚苯乙烯单分散核 壳 (SiO2 PS)复合颗粒 ,包覆层厚度达到 10 0nm .选择 80~ 2 5 0nm二氧化硅粒径作为核颗粒 .为提高包覆效率 ,二氧化硅颗粒先用偶联剂甲基丙烯酰 (3 三甲氧基硅烷 )丙酯 (MPS)进行不同程度的表面改性 .控制MPS的结合率和单体的初始浓度可提高包覆效率 ,同时得到了单分散性复合颗粒 ,用透射电镜 (TEM)观察复合粒子的核 壳形态 .用动态光散射法 (DLS)测量表明所得复合颗粒具有单分散性 . 相似文献
6.
通过光阳极协同包覆的策略抑制Zn?Cu?In?Se(ZCISe)量子点敏化太阳能电池(QDSC)中光阳极/电解液界面上的电荷复合过程,提高电荷收集效率和电池光伏性能。采用溶液法在ZCISe量子点敏化的光阳极表面依次沉积包覆ZnS和SiO2双钝化层,实现较单一ZnS包覆层更有效的界面电荷复合抑制作用,从而提高QDSC的性能。在包覆ZnS/SiO2双钝化层后,所组装的ZCISe QDSC光电转换效率由传统单一ZnS包覆的12.17%提高到13.23%,这归因于双钝化层对光阳极/电解液界面电荷复合过程的有效抑制,电荷收集效率得到相应提升。 相似文献
7.
纳米级包覆层厚度对染料敏化太阳电池中电子注入效率和电子寿命的影响 总被引:1,自引:0,他引:1
选取氧化钐作为包覆材料, 采用浸渍法对已烧结好的纳米TiO2多孔薄膜电极进行修饰, 并将其应用于染料敏化太阳电池中, 研究了纳米级氧化钐包覆层厚度及均匀性对染料敏化太阳电池中电子注入效率和电子复合过程的影响和作用机制. 结果表明, 包覆层厚度对电子注入效率和电子复合具有明显影响, 且电子注入效率和电子寿命随包覆层厚度的增加而呈现相反的变化趋势, 包覆层厚度在0.4 nm以内, 电池性能最好. 相似文献
8.
9.
采用聚苯乙烯磺酸钠(PSS)和聚二烯丙基二甲基氯化铵(PDDA)两种聚电解质, 通过静电层层自组装成功地将MCM-41介孔二氧化硅纳米粒子包覆到聚苯乙烯(PS)微球表面. 实验结果表明, 当以尺寸为1.4 μm的PS微球为核时, 包覆了两个聚电解质双层(PDDA/PSS)2的PS(PDDA/PSS)2(PDDA/MCM-41)复合结构微粒与包覆了一个聚电解质双层(PDDA/PSS)的PS(PDDA/PSS)(PDDA/MCM-41)复合结构微粒相比, 复合结构微粒之间的交联程度降低, 但是MCM-41纳米粒子在聚苯乙烯微球表面的包覆都比较松散, 且产物中存在大量杂质. 而当以尺寸为5 μm的聚苯乙烯微球为核时, MCM-41纳米粒子紧密地包覆在聚苯乙烯微球表面, 复合结构微粒之间只有少量桥连物, 且产物中杂质很少. 相似文献
10.
采用喷雾干燥与高温煅烧相结合的方法制备了球形LiTi2(PO4)3/C复合水系负极材料, 探讨了基于不同包覆机制的有机碳源和碳包覆量对LiTi2(PO4)3/C复合负极电化学性能的影响. 结果表明, 碳包覆量过低时不足以阻止水的侵蚀, 而碳含量过高时锂离子扩散的阻力过大, 磷酸钛锂电极最优碳包覆质量分数为13%. 碳包覆的均匀性和包覆层厚度是影响电极性能的两个重要因素. 基于原位聚合包覆机制的聚多巴胺包覆磷酸钛锂颗粒最均匀, 碳化后微晶结构较好, 具有良好的电子导电性, 以聚多巴胺为碳源制备的LiTi2(PO4)3/C复合负极性能最优. 相似文献
11.
W. Ortega-Lara D. A. Cortés-Hernández S. Best R. Brooks L. Bretado-Aragón D. Rentería-Zamarrón 《Journal of Sol-Gel Science and Technology》2008,48(3):362-368
In order to obtain materials for bone tissue replacement and regeneration that show an appropriate bioactivity, antibacterial
behavior and higher mechanical properties than those of the existing bioactive systems, titania–wollastonite materials were
obtained by both solid state reaction and sol–gel methods. In the solid state reaction process, titania and wollastonite powders
were mixed and sintered. Two different types of materials were obtained by sol–gel: (i) using titanium butoxide, calcium nitrate
tetrahydrate and tetraethyl orthosilicate as precursors or (ii) mixing titanium butoxide with wollastonite powder. The in
vitro bioactivity was assessed by immersing samples in simulated body fluids for different periods of time. Alamar blue assays
and osteoblast-like cells were used for testing citotoxicity. A higher bioactivity was observed on the samples synthesized
by sol–gel. However, a higher cell proliferation was observed on the samples obtained by solid state reaction. 相似文献
12.
Metallic Ag nanoparticles-incorporating titania films were prepared using the sol-gel method. X-ray diffraction (XRD) patterns,
UV/Vis optical spectra and transmission electron microscopy (TEM) images were recorded to characterize the Ag/titania composite
films. Electrometer was used to estimate the resistance of Ag/titania composite film to understand the effect of the incorporation
of metallic Ag nanoparticles on the electrical properties of titania film. The results showed that metallic Ag nanoparticles
distributed randomly in titania film and most metallic Ag particles size was in the range of 5–15 nm. The agglomeration of
a small quantity of metallic Ag particles occurred and when the amount of Ag species was increased the agglomeration was enhanced.
The resistance of Ag/titania composite films decreased greatly compared with pure titania film. 相似文献
13.
Hierarchical‐Structured Anatase‐Titania/Cellulose Composite Sheet with High Photocatalytic Performance and Antibacterial Activity 下载免费PDF全文
Dr. Yan Luo Prof. Dr. Jianguo Huang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(6):2568-2575
Bulk hierarchical anatase‐titania/cellulose composite sheets were fabricated by subjecting an ultrathin titania gel film pre‐deposited filter paper to a solvo‐co‐hydrothermal treatment by using titanium butoxide as the precursor to grow anatase‐titania nanocrystallites on the cellulose nanofiber surfaces. The titanium butoxide specie is firstly absorbed onto the nanofibers of the cellulose substance through a solvothermal process, which was thereafter hydrolyzed and crystallized upon the subsequent hydrothermal treatment, leading to the formation of fine anatase‐titania nanoparticles with sizes of 2–5 nm uniformly anchored on the cellulose nanofibers. The resulting anatase‐titania/cellulose composite sheet shows a significant photocatalytic performance towards degradation of a methylene blue dye, and introduction of silver nanoparticles into the composite sheet yields an Ag‐NP/anatase‐titania/cellulose composite material possessing excellent antibacterial activity against both Gram‐positive and Gram‐negative bacteria. 相似文献
14.
Jiang Y Yang D Zhang L Li L Sun Q Zhang Y Li J Jiang Z 《Dalton transactions (Cambridge, England : 2003)》2008,(31):4165-4171
Protamine, a kind of cationic protein extracted from sperm nuclei, was employed for the first time in vitro to induce the formation of a titania/protamine nanoparticle composite from a water-stable titanium precursor, titanium(iv) bis(ammonium lactato) dihydroxide (Ti-BALDH). The resulting titania/protamine nanoparticle composite was extensively characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The titania/protamine nanoparticle composite was of amorphous structure, and exhibited a different morphology from those prepared by an alkali-catalyzed approach. The catalyzing and templating function of protamine involved in the synthesis of the nanoparticle composite is discussed, and a mechanism tentatively proposed. In addition, the effects of pH and temperature on the amount and size of as-prepared titania/protamine nanoparticle composite were systematically investigated. 相似文献
15.
《中国化学会会志》2017,64(8):978-985
Alumina/titania composite aerogels with different titania contents were synthesized by the sol–gel process and supercritical ethanol drying. The structures and morphologies of synthesized aerogels were analyzed by X‐ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetry, and N2 adsorption–desorption tests. Supercritical ethanol drying induced the crystallization of titania, which prompted the transformation of the structure from pseudoboehmite to γ‐Al2O3 . Reversely, alumina retarded the anatase‐to‐rutile transformation of titania. The content of titania significantly affected the structure and morphology of alumina/titania composite aerogels. A high content of titania (≥40%) resulted in the phase separation of titania particles, which grew to form the anatase phase octahedral particles with well‐developed facets. When the titania content was low, titania particles could be homogeneously dispersed in alumina particles to form spherical clusters with the poor crystallinity. Titania particles were in the anatase phase, and no rutile phase was formed until the temperature rose to 1000°C. In addition, titania addition resulted in a decrease in the specific surface area (SSA) of alumina aerogels because the SSA of titania was lower than that of alumina aerogels. 相似文献
16.
17.
Song C Wang D Gu G Lin Y Yang J Chen L Fu X Hu Z 《Journal of colloid and interface science》2004,272(2):340-344
Silver-coated poly(methyl acrylic acid) (PSA) core-shell colloid particles were prepared by an in situ chemical reduction method. Crystalline silver/titania composite hollow spheres were obtained by coating the as-prepared PSA/silver particles with an amorphous titania layer and subsequently calcining in Ar atmosphere. SEM and TEM investigation indicated that the size of the as-prepared PSA/silver and PSA/silver/TiO(2) core-shell particles and silver/titania composite hollow particles was fairly uniform and the wall thickness of the hollow spheres was in the range of 40-80 nm. UV-vis absorption spectra were recorded to investigate their optical properties. 相似文献
18.
Thorough infiltration of CdS nanoparticles into spaces of titania nanorod and nanotube arrays was achieved by an ac electrodeposition technique to construct composite films of CdS over titania. The substrate affected not only the electrodeposition rate but also the oriented growth of CdS. A photocurrent much larger than the simple summation of those arising from the two component layers of CdS and titania was detected for both composite films under visible-light illumination. Such an enhancement in the photocurrent was even more prominent for the composite film based on the titania nanorod arrays, which was contributed to the higher charge separation rate arising from the nearly single-crystalline nanorods when compared with the polycrystalline nanotubes. 相似文献
19.
《Electrochemistry communications》2002,4(11):871-876
An occlusion electrosynthesis method for preparing semiconductor-based composite films, is illustrated by dispersing Degussa P-25 titania particles in a titania film matrix supported on a transparent conducting oxide (TCO) electrode. The titania film matrix was cathodically deposited on the TCO surface. The resultant composite film has superior photocatalytic and photoelectrochemical properties relative to an electrosynthesized titania film containing no occluded particles. An important feature of the methodology described here is that the semiconductor particles can be separately prepared, optimized or otherwise tailored for a specific application, prior to their occlusion within the continuous phase matrix. 相似文献
20.
《Solid State Sciences》2012,14(10):1467-1470
Wollastonite ceramic matrix composites are multi-materials including the crystalline wollastonite and the residual glass phases. The relative permittivity (simplified as permittivity) of the crystalline wollastonite is used to evaluate the dielectric properties of the wollastonite ceramic matrix. Usually, the permittivity of the crystalline wollastonite is estimated to be 8.6, however, the residual glasses in wollastonite ceramic matrix are often unknown. In this study, the Clausius–Mosotti model is utilized to calculate the permittivity of the crystalline wollastonite from molecular polarizability. Molecular polarizabilities as the crystalline wollastonite polarizability are calculated by the ionic and oxide additivity rules. The permittivity of prepared glasses is used instead of that of the remaining glasses and estimated to 4.65. The composite permittivity of the wollastonite ceramic matrix is calculated by Lichnetecker logarithm rules. Compared with measurements, the calculated permittivity of wollastonite ceramic matrix corresponds well with measurements. The application of this simple calculation technique allows the assessment of the relative permittivity for ceramic matrix. 相似文献