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Ag/SBA-15纳米复合材料的超临界流体沉积法制备、性能表征和催化特征 总被引:4,自引:0,他引:4
用超临界流体沉积法以无机盐为前驱物制备纳米复合材料.超临界二氧化碳为溶剂,乙醇或乙二醇为共溶剂,AgNO3为前驱物,SBA-15为载体,在50℃、23~25MPa、3~24h条件下制备担载型纳米复合材料.反应结束后,经焙烧、还原处理,可得到Ag/SBA-15纳米复合材料.经XRD、TEM表征发现,担载的Ag纳米粒子分散均匀,粒径范围3~7nm;纳米线宽度5~9nm,长度由十几纳米到几微米,分散性较好.实验研究表明,超临界流体沉积法是制备纳米复合材料的有效方法,选择合适的共溶剂可以用超临界二氧化碳溶解无机盐.选择合适的沉积条件可以控制复合材料中金属相的形态. 对制备的复合材料进行催化活性评价表明,300℃下CO选择氧化反应可以完全转化. 相似文献
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SiO2-TiO2两元气凝胶的制备及其结构表征 总被引:5,自引:0,他引:5
SiO2-TiO2两元气凝胶是一种新型纳米光催化氧化剂。本文以正硅酸乙酯(TEOS)、钛酸丁酯为原料,以乙醇为溶剂,分别以HNO3、醋酸为催化剂用溶胶-凝胶法经超临界干燥制备出了SiO2-TiO2两元气凝胶。研究了不同催化剂以及SiO2:TiO2不同配比等制备因素对溶胶-凝胶过程的影响。用BET、XRD、SEM等测试方法对其结构进行了研究,结果表明:所制备的SiO2-TiO2两元气凝胶具有大比表面积(600m^2g^-1),纳米多孔结构(骨架颗料约为30-50nm, 孔洞尺寸为几十nm);经乙醇超临界干燥所得的TiO2为锐钛矿型;所制备的SiO2-TiO2两元气凝胶比纯TiO2气凝胶骨架结构强度得到明显增强。 相似文献
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通过旋涂成膜方法制备了聚芴(PF)/乙基氰乙基纤维素[(E-CE)C]共混物超薄膜(厚度约为50nm),用原子力显微镜(AFM)、透射电子显微镜(TEM)研究了共混物超薄膜形态结构,并用荧光光谱仪研究了共混物超薄膜中聚芴的光致发光性能.实验发现,超薄膜表面形态结构分布均一,相结构随着(E-CE)C含量增加有规律的变化,表现为PF逐渐被(E-CE)C均匀"分隔"开来.还发现该超薄膜在纳米尺度范围内发生垂面微相分离.同时,超薄膜中聚芴发射光谱随(E-CE)C含量增加发生蓝移,发射峰半高宽变窄.实验结果表明高速旋涂制得的超薄膜形态结构表现出显著的浓度依赖性,明显地影响PF发射光谱性质. 相似文献
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从硅太阳能电池正银浆料用有机载体的挥发性出发,研究了5种常用有机溶剂的挥发性,选取松油醇、丁基卡必醇以及丁基卡必醇醋酸酯3种溶剂作为混合溶剂。以乙基纤维素为增稠剂制备有机载体,研究了其含量对正银浆料丝网印刷性能及光电转换性能的影响。以蓖麻油为触变剂,研究了其含量对丝网印刷烧结后细栅线电极高宽比以及光电转换效率的影响。结果表明:当乙基纤维素的含量为6%时,正银浆料的印刷性能最好,光电转换效率可达17.707%;当蓖麻油的含量为3%时,所得细栅线的高宽比较高,光电转换效率为17.775%。 相似文献
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Shiping Zhan Liyun Cui Qicheng Zhao Jingchang Wang Shuhua Chen Shiqiang Ding 《Particulate Science and Technology》2014,32(1):61-69
A biodegradable triblock copolymer of poly(L-lactide)–poly(ethylene glycol)–poly(L-lactide) (PLLA-b-PEG-b-PLLA) was synthesized via a new process by the ring-opening polymerization of L-lactide with PEG as macroinitiator and Sn(Oct)2 as catalyst. The structure and molecular weight of the polymer were characterized by 1H NMR spectra, Fourier transform infrared spectroscopy (FTIR), and gel permeation chromatography (GPC). Then the microparticles were prepared with the synthesized copolymer by supercritical antisolvent (SAS) process. The optimal operating conditions were explored using an orthogonal array design. The effects of the mixed organic solvent, the concentration of polymer solution and the flow rate of polymer solution on the morphology and thermal properties of the microparticles were investigated experimentally. The morphology, size and thermal properties of microparticles were characterized by scanning electron microscopy (SEM), laser particle size analyzer, x-ray diffractometer (XRD) and differential scanning calorimeter (DSC) respectively. The results indicated that the use of mixed solvent (dichloromethane/acetone) and the polymer concentration played important roles on particle morphology, size and size distribution. In addition the PLLA-PEG-PLLA particles prepared by supercritical antisolvent process have less crystalline. 相似文献
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《Advanced Powder Technology》2014,25(2):787-794
In this study, Licorice extract (LE) microparticles were successfully prepared using antisolvent precipitation process. Ethyl acetate and dimethyl sulfoxide, were used as the antisolvent and solvent, respectively. By means of orthogonal experimental design, the influences of several process parameters on the mean particle size (MPS) were investigated. The concentration range of the LE solution, the volume ratio of solvent to antisolvent, dripping speed, and temperature were 4.3–34.5 mg/mL, 1:1–1:12, 1–10 mL/min, and 20–35 °C, respectively. Based on the above orthogonal experiments, the optimum antisolvent precipitation process conditions were found to be: temperature 20 °C, concentration of the LE solution 17.2 mg/mL, volume ratio of solvent to antisolvent 1:4, dripping speed 10 mL/min. The LE microparticles were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform-infrared (FT-IR) spectroscopy, thermal gravimetric analysis (TG), differential scanning calorimetry (DSC), HPLC analysis and dissolution test. And the morphology, crystalline state and chemical structure, drug purity, dissolution rate and bioavailability of LE microparticles were investigated. Under optimum antisolvent precipitation process conditions, the MPS of LE microparticles reached to 85.3 nm, and with uniform distribution. And the LE microparticles had the same chemical structure as the unprocessed drug, but the crystallinity was reduced, purity was increased. Furthermore, the water solubility increased from 4.82 mg/mL to 16.10 mg/mL, and bioavailability is increased by 64.36%. 相似文献
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超临界抗溶剂法制备聚乳酸微球 总被引:2,自引:0,他引:2
采用超临界抗溶剂技术,对影响聚乳酸(PLA)微球粒径的溶液浓度和溶剂配比进行了初步研究。在温度38℃、压力10 MPa、溶液流速1.0mL/min、喷嘴直径300μm条件下,研究不同溶液浓度和溶剂配比对聚乳酸微粒粒径和粒径分布的影响。结果表明:当聚乳酸质量浓度为10 mg/mL、混合溶剂二氯甲烷和丙酮的体积比为V(CH_2:Cl_2):V(CH_3COCH_3)=1:2时效果最好,得到的粒堆松软,粒径集中在530~950 nm,粒径分布窄,吹干只需12 min。 相似文献
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A. Montes M. D. Gordillo S. Schindhelm C. Pereyra E. J. Martinez De La Ossa 《Particulate Science and Technology》2013,31(5):424-430
Supercritical antisolvent (SAS) technique is an appropriate process to obtain micro- and nanoparticles. The application of this process has, until now, been explored in a variety of different fields including: explosives, polymers, pharmaceutical compounds, colouring matter, superconductors, catalysts, and inorganic compounds. Biocompatible and biodegradable polymers are playing more and more important roles in pharmaceutical areas such as tissue engineering and drug delivery. Formulation of these polymers into suitable solid-state forms plays an important role in safety, stability, and efficiency of the products. Ethyl cellulose is commonly used as drug carrier in controlled delivery systems. In this work, particles of ethyl cellulose have been precipitated by SAS using CO2 as antisolvent and dichloromethane (DCM) as solvent. We studied the effects of concentration on the particle size distribution (PSD) of the precipitates. Ethyl cellulose size-controlled particles have been produced in the micrometer range 3.8–5.0 μm, and an increase of the mean particle diameter (MPD) was observed with the increase of the concentration of the solution. 相似文献
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Dual‐Source Precursor Approach for Highly Efficient Inverted Planar Heterojunction Perovskite Solar Cells 下载免费PDF全文
Deying Luo Lichen Zhao Jiang Wu Qin Hu Yifei Zhang Zhaojian Xu Yi Liu Tanghao Liu Ke Chen Wenqiang Yang Wei Zhang Rui Zhu Qihuang Gong 《Advanced materials (Deerfield Beach, Fla.)》2017,29(19)
The highest efficiencies reported for perovskite solar cells so far have been obtained mainly with methylammonium and formamidinium mixed cations. Currently, high‐quality mixed‐cation perovskite thin films are normally made by use of antisolvent protocols. However, the widely used “antisolvent”‐assisted fabrication route suffers from challenges such as poor device reproducibility, toxic and hazardous organic solvent, and incompatibility with scalable fabrication process. Here, a simple dual‐source precursor approach is developed to fabricate high‐quality and mirror‐like mixed‐cation perovskite thin films without involving additional antisolvent process. By integrating the perovskite films into the planar heterojunction solar cells, a power conversion efficiency of 20.15% is achieved with negligible current density–voltage hysteresis. A stabilized power output approaching 20% is obtained at the maximum power point. These results shed light on fabricating highly efficient perovskite solar cells via a simple process, and pave the way for solar cell fabrication via scalable methods in the near future. 相似文献
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Well dispersed nickel nanoparticles with uniform size were synthesized via a modified hydrazine reduction route without any surfactant introduced. Ethanol was used as solvent and played the complementary reducing role. The as-prepared samples were characterized by XRD, FESEM, TEM and TG. Pure metallic Ni could be easily obtained when ethanol instead of water was used as solvent. The particle surface was much improved when ethanol was involved in the reduction process at high temperature. The resultant particles have smooth surface and uniform size of about 50 nm. The nickel powders have an oxidization temperature of about 200 °C. The formation process was discussed based on the experimental results. 相似文献
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《Advanced Powder Technology》2019,30(8):1522-1530
Soy isoflavone (SIF) nanoparticles were prepared using dimethyl sulfoxide as a solvent and water as an antisolvent. Response surface methodology was used to analyse the influences of several process parameters on the mass median diameter (D50). The SIF concentration (20–40 mg/mL), volume ratio of antisolvent to solvent (5–7 mL/mL), stirring speed (800–1600 r/min), and reaction time (2–4 min) were optimized. The optimal conditions were determined to be a SIF concentration, volume ratio of antisolvent to solvent, stirring speed and reaction time of 29 mg/mL, 7 mL/mL, 1533 r/min and 3 min, respectively. Satisfactory D50 of SIF (101.24 ± 12.21 nm) were achieved. The processed and unprocessed SIFs were tested and characterized. By comparing the parameters, the chemical properties of the processed and unprocessed SIFs did not change, but the water dissolution rate of the prepared SIF nanoparticles was greatly enhanced. 相似文献
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Yousef Bakhbakhi Mohammad Asif Achmad chafidz AbdelHamid Ajbar 《Advanced Powder Technology》2013,24(6):1006-1012
Supercritical carbon dioxide (scCO2) was used as antisolvent to precipitate griseofulvin (GF), an orally administered antifungal drug, from methylene chloride (DCM) using the supercritical antisolvent (SAS) process. The influence of different operating parameters such as antisolvent addition rate, temperature, concentration, and solution addition rate on product characteristics (particle size and size distribution, and morphology) has been analyzed. This investigation shows that with an adequate selection of process conditions it is possible to selectively produce crystalline needle-shaped particles with narrow size distribution. 相似文献
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To investigate the effects of solvents on the microstructure, porous TiO2 films have been prepared by sol-gel method using hydroxypropyl cellulose as the additive. Ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethanol, and the mixed solution of half ethylene glycol monomethyl ether and half ethanol were chosen as the solvents. Infrared spectra, scanning electron microscope micrographs, and X-ray diffraction patterns have been studied to characterize the microstructure of the sol and film samples. The results showed that mesoporous TiO2 films with the pore size around 20 nm, 10 nm and 6 nm were obtained when propylene glycol monomethyl ether, the mixed solution of half ethylene glycol monomethyl ether and half ethanol, and ethanol were used as solvent, respectively. It was found that COC group in the solvent was beneficial to enlarge the pore size, because the oxygen bridge in the COC groups could be pulled out and act with titanoxane polymers. When ethylene glycol monomethyl ether was used as the solvent, macroporous TiO2 film with pore size around 200 nm was obtained. This can be ascribed to the high enough concentration of effective COC groups of the solvent. 相似文献