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无机空心微球含可容纳大量客体的中空部分,具有比表面积大、密度小、表面渗透能力强、稳定性好等特点,在化学、生物、材料科学和光电领域均有重要的应用,如控制释放胶囊(药物、颜料、化妆品、油墨)、催化剂及催化剂载体、分离材料、声学隔音材料以及电子学元件等。[1-3]空心球壳材料的制备方法通常有喷雾干燥法,乳液法[4],模板合成法[5]。近年来以胶体粒子为模板合成空心材料引起了人们的高度重视,其中聚苯乙烯微球(PSt)由于其形貌规整,粒径均一而被广泛用作形成空心结构的有机模板[6]。通过对锂离子电池正极材料的广泛研究,发现空心球壳型… 相似文献
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聚苯乙烯微球表面的链段堆积状态徐伟,陈殿勇,华中一,吕绪良,胡建华,府寿宽(复旦大学材料科学系,上海,200433)(复旦大学高分子科学系)关键词聚苯乙烯微球,聚合物链段,聚集态,扫描隧道显微镜用微乳液聚合法制备的聚苯乙烯微球与常规聚苯乙烯相比有许多... 相似文献
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以pH响应型微凝胶为模板制备出了二氧化锰空心球材料,并利用XRD、TGA、SEM、FT—IR和TEM等手段对其进行了表征.结果表明,通过调节KMn04的用量可以有效控制二氧化锰空心球的球壳厚度.对洗脱后上层清夜中的pH响应型微凝胶进一步研究发现,部分微凝胶呈现出非可逆的膨胀一收缩转变,这一现象主要是由于其内部的交联程度不高造成的.在对表征结果进行分析后提出了空心球结构的形成机理. 相似文献
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The effect of nonmetallic element P in electroless Ni‐P coating on the passivation process during chemical conversion treatment
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Pure Ni and electroless Ni‐P coating (ENPC) were passivated by a chemical conversion treatment. The passive films formed on pure Ni and ENPCs (with content of P 2.9, 7.2 and 11.7 at.% respectively) were analyzed by X‐ray photoelectron spectroscopy (XPS). High‐resolution XPS was also used to analyze the chemical states of the elements detected in the passive films. The results indicated that the detected Ni and P were in elemental states, and no compound with Ni and P element was detected in passive film, meaning that Ni and P did not participate in the formation of the passive film. The content of film‐forming reaction product in passive film increases with the content of element P in Ni‐P coating, suggesting that the nonmetallic P in Ni‐P coating played an important role in the formation of the passive film. The XPS results were used to analyze the formation mechanism of the passive film. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Chang‐Yuan Hu Xiao‐Ning Liao Feng‐Yi Li Rong‐Bin Zhang Rong‐Fa Zhang Ting‐Zhi Liu 《中国化学会会志》2007,54(6):1471-1476
Ni‐B and Ni‐B/CNTs amorphous alloy catalysts were prepared by chemical reduction and impregnation‐chemical reduction methods, respectively, and characterized by TEM, ICP, XPS, XRD, BET and CO chemisorption techniques. Their catalytic activities were evaluated in acetylene selective hydrogenation reaction. Based on characterizations, the effects of carbon nanotubes on Ni‐B amorphous alloy were attributed to both its structure effect, dispersing Ni‐B particles, leading to bigger surface area of active nickel and enhancing the thermal stability, and the electronic effect, resulting in electron‐rich nickel centers. Therefore, the superior thermal stability and acetylene selective hydrogenation activities of Ni‐B/CNTs to Ni‐B amorphous catalyst were obtained in the present study. 相似文献
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The Ni–P alloy coatings were obtained on alumina borate whisker‐reinforced pure aluminum composite by electro‐deposition. The initial electro‐deposition behavior of the Ni–P alloys on the composite and pure aluminum was studied, respectively. It was found that the composition and the morphology of materials had a distinct effect on the initial electro‐deposition behavior of the Ni–P alloys. The Ni–P alloy coatings preferred to nucleate at the composite as compared with the pure aluminum. Moreover, the Ni–P particles were prone to deposit at the whisker/Al interface in the composite. The Ni–P coatings were barely depositing upon the surface of whisker during the plating process. As the deposition time increased, the Ni–P particles that were deposited on the surface of the composite grew gradually. These Ni–P particles linked to each other and eventually covered the whisker surface. Moreover, it can be found that the surfaces of the composite were gradually covered by Ni–P coatings and the anticorrosion performance of the coated composite increased remarkably with the increase in the deposition time. When the deposition time is 60 min, only the Ni–P diffraction peak could be detected. In this case, the coated composite had significantly better corrosion resistant, which is attributed to the surface of composite was perfectly covered by the Ni–P coatings. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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The hollow composite spheres with a raspberry‐like structure were prepared by a self‐assemble heterocoagulation based on the inter‐particle hydrogen‐bonding interaction between the amide groups of hollow poly (N,N′‐methylenebisacrylamide‐co‐N‐isopropyl acrylamide) (P(MBA‐co‐NIPAAm)) microspheres and the carboxylic acid groups of poly(ethyleneglycol dimethacrylate‐co‐methacrylic acid) (P(EGDMA‐co‐MAA)) nanoparticles, in which P(EGDMA‐co‐MAA) nanoparticle acted as the corona and the hollow P(MBA‐co‐NIPAAm) microsphere behaved as the core. The control coverage of the corona particles on the surface of hollow core microspheres of P(MBA‐co‐NIPAAm)/P(EGDMA‐co‐MAA) hollow composite sphere was studied in detail through adjustment of the mass ratio between the core and corona particles. The effect of the pH on the stability of the raspberry‐like hollow spheres was investigated. The polymer particles and the resultant heterocoagulated raspberry‐like hollow spheres were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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Neodymium is used as a promoter of Ni‐B/CNTs amorphous alloy catalyst to modify its catalytic properties. Ni‐B/CNTs and Ni‐Nd(5wt%)‐B/CNTs catalysts were prepared by the impregnation chemical reduction method. Their catalytic performances were examined in acetylene selective hydrogenation, which is a crucial step in industrial polymerization processes, with the aim of the complete elimination of alkynes from alkene feedstocks. Experiments showed that the latter exhibited higher acetylene hydrogenation activity but lower ethylene selectivity. Catalysts were characterized by ICP, CO‐chemisorption, XPS, XRD and H2‐TPD techniques. On the basis of characterizations, the modification of Nd on Ni‐B/CNTs catalyst was related to its geometric and electronic effects. 相似文献
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Madiha A. Shoeib Medhat M. Kamel Salah M. Rashwan Omar M. Hafez 《Surface and interface analysis : SIA》2015,47(6):672-680
Composite Ni–P/nano‐TiO2 coatings were prepared by simultaneous electroless deposition of Ni–P and nano‐TiO2 on a low carbon steel substrate. The deposition was carried out from stirred solutions containing suspended nano‐TiO2 particles. The Ni–P and Ni–P/nano‐TiO2 coatings before and after heat treatment were characterized by X‐ray diffraction, scanning electron microscopy and energy dispersive X‐ray spectroscopy. The micro‐structural morphologies of the coatings significantly varied with the nano‐TiO2 content. The corrosion resistance of as‐plated and heat‐treated Ni–P and Ni–P/nano‐TiO2 coatings was investigated by anodic polarization, Tafel plots and electrochemical impedance spectroscopic (EIS) studies in 3.5% NaCl solution. Ni–P/nano‐TiO2 coating exhibited superior corrosion resistance over Ni–P coating. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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《Surface and interface analysis : SIA》2003,35(12):953-959
Direct adhesion between Ni–P‐plated iron and acrylonitrile–butadiene rubber, hydrogenated acrylonitrile–butadiene rubber and ethylene–propylene rubber was successful using 1,3,5‐triazine‐2,4,6‐trithiol monosodium salt (TTN) without any adhesive. Peel strength in the adherends was influenced by the amount of TTN employed. The interfacial structure between Ni–P‐plated iron and curing rubbers has been investigated with x‐ray microanalysis, x‐ray photoelectron spectroscopy and scanning electron microscopy. The TTN derivatives gathered locally at the interface between the Ni–P‐plated iron and curing rubber adherends. The TTN layer located near the interface is referred to as a reinforcement layer. This layer was in general ~70 nm thick and consisted of composites of the Ni salt of TTN. The TTN is thought to work as a binder that bonds between Ni–P‐plated iron and rubber chains. The single bonds between both Ni–P‐plated iron and rubber TTN was confirmed from Kraus plots and model experiments using TTN. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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The multi‐shaped amorphous alloy (Ni‐B) powders were prepared by complexing reduction route using sodium borohydride (NaBH4) as reductant with assistance of ultrasonic wave. The selected complexants, i.e. water, ammonia, salicylic acid, and ethylene diamine tetraacetic acid (EDTA) possess sequentially escalating complexation ability. The chemical composition and shapes of the product samples obtained under different conditions were characterized by X‐ray powder differaction, selected area electron diffraction, and transmission electron microscope. The influence of reaction conditions such as the types of Ni‐B, temperatures, NaBH4 concentrations, and sodium hydroxide (NaOH) content on the hydrogen generation rate of hydrolysis of NaBH4 solution were investigated in detail. The results show that the as‐prepared Ni‐B powders all belong to amorphous alloy with variable element contents, and the Ni‐B sample prepared from EDTA complexation, possessing the best fineness and dispersity, has the strongest catalytic activity. The mean apparent activation energy of the hydrolysis reaction is 64.90 kJ · mol–1. The NaBH4 concentration has little impact on hydrogen generation rate, implying that the catalytic hydrolysis of NaBH4 solution should be the pseudo zero‐order reaction. Keeping the NaOH content at below 5 % could inhibit the hydrolysis of NaBH4 solution, but the NaOH contents from 10 % to 15 % will significantly promote the hydrolysis rate of NaBH4. The hydrolysis reaction mechanisms, especially the effect of NaOH content on the hydrolysis reaction were also analyzed. 相似文献
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Nitrogen‐containing organic compounds are valuable in many fields of science and industry. The most reliable method for the construction of C(sp2)–N bonds is undoubtedly palladium‐catalyzed amination. In spite of the great achievements made in this area, the use of expensive Pd‐based catalysts constitutes an important limitation for large‐scale applications. Since nickel is the least expensive and most abundant among the group 10 metals, the interest in Ni‐based catalysts for processes typically catalyzed by palladium has grown considerably over the last few years. Herein, we revise the development of Ni‐catalyzed amination reactions, emphasizing the most relevant and recent advances in the field. 相似文献
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Hierarchical Hollow Nanoprisms Based on Ultrathin Ni‐Fe Layered Double Hydroxide Nanosheets with Enhanced Electrocatalytic Activity towards Oxygen Evolution
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Dr. Le Yu Jing Fan Yang Dr. Bu Yuan Guan Dr. Yan Lu Prof. Xiong Wen Lou 《Angewandte Chemie (International ed. in English)》2018,57(1):172-176
The oxygen evolution reaction (OER) is involved in various renewable energy systems, such as water‐splitting cells and metal–air batteries. Ni‐Fe layered double hydroxides (LDHs) have been reported as promising OER electrocatalysts in alkaline electrolytes. The rational design of advanced nanostructures for Ni‐Fe LDHs is highly desirable to optimize their electrocatalytic performance. Herein, we report a facile self‐templated strategy for the synthesis of novel hierarchical hollow nanoprisms composed of ultrathin Ni‐Fe LDH nanosheets. Tetragonal nanoprisms of nickel precursors were first synthesized as the self‐sacrificing template. Afterwards, these Ni precursors were consumed during the hydrolysis of iron(II) sulfate for the simultaneous growth of a layer of Ni‐Fe LDH nanosheets on the surface. The resultant Ni‐Fe LDH hollow prisms with large surface areas manifest high electrocatalytic activity towards the OER with low overpotential, small Tafel slope, and remarkable stability. 相似文献