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1.
由于电子和信息行业的需要, 过去十年锂离子电池得以快速发展. 目前, 锂离子电池仍呈现需求量增长的趋势, 对锂离子电池的安全性要求也越来越高. 因此促使寻找一种比碳/石墨材料更安全, 循环性能更理想的锂离子电池负极材料以满足电动汽车等新兴行业的需求. 尖晶石型Li 4Ti 5O 12作为“零应变材料”具有优异的循环稳定性、价格便宜、容易制备、较高的平台电压和良好的安全性, 已成为锂离子动力电池负极材料的研究热点, 被认为是目前最具应用前景的锂离子电池负极材料. 由于形貌选择对于Li 4Ti 5O 12材料的电化学性能有着至关重要的影响, 本文综述了球形、多孔(中空)结构、纳微结构、核壳结构等不同形貌Li 4Ti 5O 12的合成及其性能研究的最新进展; 总结了各种形貌的优点, 已解决和待解决的问题, 常用合成方法以及各自的适应领域; 并对Li 4Ti 5O 12材料的发展趋势进行了展望. 相似文献
2.
本文综述了各种形貌的纳米Co 3O 4的制备及其应用。制备纳米Co 3O 4的方法有很多,包括热分解、水热法、溶剂热法、化学喷雾热分解、化学气相沉积和溶胶-凝胶法。各种形貌的Co 3O 4被制备,如纳米球、纳米立方体、纳米管、纳米棒、纳米片、纳米纤维和介孔结构。Co 3O 4是一种重要的磁性P-型半导体,在锂离子电池、超级电容器、电致变色、磁性材料、气体传感器和催化剂等诸多领域有比较广泛的应用。 相似文献
3.
采用两步水热法在泡沫镍基底上合成了具有纳米棒形貌的Co 3O 4@MnO x整体式催化剂,通过X射线衍射、X射线能谱分析、氢气-程序升温还原、X射线光电子能谱、拉曼光谱和碳烟-程序升温还原等手段对催化剂进行表征,在微型固定床反应器上评价了其催化碳烟燃烧性能,通过等温动力学实验探究了催化剂的本征活性。结果表明,Co 3O 4@MnO x催化剂呈现了以Co 3O 4为核、以MnO x为壳的核壳结构。与催化剂Co-NW相比,Co 3O 4@MnO x催化剂中Co 3O 4与MnO x之间的相互作用使其表面产生了更多高价物种Mn 4+和Mn 3+以及更多的表面氧空位,其氧化还原性能提高,催化剂的活性氧物种数量增加了两倍,催化性能得到改善,在NO存在的反应气氛中... 相似文献
4.
以氨水和氢氧化钾水溶液为沉淀剂,利用沉淀-固相热解法和中压水热-固相热解法,制备了不同形貌的Co 3O 4纳米微粉.在水热条件下,得到了立方和六角片状的Co 3O 4微粉,采用XRD和TEM等手段跟踪反应过程并表征产物,在此水热反应体系中影响产物Co 3O 4形貌的主要因素是pH值和NO 3-. 相似文献
5.
MOFs材料作为一类新型的锂离子电池电极材料而受到广泛关注和研究. 作者通过溶液扩散法将Co 3(HCOO) 6原位负载在 rGO(还原氧化石墨烯)上制备出Co 3(HCOO) 6@rGO复合材料. 将Co 3(HCOO) 6@rGO作为锂离子电池负极材料,以500 mA·g -1的电流密度恒电流充放电循环 100 周后,仍然保持有 926 mAh·g -1 的比容量,亦表现出很好的倍率性能. 循环伏安和X-射线光电子能谱测试表明,Co 3(HCOO) 6@rGO材料上的Co 2+和甲酸根在充放电过程中均发生可逆的电化学反应. 对比同样采用溶液扩散法合成的 Co 3(HCOO) 6 的测试结果发现,rGO起到活化甲酸根的电化学反应的作用,同时也改善了Co 3(HCOO) 6的倍率性能. 将MOFs材料与rGO复合为优化 MOFs 材料的电池性能提供了一个新思路. 相似文献
6.
本研究通过水热合成法并结合表面浸渍过程制备了Co 3O 4/WO 3复合催化剂,采用X射线衍射(XRD)、扫描电镜(SEM)、X射线光电子能谱(XPS)、透射电镜(TEM)、紫外-可见吸收光谱等测试技术对Co 3O 4/WO 3复合物的结构组成与微观形貌进行系统表征,在室温可见光照射下研究了Co 3O 4/WO 3对甲烷转化制甲醇的催化性能。结果表明,复合Co 3O 4可显著提升甲烷光催化转化性能,最优催化剂3.0%Co 3O 4/WO 3在可见光照射2 h时的甲烷转化量为2041μmol/g,对应的甲醇产生量及其选择性为1194μmol/g和58.5%,分别为单一WO 3的4.03倍和2.39倍,优于多数文献报道的甲烷转化异相光催化剂,且具有良好的循环稳定性。结合瞬态光电流与电子顺磁共振测... 相似文献
7.
用热分解法制得不同混合比例的二元金属氧化物催化剂Co xCr 1-xO 3/2(x = 0,0.2,0.4,0.6,0.8,1),使用SEM、XRD和XPS观察表征催化剂形貌、晶型和价态,使用线性扫描伏安、阶梯波伏安和恒电位测试电极活性、过电位和稳定性. 结果表明,该Co 3O 4和绿铬矿型Cr 2O 3混合物形成固溶体Co xCr 1-xO 3/2. x = 0.2时,Co 0.2Cr 0.8O 3/2电极性能较单一Co 3O 4和Cr 2O 3电极好,在高电位(1.0 V vs. Ag/AgCl),其电流强度是Co 3O 4的3.75倍,Cr 2O 3的15.2倍,其过电位(η = 0.0703 V)也较Co 3O 4(η = 0.6109 V)和Cr 2O 3(η = 0.435 V)小,催化性能最好,在强碱性溶液(pH=13)中有良好的稳定性. 相似文献
8.
通过水热处理Co(NO 3) 2与(NH 4) 2S 2O 8合成了CoOOH多面体, 再经高温煅烧得到具有介孔结构的Co 3O 4多面体; 利用扫描电子显微镜(SEM)、 透射电子显微镜(TEM)、 X射线衍射(XRD)和N2吸附\|脱附实验等手段对其结构和组成进行了表征; 研究了反应时间、 反应温度及(NH 4) 2S 2O 8浓度等因素对CoOOH多面体形貌的影响, 分析了CoOOH多面体的形成机理. 性能测试结果表明, 该介孔Co 3O 4多面体具有良好的葡萄糖电化学检测活性, 检测线性范围为0.05~1.8 mmol/L, 响应灵敏度为148 μA·cm -2·mmol·L -1, 检出限为1 μmol/L. 相似文献
9.
以LiOH•H 2O, Ni 2O 3, Co 3O 4和MnO 2为原料, 经过机械活化后在空气气氛下经高温烧结, 合成了锂离子电池正极材料Li[Li 0.2Mn 0.54Ni 0.13Co 0.13]O 2. 通过X射线衍射(XRD)、扫描电子显微镜(SEM)和电化学性能测试对所得样品的结构、形貌及电化学性能进行了表征. 结果表明, 900 ℃下烧结10 h后可获得晶粒细小均匀的层状Li[Li 0.2Mn 0.54Ni 0.13Co 0.13]O 2材料, 并具有良好的电化学性能, 在室温下以60 mA/g的电流充放电, 首次放电比容量可达到248.2 mAh/g, 循环50次后放电比容量为239.4 mAh/g, 容量保持率为96.45%. 测试了该材料的高低温循环性能. 相似文献
10.
以聚乙烯醇/醋酸钴复合纳米纤维为模板, 采用模板辅助共沉积技术制备了三维尖晶石型Co 3O 4纳米纤维/晶须分级结构. 并采用SEM, XRD对其形貌和晶型结构进行了表征. 在光催化降解亚甲基蓝(MB)性能实验中, 三维分级结构Co 3O 4表现出比纳米粒子和纤维更好的光催化性能. 这主要归因于Co 3O 4纳米线的次级结构和开放的三维网络结构有利于MB分子和氧分子的扩散和传输, 从而增强MB的光降解反应速率. 相似文献
11.
The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted
indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator
model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was
established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing
analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom.
Translated from Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997. 相似文献
12.
非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。 相似文献
13.
The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness. 相似文献
14.
Two vanilloids, (5 E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one ( 1) and 4-[3-hydroxydecyl]-2-methoxyphenol ( 2), isolated from the dried seeds of Grains of Paradise ( Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared. 相似文献
15.
针对恶臭测试的环境影响问题,提出了解决的实例方案,并对方案的要点及优缺点进行讨论,此方案在实际操作中具有较好的效果。 相似文献
16.
用氧化镁氯化镁水溶液制备了8水合氯氧化镁[nMg(OH)2·MgCl2·8H2O], 并测定了其在盐酸中的溶解热, 实验结果表明, 氯氧化镁溶解热与n值呈线性关系, 根据溶解热求出5Mg(OH)2·MgCl2·8H2O和3Mg(OH)2·MgCl2·8H2O的生成热分别为-7727.1和5888.1kJ·mol^1^-。 相似文献
17.
In this review, the research of the author in the field of colloidal systems is summarized. The factors influencing colloidal stability are systematized and analyzed. Examples are presented to illustrate the practical utilization of the theory of stability of colloids and thin films.This review was prepared on the basis of the works of the author, which were awarded the State Premium for 1991 in the field of science and technology, chemistry section.Institute of Physical Chemistry, Russian Academy of Sciences, 117915 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1708–1717, August, 1992. 相似文献
18.
Main hydration products of two cement pastes, i.e. CSH-gel, portlandite ( P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time ( th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, M o, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with ( th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with ( th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700 oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
19.
面对日益枯竭的能源危机,氢能是一种洁净、最有前景的替代能源。目前在各种制氢的方法中光催化分解水制氢的研究最多,光解水过程中催化剂最关键,本文对利用太阳能光解水的途径、提高光催化反应效率以及光催化剂的开发研究进行了综述。 相似文献
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