多巴胺改性聚吡咯衍生掺氮多孔碳材料的制备及其超电容性能

含氮聚合物材料在惰性气氛下热解能够产生掺氮多孔碳材料. 基于化学聚合法合成多巴胺(DA)改性的聚吡咯(PDA-PPy), 高温热解制备出掺氮多孔碳材料(NPC). 用傅里叶变换红外(FTIR)光谱, 拉曼光谱, X射线光电子能谱(XPS)分析和扫描电镜(SEM)研究其结构与形貌. 随着DA 与吡咯(Py)单体的摩尔比不断变化,PDA-PPy的形貌也随之改变, 进而影响NPC的超电容性能. 循环伏安和恒流充放电测试表明, 当DA与Py 单体的摩尔比为0.5时, 在0.5 A·g^-1的电流密度下, NPC的比电容可以达到210 F·g^-1, 电流密度为10 A·g^-1时, 比电容可以达到134 F·g^-1, 电容保持率为63.8%.     

三维还原氧化石墨烯/聚苯胺复合材料的制备及其超级电容性能

以制备的氧化石墨凝胶和聚苯胺纳米线为原料, 将二者按一定的质量比进行混合超声分散, 再以混合分散液为前驱体采用一步水热法制备得到三维还原氧化石墨烯(RGO)/聚苯胺(PANI) (RGP)复合材料, 采用扫描电镜(SEM), 透射电镜(TEM), X射线衍射(XRD), 傅里叶变换红外(FT-IR)光谱, X射线光电子能谱(XPS)和电化学测试等分析研究了复合材料的形貌、结构和超级电容性能. 结果表明, 复合材料既保持了还原氧化石墨烯的基本形貌, 又能使聚苯胺较好地镶嵌在还原氧化石墨烯的网状结构中; 且当氧化石墨与聚苯胺的质量比为1:1时复合材料在0.5 A·g^-1电流密度下比电容可高达758 F·g^-1, 即使在大电流密度(30 A·g^-1)下其比容量仍高达400 F·g^-1,在1A·g^-1电流密度下循环1000次后比容量保持率为86%, 表现出了良好的倍率性能和循环稳定性, 其超级电容性能远优于单纯的还原氧化石墨烯和聚苯胺, 其优异的超级电容性能可归咎于二者的相互协同作用.     

氮掺杂碳片的模板诱导制备及其在超级电容器中的应用

兼具有优良的导电能力,高的比表面积和极佳的化学/机械稳定性,具有二维形貌的纳米碳材料近年来逐渐成为超级电容器电极材料的研究热点. 我们在此首次报道一种模板诱导方法以制备具有规整片状形貌的氮掺杂碳材料. 我们将作为硬模板的片状镁铝双金属氢氧化物与熔融的邻苯二胺混合后加入三氯化铁催化剂,进而通过加热使邻苯二胺聚合并碳化,随后刻蚀除去其中的氧化物成分即可以得到具有规整六边形片状氮掺杂碳材料. 通过改变碳化时的温度,可以有效的调节利用该方法所得到的氮掺杂碳片的形貌、结构、石墨化程度、氮含量以及比表面积. 更重要的是这些氮掺杂碳片在用作超级电容器电极材料时体现出优异的电化学性能,在0.5 A·g^-1的电流密度下其比容量可以达到290.0 F·g^-1的. 在1 A·g^-1的电流密度下经过10000周循环测试后,其容量仍然可以达到初始值83%.     

3D石墨烯/镍铝层状双金属氢氧化物的制备及超级电容性能

超声分散氧化石墨和聚苯乙烯微球于去离子水形成稳定分散液, 加入氨水和水合肼还原氧化石墨得到包覆石墨烯纳米片的聚苯乙烯微球, 经6 mol·L^-1 KOH碱蚀和甲苯洗脱聚苯乙烯制备3D石墨烯. 将3D石墨烯超声分散于去离子水, 然后分别以硝酸镍、硝酸铝和尿素为镍源、铝源和碱源化合物水热合成3D石墨烯/镍铝层状双金属氢氧化物复合材料. 采用红外、拉曼、X射线衍射、扫描电镜、透射电镜和恒电流充-放电测试对材料的结构、形貌及电化学性质进行研究. 结果表明, 氧化石墨被还原形成有微孔结构的3D石墨烯. 镍铝双金属氢氧化物纳米片均匀分散在3D石墨烯孔壁. 在1 A·g^-1的电流密度下, 复合材料电极的比电容为1054.8 F·g^-1. 当电流密度增加到8 A·g^-1时, 比电容为628.1 F·g^-1. 循环充-放电1000次后, 比电容仍保持在97%以上, 呈示该复合材料具有优异的电化学性能.     

自支撑柔性氮掺杂碳织物电极的制备与性能研究

本文以纯棉织物为基底,吡咯单体为氮源,采用简单的原位聚合-高温煅烧的方法制备了自支撑柔性氮掺杂织物（N-CT）. 利用傅立叶红外技术、X射线光电子能谱、比表面积测试、扫描电子显微镜对所得产物进行结构与形貌表征. 结果表明,碳化后聚吡咯主要以纳米碳球包覆在碳织物表面,N-CT电极的比表面积为495.0 m²·g^-1,其含氮量为2.26%. 电化学测试表明,在0.5 A·g^-1的电流密度下N-CT电极的比电容器为256.2 F·g^-1,经过5000次的恒流充放电循环后电容保持率为98.3%,库伦效率保持率在98.8%左右,具有良好的柔性和机械性能.     

离子液体辅助条件下由稻壳合成超级电容器用多孔炭

本文以稻壳为碳源,以离子液体1-丁基-3-甲基咪唑六氟磷酸盐(BMIMPF₆)为模板和辅助活化剂制备了多孔炭材料（PCs）. 多孔炭的比表面积达1438 m²·g^-1,总孔容达0.75 cm³·g^-1. 以PCs为超级电容器电极材料,6 mol·L^-1的KOH溶液为电解液组装成扣式电池,在0.05 A·g^-1的电流密度下,比电容高达256 F·g^-1;当电流密度增大至10 A·g^-1,其比电容仍保持在211 F·g^-1,展现出好的倍率性能. 所得的多孔炭电极均表现出优异的循环稳定性. 这一工作以BMIMPF₆作为模板和辅助活化剂,为合成生物质基超级电容器用多孔炭提供了一种新方法.     

双钙钛矿La2CoNiO6无机纳米纤维的制备及超级电容器性能

以聚乙烯吡咯烷酮/硝酸镧-乙酸钴-乙酸镍(PVP/LCN)为前驱体, 采用静电纺丝法, 经预氧化、碳化, 制得双钙钛矿La₂CoNiO₆无机纳米纤维超级电容器电极材料. 利用X射线衍射(XRD)、扫描电镜(SEM)和透射电镜(TEM)对其形貌和结构进行表征. 结果表明, 纤维由菱形结构的La₂CoNiO₆纳米颗粒相互连接而成, 呈链状空间网状结构. 循环伏安(CV)、恒流充放电(CP)和循环寿命测试表明, La₂CoNiO₆纳米纤维电极材料在三电极体系中, 电流密度为0.25 A·g^-1时, 比电容值达335.0 F·g^-1; 在对称型双电极体系中, 电流密度为0.25 A·g^-1时, 比电容值可达到129.1 F·g^-1,表现出良好的电容性能.     

阳极氧化/GCD新工艺法制备镍基超级电容器薄膜电极

采用磷酸阳极氧化法在金属镍表面形成阳极氧化复合膜,在1 mol·L^-1氢氧化钾溶液中进行大电流密度恒流充放电(GCD)处理, 使基体表面形成一层多孔纳米花瓣状膜. 采用扫描电镜(SEM), X射线光电子能谱(XPS), X射线衍射(XRD)仪, 对膜的形貌、组成和结构进行了表征, 使用电化学工作站、电池寿命测试仪对该膜的电容特性进行了测试. 结果表明, 所制氧化膜由三维多孔纳米花瓣状的NiO、α-Ni(OH)₂和β-Ni(OH)₂构成, 该膜具有优异的电容特性, 其在电流密度为6.7 A·g^-1时,比电容量达1509 F·g^-1, 而当电流密度为66.7 A·g^-1时,比电容量为1120 F·g^-1 (为6.7A·g^-1时的74%).在电流密度为66.7 A·g^-1时, 经过2000次循环测试后比电容量基本保持不变.     

碳纳米管/五氧化二钒空心球的制备及其电化学性能研究

采用溶剂热法制备了碳纳米管穿插的分级结构五氧化二钒空心球（VOC_x）. 使用XRD、SEM、循环伏安曲线和充放电曲线研究了不同碳纳米管量对产物结构、形貌和电化学性能的影响. 结果表明,碳纳米管的加入明显改善了VOC的倍率特性. 碳纳米管含量为7.1%时,0.5 A·g^-1电流密度下,其比电容达到346 F·g^-1,8 A·g^-1电流密度时,其电容保持率可达75%. 与活性炭组装成混合电容器,在功率密度为700 W·kg^-1时,能量密度达12.6 Wh·kg^-1.     

氢氧化镍纳米线/三维石墨烯复合材料的制备及其电化学性能

采用水热法制备了氢氧化镍纳米线/三维石墨烯复合材料及作为比较的三维石墨烯、氢氧化镍纳米线、还原氧化石墨烯和氢氧化镍纳米线/还原氧化石墨烯, 通过X射线衍射、扫描电镜、热失重分析和氮气吸脱附表征了材料的形貌、结构和组成, 并采用循环伏安法和恒电流充放电测试了复合材料的电化学性能. 结果表明: 氢氧化镍纳米线/三维石墨烯复合材料中直径为20-30 nm的氢氧化镍纳米线和三维结构的石墨烯紧密结合, 相互交联形成网状结构, 其比表面积达到136 m²·g^-1, 孔径分布20-50 nm, 氢氧化镍纳米线的含量达到88% (w,质量分数). 在6 mol·L^-1的KOH电解液中, 复合材料的比电容在1 A·g^-1电流密度下达到1664 F·g^-1, 在1 A·g^-1电流密度下循环3000 次后的比电容保持率为93%. 将复合材料的比电容和循环性能与氢氧化镍纳米线、氢氧化镍纳米线/还原氧化石墨烯、三维石墨烯和还原氧化石墨烯的性能进行比较, 发现三维石墨烯较还原氧化石墨烯具有更高的比表面积和三维多孔结构, 可以更大地提高活性物质的利用率, 进而提高复合材料的比电容和稳定性.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.