新合成方法制备的LiCoO2正极材料的结构和电化学性能研究

采用新合成方法制备了锂离子二次电池正极材料LiCoO₂。通过ICP-AES、XRD、SEM、电化学方法等测试分析了所合成材料的物理性质和电化学性能，并与商品LiCoO₂材料作了对比研究。同时分别以国产MCMB和石墨作负极活性物质、合成的LiCoO₂作正极活性物质做成锂离子电池，对其电化学性能进行了测试。实验结果表明，所合成的LiCoO₂材料的电化学性能优于其它两种商品LiCoO₂材料，其初始放电容量为155.0 mAh·g^-1，50次循环后的容量保持率达95.3%，而且以此为正极的锂离子电池也表现出优良的电化学性能。计时电位分析结果还表明，合成的材料在充放电循环过程中发生了三次相转变过程，但相变过程具有良好的可逆性。     

Li3V2(PO4)3的溶胶-凝胶法合成及其性能研究

以LiOH·H₂O、NH₄VO₃、H₃PO₄和柠檬酸等为原料采用溶胶-凝胶法合成了锂离子二次电池正极材料磷酸钒锂(Li₃V₂(PO₄)₃)。考察了煅烧温度和配位剂种类等条件对产物组成及电化学性能的影响。研究了优化条件下制得样品的循环伏安、充放电性能和循环性能。0.1 C条件下,样品首次放电比容量达129.81 mAh·g^-1，经过100次循环后容量几乎没有衰减，仍保持在128 mAh·g^-1。X射线衍射研究表明合成单一Li₃V₂(PO₄)₃晶体所需温度比固相法低；并考察了循环20次后材料充电到各个单相的晶体结构，通过X射线衍射和最小二乘法计算给出了其晶胞参数变化过程，证实了循环嵌Li过程中晶体结构能够得到重现。     

新型中温固体氧化物燃料电池阴极材料Fe掺杂Sm0.5Sr0.5CoO3性能研究

本文系统研究了新型中温固体氧化物燃料电池(IT-SOFC)阴极材料Sm_0.5Sr_0.5Co_1-xFe_xO_3－δ(SSCF)的晶体结构、热膨胀系数、导电率及电化学性能。固相合成的Sm_0.5Sr_0.5Co_1-xFe_xO_3－δ化合物均为单相材料，随着掺Fe量的不同，SSCF的晶体结构发生变化，在0≤x≤0.4时，SSCF为正交晶系钙钛矿结构，在0.5≤x≤0.9时，SSCF为立方晶系钙钛矿结构。Fe掺杂可以显著的改善Sm_0.5Sr_0.5CoO₃的热膨胀系数，随着Fe含量的增加，热膨胀系数减小。在800℃下，SSCF导电率均大于100 S·cm^-1。随着Fe含量的增加，极化电阻增大；含量x=0.4时，极化电阻达到最大值；之后，随Fe含量的增加，极化电阻减小，在700～800 ℃时，Sm_0.5Sr_0.5Co_0.2Fe_0.8O_3－δ表现出了良好的氧催化活性。     

三维花状Fe2（MoO4）3微米球的水热制备及电化学性能

以FeCl₃·7H₂O和Na₂MoO₄为原料,采用水热合成法制备三维花状Fe₂（MoO₄）₃微米球。探讨不同合成温度对样品形貌的影响,利用XRD、SEM和EDS等分析技术对样品的结构、形貌进行了表征,对该材料的电化学性能进行了测试。结果表明：Fe₂（MoO₄）₃微米球是由二维纳米片自组装而成的花状结构,合成温度为160℃时,制备的样品具有良好的电化学性能,当电流密度为100mA·g^-1,首次放电比容量为1431mAh·g^-1;并具有较好的循环性能和倍率性能。并对160℃合成样品表现较好电化学性能的原因进行了探讨。     

锂离子电池正极材料LiNi0.75-xCoxMn0.25O2的合成及电化学性能研究

以LiOH·H₂O、Ni(OAc)₂·4H₂O、Co(OAc)₂·4H₂O和MnO₂为原料，在水热反应釜中预处理，然后进行高温固相反应，合成了一系列锂镍钴锰氧化物LiNi_0.75-xCo_xMn_0.25O₂(x=0.05,0.10,0.15,0.20,0.25)。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、粒径及电化学性能进行了表征。结果表明，当x=0.20时，所合成的正极材料具有很好的α-NaFeO₂型层状晶体结构，晶胞参数a=0.286 1 nm，c=1.416 4 nm， V=0.100 4 nm³，以50 mA·g^-1的电流密度在3～4.3 V(vs Li/Li⁺)充放电时，首次放电比容量达172.5 mAh·g^-1，首次放电效率高达90.9%，30个循环后其放电比容量依然保持在161.1 mAh·g^-1。     

微量Mg/F表面梯度渗透改善高电压LiCoO2界面脆弱

采用高温固相法在1 050 ℃下烧结，制备了LiCoO₂低浓度梯度改性样品，分别为LiF掺杂包覆(LCOLF、LCO@LF)和MgF₂掺杂包覆(LCOMF、LCO@MF)。通过光电子能谱、透射电子显微镜和电化学技术等表征方法，对比分析材料形貌及电化学性能。结果表明，体相掺杂复合电极中，LCOLF热重测试显示出最优热稳定性，LCOMF晶体中(003)和(104)晶面间距收缩；45 ℃下 1C 倍率循环 70圈后，LCOLF 和 LCOMF 比容量分别为 141.45和 166.98 mAh·g^-1，循环性能优于 LiCoO₂。表面包覆复合电极中，LCO@LF和 LCO@MF晶粒表面光洁且晶格氧键价都向更高结合能方向增强；LCO@MF构建了坚实且紧密的包覆层，循环70圈后，放电比容量和容量保持率分别为 183 mAh·g^-1和 91.26%(LCO@LF分别为 154.38 mAh·g^-1和 77.54%)，循环性能显著优于体相掺杂。     

反应温度对微波水热法合成Bi2WO6粉体及光催化性能影响的研究

以Na₂WO₄·2H₂O和Bi(NO₃)₃·5H₂O为原料,用微波水热法在140~200 ℃保温1 h合成出不同形貌的正交晶相粉体。利用 XRD、FE-SEM、BET、DRS等分析手段表征了Bi₂WO₆粉体,以RhB溶液为目标降解物,对不同反应温度下合成粉体的光催化性能进行了研究,结果表明：反应温度对合成Bi₂WO₆粉体的物相、形貌及光催化性能均有较大影响,180 ℃时合成的绒线团状Bi₂WO₆粉体比表面积为25.63 m²·g^-1,禁带宽度为2.92 eV,因光在粉体催化剂内产生了漫反射,光催化效果最佳,在可见光照射下3h时RhB溶液降解率达到了96%,紫外光照射下2 h时RhB溶液降解率达到了98%以上。     

Na4Ca(SO4)3复盐高温合成及温度对晶体形貌的影响

用高温合成法制备出硫酸钙复盐Na₄Ca(SO₄)₃，利用差热分析、X射线衍射、扫描电子显微分析等现代测试仪器研究了该复盐的反应历程。研究结果表明，其反应过程按CaSO₄+Na₂SO₄→(Na_0.8Ca_0.1)₂SO₄→Na₄Ca(SO₄)₃进行。Na₄Ca(SO₄)₃为高温稳定相，其最佳合成温度为800 ℃～1 100 ℃。育晶温度及时间对复盐形貌有明显影响，在1 000 ℃保温2 h后转到945 ℃育晶5 h,晶体生长较好。     

共沉淀法制备LiMnxCoyO2的显微结构及其电化学性能

通过共沉淀法制备前驱体,随后在900 ℃下经不同时长烧结得到了层状LiMn_xCo_yO₂。X射线衍射、扫描电镜和透射电镜的研究结果表明,层状LiMn_xCo_yO₂的晶体结构是菱面体点阵,空间群是R3m,点阵常数与LiCoO₂非常接近。不同烧结时长下得到的样品在扫描电镜下均呈球状,随着烧结时间延长,球形规整度变得更好。对不同样品的电化学性能测试表明,烧结时间越长,样品中Mn的相对含量越高,其首次充放电比容量和循环性能越好。     

Ba0.4Sr0.6Co1-xFexO3-δ系阴极材料的制备和表征

采用甘氨酸-硝酸盐(GNP)法合成了中温固体氧化物燃料电池阴极材料Ba_0.4Sr_0.6Co_1-xFe_xO_3-δ(x=0.0～0.8)系列粉体。利用XRD和SEM对材料的结构和微观形貌进行分析,用直流四端子法测量了烧结陶瓷体在中温(450～800 ℃)范围内的电导率。结果表明,制备的样品为单一钙钛矿相,随着Fe含量增加,XRD衍射峰值向高角度方向稍有偏移。电导率随着温度及Fe含量的变化出现极大值,在x＜0.2时,Ba_0.4Sr_0.6Co_1-xFe_xO_3-δ系列烧结体在中温(450～800 ℃)区的电导率,随Fe掺入量的增大而增大,x=0.2样品的电导率最高,800 ℃时达244.7 S·cm^-1,远超过文献报道值,进一步增大Fe含量导电性能变差。     

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%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

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.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

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.