磷化镍/氮磷共掺杂碳负极材料的制备及其电化学性能研究

以离子液体为碳源和氮源、次亚磷酸钠为磷源、乙酸镍为镍源,一步法制备了磷化镍/氮磷共掺杂碳(Ni₂P/NPC)复合材料。SEM、TEM等检测结果表明Ni₂P纳米颗粒在N、P共掺杂碳骨架上均匀分布。将所制备Ni₂P/NPC作为锂离子电池负极材料时,Ni₂P/NPC电极在0.1、0.5、1、3和5 A·g^-1电流密度下的放电比容量分别为377.7、 294.1、 265.4、211.7和187.5 mAh·g^-1。当电流密度重新回到0.1 A·g^-1,放电比容量为368.1 mAh·g^-1。电极结构在大倍率下可以保持稳定,表现出优异的倍率性能。在0.5 A·g^-1的电流密度下经200次循环后放电比容量维持在301.8 mAh·g^-1,容量保持率为80.7%,CV曲线证实Ni₂P/NPC在储锂过程中是由扩散过程和电容行为共同控制。     

磷化镍/氮硫双掺杂石墨烯复合材料的制备及电催化析氢性能

采用水热法合成了具有高活性的磷化镍纳米晶(Ni₂P), 并合成了氮、 硫共掺杂石墨烯负载磷化镍纳米催化剂(Ni₂P/NSRGO). 对该催化剂的结构和形貌进行了表征, 并研究其电催化析氢性能. 电化学测试结果表明, Ni₂P/NSRGO复合电催化剂的析氢性能优于Ni₂P/RGO催化剂, 具有较小的Tafel斜率(35 mV/dec)、 较低的过电位(η₁₀=140 mV)和良好的稳定性.     

基于钴酸锂载体构筑高体积比容量硫基复合材料

锂-硫电池具有高的理论质量/体积能量密度,因而成为最具发展潜力的高比能二次电池体系. 然而,由于硫载体通常采用轻质的碳纳米材料,导致硫基复合材料的振实密度和体积比容量均偏低,制约了电池体积能量密度的提升. 本文尝试采用具有高密度特征的钴酸锂(LiCoO₂)作为硫的载体材料,以构筑高振实密度的硫基复合材料,进而提高硫正极的体积比容量. 研究显示,LiCoO₂对可溶性多硫化物具有较强的吸附作用,能够促进硫的电化学转化,因而提高了硫的活性物质利用率和循环稳定性. 同时,由于具有高的振实密度(1.90 g·cm^-3),S/LiCoO₂复合材料的首周体积比容量高达1750.5 mAh·cm^-3,是常规硫/碳复合材料的2.2倍. 因此,本文利用具有高密度特征的LiCoO₂作为硫载体来提升硫复合材料的体积比容量,有助于实现锂-硫电池的高体积能量密度.     

基于有机磷酸类MOFs前驱体制备Ni2P/C复合材料

以镍为金属中心、 对二甲苯二磷酸为有机配体, 构筑了一种有机磷酸类Ni-MOF前驱体, 再经过一步碳化, 原位制备出多孔碳包覆Ni₂P纳米颗粒的复合材料. 该复合材料保留了前驱体的片状形貌, 比表面积可达202 m²/g, 复合材料中的Ni₂P纳米颗粒具有良好的结晶度, 颗粒均匀且无团聚现象. 在锂离子电池性能测试中, 该Ni₂P/C复合结构在缓解材料体积膨胀的同时提高了材料的电子和离子电导率, 进而提高了材料的电化学性能. 在0.2 C的电流密度下, 材料首次充、 放电比容量分别为247和226 mA·h·g^-1, 库仑效率可达91.7%, 循环200圈后, 库仑效率接近100%.     

Co金属有机骨架模板制备NiCo水滑石/泡沫镍复合材料及电容性能

通过两步法先在泡沫镍(nickel foam,NF)上原位生长Co金属有机骨架(Co metal-organic framework,Co-MOF)纳米片阵列,再浸入不同浓度Ni²⁺离子溶液刻蚀Co-MOF纳米片,在NF表面得到NiCo水滑石(NiCo layered double hydroxide,NiCo-LDH)。NiCo-LDH/NF继承了Co-MOF纳米片结构形成一级纳米片阵列,并在一级纳米片表面形成次级纳米片褶皱。在2 mmol Ni(NO₃)₂·6H₂O溶液中刻蚀得到的NiCo-LDH/NF表现出高容量、高倍率性能,在电流密度为5 mA·cm^-2时比电容为7 764.5 mF·cm^-2,电流密度为20 mA·cm^-2时比电容为6 098.2 mF·cm^-2,容量保持率为78.5%,在20 A·g^-1电流密度下经过5 000次长循环后,容量保持率为85.9%。与活性炭组装的混合...     

磷化镍催化剂的制备机理及其加氢脱氮性能

采用热重-质谱联用技术研究了次磷酸盐在氮气中的热分解过程,探讨了次磷酸盐热分解法制备磷化镍的反应机理:次磷酸镍中的Ni²⁺能够"催化"H₂PO₂^-低温发生歧化反应生成PH₃,继而还原Ni²⁺得到Ni₂P。制备了不同负载量的Ni₂P/SiO₂催化剂,用X射线衍射(XRD)、低温N₂吸附-脱附、高分辨透射电镜(HRTEM)等分析技术对催化剂结构进行表征。结果表明,Ni₂P活性组分在SiO₂载体上具有良好的分散性,颗粒粒径为5～8 nm。以喹啉为加氢脱氮模型化合物,在高压微型固定床反应器上对催化剂活性进行评价,在反应温度为360℃、氢气压力为2.0 MPa、液时空速为2.0 h^-1、氢油体积比为500:1时,Ni₂P(20%)/SiO₂催化剂的加氢脱氮率为41.5%。     

LiNbO3负极薄膜电化学性能及全固态薄膜锂离子电池应用

全固态薄膜锂离子电池具有易微型化与集成化等优点,因此,非常适合为微系统供电。负极对全固态薄膜锂离子电池的性能有重要影响。现有电池通常采用金属锂作为负极,然而其枝晶生长问题及低的热稳定性限制了相应电池在工业、军事等高温、高安全场合应用。为此,本文系统研究了LiNbO₃薄膜的电化学性能,结果表明:LiNbO₃薄膜呈现高比容量(410.2 mAh·g^-1)、高倍率(30C时比容量80.9 mAh·g^-1)和长循环性能(2000圈循环后的容量保持率为100%),以及高的室温离子电导率(4.5×10^-8 S·cm^-1)。在此基础上,基于LiNbO3薄膜构建出全固态薄膜锂离子电池Pt|NCM523|LiPON|LiNbO₃|Pt,其展现出较高的面容量(16.3μAh·cm^-2)、良好的倍率(30μA·cm^-2下比容量1.9μAh·cm^-2)及长循环稳定性(300圈循环后的容量保持率...     

Ni3S2@碳纳米管复合材料的制备及其储钠性能

采用一步固相煅烧工艺制备了碳纳米管原位封装Ni₃S₂纳米颗粒（Ni₃S₂@CNT）,并研究了其作为钠离子电池（SIBs）负极材料的电化学性能. 通过X射线衍射（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、循环伏安测试、恒流充放电以及交流阻抗等研究了Ni₃S₂@CNT的物相结构、形貌特征以及电化学性能. 电化学测试表明,材料在100 mA·g ^-1电流密度下,放电容量可以达到541.6 mAh·g ^-1,甚至在2000 mA·g ^-1的大电流密度下其放电比容量也可以维持在274.5 mAh·g ^-1. 另外,材料在100 mA·g ^-1电流密度下,经过120周充放电循环后其放电和充电比容量仍然可以保持在374.5 mAh·g ^-1和359.3 mAh·g ^-1,说明其具有良好倍率性能和循环稳定性能. 良好的电化学性能归因于这种独特的碳纳米管原位封装Ni₃S₂纳米颗粒结构. 碳纳米管不但可以提高复合材料的导电性,也可以缓冲Ni₃S₂纳米颗粒在反复充放电过程中产生的体积膨胀效应,明显改善了Ni₃S₂@CNT负极复合材料的电化学性能.     

Ni2P/Cu(OH)2催化剂的制备及其全解水性能研究

通过化学处理法在泡沫铜基底表面生成Cu(OH)₂纳米线,大大增加了基底材料的表面积和导电性.采用水热法在Cu(OH)₂纳米线表面制备片状Ni-CH/Cu(OH)₂前驱体,对Ni-CH/Cu(OH)₂前驱体进行低温磷化得到多级结构Ni₂P/Cu(OH)₂催化剂.通过扫描电子显微镜(SEM)、X射线光电子能谱仪(XPS)和X射线衍射仪(XRD)对催化剂的物质结构和表面形貌进行了表征.采用线性伏安法、恒电位等技术对催化剂的电化学性能进行测试.在1.0 mol·L^-1 KOH碱性溶液中,当电流密度为10 mA·cm^-2时,Ni₂P/Cu(OH)₂的析氢反应(HER)和析氧反应(OER)过电位分别为133和333 mV,且均具有较好的稳定性.将这种多级结构Ni₂P/Cu(OH)₂催化剂分别用作阳极和阴极进行全解水电解,电流密度达到10 ...     

不同半导体体系中磷化镍光催化甲酸分解的助催化作用

研究了在不同的半导体体系(TiO₂, CdS和C₃N₄)中, Ni₂P光催化甲酸(HCOOH)分解制氢的助催化效应. 作为助催化剂, Ni₂P与3种半导体形成的复合光催化剂均表现出良好的HCOOH分解制氢活性. Ni₂P/TiO₂, Ni₂P/CdS, Ni₂P/C₃N₄ 3种光催化剂最优的产氢活性分别为41.69, 22.45和47.67 μmol·mg^-1·h^-1, 分别为纯TiO₂, CdS和C₃N₄的3.8倍、 10倍和210倍, 表明Ni₂P在光催化HCOOH分解制氢体系中具有普适性. 研究了光催化HCOOH分解制氢的机理, Ni₂P的加入使光生电子从半导体转移至Ni₂P, 提高了光生电子-空穴对的分离效率; Ni₂P还促进了活性物种·OH的生成, 提高了光催化HCOOH分解的产氢速率.     

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.