氮掺杂酸角衍生多孔碳的制备及电容性能研究

随着化石燃料的加速消耗和能源危机的日益加剧,作为新型储能元件的超级电容器引起了研究人员极大的关注.本文通过水热法制备了生物质衍生多孔碳,并对该材料的微观结构和元素组成进行分析,研究了其作为超级电容器电极材料的电化学性能.结果表明,经过掺氮处理的酸角衍生多孔碳材料其比电容从166 F·g-1提高到了232 F·g-1,说明掺杂能有效提高生物质衍生多孔碳材料的电容性能.     

钠离子电池负极材料二氧化钛的氮离子掺杂改性研究

二氧化钛(TiO2)作为钠离子电池负极材料有着极大的应用前景,但是,低的电导率限制其大规模应用.通过静电纺丝的方法,制备出碳复合的锐钛矿二氧化钛(TiO2)样品,并对样品进行氮掺杂,作为自支撑钠离子电池负极材料.通过XRD、SEM、XPS、充放电测试对其进行结构、形貌分析和电化学性能研究.结果发现,氮离子成功的掺入晶体内部,且对TiO2的晶型没有影响.氮离子掺杂后,样品N-TiO2的倍率性能有了明显的提高.在10 A· g-1电流密度下,样品TiO2和N-TiO2的可逆比容量分别为134.3 mAh· g-1和212.1 mAh· g-1.在1 A· g-1的电流密度下,样品N-TiO2和TiO2的可逆比容量分别为192.4 mAh· g-1、124.5 mAh· g-1,循环1000圈后,放电比容量依然高达195.5 mAh· g-1、120.9 mAh· g-1,样品N-TiO2和TiO2均具有优异的循环稳定性,但氮离子掺杂后,比容量有了显著的提高.实验表明,氮离子掺杂后,材料中产生的Ti3+和氧空位可以提高电子电导率和Na+在材料中的扩散效率,使得其电化学性能有了明显的改善.     

三维还原氧化石墨烯的制备及超级电容性能

以氧化石墨凝胶制备的氧化石墨烯溶胶为前驱体,一步水热法制备三维还原氧化石墨烯,采用XRD、Raman、XPS、SEM和TEM对其结构和形貌进行表征;将其作为超级电容器的电极材料时,采用直接压片法制备工作电极,在三电极体系中测试了材料的超级电容性能.结果表明:经一步水热法对氧化石墨烯溶胶进行还原处理,可去除结构中大部分的含氧官能团,所得三维还原氧化石墨烯呈多孔网状结构,层数为3～7层;比电容在0.5A·g-1的电流密度下可达294 F·g-1,且在1A·g-1电流密度下循环1000次后仍高达247 F·g-1,保持率为88.85;;欧姆电阻Rs约为0.52 Ω,界面电阻Rc约为1.53 Ω.相对于热还原法和化学还原法所制备的石墨烯材料具有更好的超级电容性能.     

椰壳活性炭孔结构的调节及对超电容性能的影响

以椰壳为原料采用化学活化法制备活性炭,通过改变碱炭比,得到不同比表面积和孔结构的活性炭材料,并进行机理研究.其中,高比表面积产生大量容量;大量介孔为离子快速转移提供通道,有利于提高超电容的倍率性能.以6 mol·L-1的KOH为电解液组装成对称电极的超级电容器,并进行电化学性能测试.制备的AC-4活性炭比表面积为3831 m2·g-1,介孔率42.8;,组装为超级电容器在1A·g-1电流密度下放电比容量达到260F·g-1,100A ·g-1时仍保持216.116 F·g-1,最高功率密度24.5 kW· kg-1,能量密度13.35Wh· kg-1.     

微波辅助水热合成条件对直接合成纳米HZSM-5晶体性质的影响

利用微波辅助水热合成法直接制备了纳米HZSM-5晶体.采用XRD、FT-IR、SEM、BET和NH3-TPD等手段对合成样品进行了分析表征,研究了晶化温度和时间对合成产物晶体性质的影响.结果表明,晶化温度和时间对微波辅助水热直接合成产物微观形貌、晶粒尺寸和分散度影响明显.较低的晶化温度和较短的晶化时间均难以形成形貌规则的HZSM-5晶体.随着晶化温度的升高,合成样品逐渐变为球形晶粒、晶粒尺寸逐渐增大、分散度逐渐提高,继续提高晶化温度达180 ℃时,晶粒长大使比表面积稍有降低;随着晶化时间的延长,样品的微孔和介孔增多,比表面积和孔容逐渐增大,继续延长晶化时间,晶体内微孔可能的收缩和晶粒的长大使得样品孔容和比表面积减小.160 ℃和1.5 h条件下制备的HZSM-5分子筛晶体形貌呈球形,晶粒尺寸约为60 nm,分散程度较好;其比表面积、孔容和平均孔径分别为398.45 m2·g-1、0.63 cm3·g-1和6.27 nm;晶体表面具有弱酸特征.     

氧化还原法制备氧化锰超级电容器电极材料

以高锰酸钾(KMnO4)和聚乙烯吡络烷酮(PVP)为原料,采用氧化还原法制备介孔氧化锰.研究发现,产物的晶型和微观结构受KMnO4溶液浓度的影响.当KMnO4溶液浓度从0.1 mol·L-1增加到0.3 mol·L-1,产物从比表面积13.6 m2·g-1的晶态Mn3O4转变成比表面积约60 m2·g-1的非晶态MnO2.电化学测试表明:非晶MnO2具有最佳电化学性能,在2 mol·L-1 KOH溶液中,1 A·g-1的电流密度下的比电容可达442 F·g-1,5 A·g-1的电流密度下循环1100次后比电容保有率为72.6;.     

氮掺杂多孔晶态碳的合成及其电容特性的应用

采用水热-活化法以葡萄糖为碳源、尿素为氮源合成出高含氮量的多孔晶态碳材料.采用透射电镜、X射线衍射、N2吸附-脱附和X射线光电子能谱对材料的结构进行表征;利用循环伏安、恒流充放电和电化学阻抗对材料进行电容性能的测试.结果表明:合成材料具有强的结晶性、大的比表面积(1567 m2/g)、和高的氮含量(7.97at;).当其做为电极材料应用于超级电容器中时,其展示出良好电化学性能,在1 A/g时,其比电容为258 F/g,要远高于含氮的活性碳(222F/g)和晶态碳(106F/g)的电容;5000次循环后,其比电容保持率为99.98;;在功率密度为500W/kg下其能量密度为10.69 Wh/kg.     

醇-水体系中pH值和焙烧温度对合成MgO纳米片晶体性质的影响

采用液相法,在醇-水体系中,以Mg(NO3)2·6H2O为镁源、PEG-2000为表面活性剂、NH3·H2O为沉淀剂,研究了pH值和焙烧温度对制备MgO纳米片晶体性质的影响.采用XRD、SEM和BET等手段对MgO纳米片晶相组成、微观形貌、孔结构进行分析表征.研究结果表明,pH值和焙烧温度对MgO纳米片晶相组成没有影响,但对样品微观形貌和比表面积影响较大.较低的pH值和焙烧温度或者较高的pH值和焙烧温度均会导致样品形状不规则,出现不同程度团聚,比表面积较小.在pH=10、焙烧温度500℃条件下制得MgO纳米片形状规整、分散性较好,比表面积、孔容和平均孔径分别为145.42 m2·g-1、0.67 mL·g-1和18.56 nm.     

焙烧温度对Li[Mn1/3Ni1/3CO1/3]O2结构及电化学性能影响

采用碳酸盐共沉淀法制备了Li[Mn1/3Ni1/3Co1/3]O2,研究了前驱体的焙烧温度对材料结构和电化学性能的影响.XRD测试结果表明,800℃下焙烧得到的样品具有较好的层状结构和较低的阳离子混排程度.SEM测试表明合成材料具有球状形貌,平均粒径可达5μm,组成它的一次颗粒粒径平均为200nm.在2.8～4.3V(vs.Li/Li+)0.2C条件下进行充放电测试,800℃下合成的样品的首次放电比容量最高(159.06mAh·g-1),容量损失最小,循环50次后能保持初始放电比容量的95.7;.EIS分析结果表明,800℃焙烧的样品的电化学活性最好.     

临江高品位硅藻土的物理化学提纯

采用超声、酸浸和煅烧结合的物理化学法对临江高品位硅藻土进行处理,分析不同的硫酸浓度、酸浸处理方式(水浴、水热)以及煅烧温度对其形貌、比表面积、吸附量及各成分含量的影响,并利用红外光谱仪分析了硅藻土提纯前后谱图的变化,最终确定了最佳酸浸和煅烧提纯条件.其中,水浴酸浸采用28;硫酸处理后500℃煅烧,精硅藻土比表面积值为27.79 m2·g-1,非晶质SiO2含量为93.42;,对罗丹明B吸附量为1.94 mg·g-1;水热酸浸采用28;硫酸处理后500℃煅烧,精硅藻土比表面积值为25.10 m2·g-1,SiO2含量93.52;,对罗丹明B吸附量为1.84 mg·g-1.     

Triethyl ammonium salt of O,O′-bis(p-tolyl)dithiophosphate, [Et3NH]+[(4-MeC6H4O)2PS2]−

Triethyl ammonium Salt of O,O′-bis(p-tolyl)dithiophosphate and O,O′-bis(m-tolyl)dithiophosphate have been obtained by reaction of p- and m-cresol, respectively with P₂S₅ in toluene and have been characterized by elemental analysis, IR, ¹H and ³¹P NMR spectroscopy. The molecular structure of O,O′-bis(p-tolyl)dithiophosphate has been determined. Crystal data: [Et₃NH]⁺[(4-MeC₆H₄O)₂PS₂]⁻: Monoclinic, P2₁/c, a=15.2441(9) ?, b=10.415(2) ?, c=3.9726(9) ?, β=91.709(7)°, V=2217.5(1) ?⁻³, Z=4.Supplementary materials Additional material available from the Cambridge Crystallographic Data Centre (CCDC no. 600927 for [Et₃NH]⁺[(4-MeC₆H₄O)₂PS₂]⁻ comprises the final atomic coordinates for all atoms, thermal parameters, and a complete listing of bond distances and angles. Copies of this information may be obtained free of charge on application to The Director, 12 Union Road, Cambridge CB2 2EZ, UK (fax: +44-1223-336033; email: deposit@ccdc.cam.ac.uk or www:http://www.ccdc.cam.ac.uk).     

First-principles coexistence simulations of supercooled liquid silicon

We perform first-principles coexistence simulations of the low-density and the high-density phases of supercooled liquid silicon and find a negative slope for the coexisting line in the temperature-pressure plane. Electron density maps and electron-localization function plots of the two phases of silicon show marked differences. The calculated differences suggest more localized electrons in the low-density liquid compared to the high-density liquid, coming from an increased population of covalent bonds, which further explain the calculated negative slope in the two phase coexistence regime. This is consistent with the presence of a pseudo-gap in low-density liquid silicon, absent in the high-density liquid which shows a metallic behavior.     

Crystal structures of thecis andtrans isomers of dithiahexahydro[3.3]metacyclophane

Structures of both thecis andtrans isomers of dithiahexahydro[3.3]metacyclophane, ?C₆H₄?CH₂SCH₂?C₆H₁₀?CH₂SCH₂?, have been determined, wherecis andtrans refer to the attachments to the cyclohexane ring. Thecis form crystallizes in the monoclinic space groupP2₁/c witha=8.4299(11)Å,b=21.772(2)Å,c=8.9724(13)Å, β=116.574(11)^o, andZ=4. Thetrans isomer packs into the monoclinic space groupP2₁ witha=8.159(16)Å,b=10.185(5)Å,c=9.558(2)Å, β=112.435(18)^o, andZ=2. The cyclohexane ring of thecis isomer is in the chair conformation, while the cyclohexane of thetrans isomer is found in a twisted boat conformation.     

CTAB与SDBS对碳酸锶粒子生长形态调控及机理研究

以表面活性剂CTAB和SDBS为化学添加剂,采用化学共沉淀法对碳酸锶晶体的生长形态进行调控,成功地制备出了实心的树枝状和花瓣为空心的花状碳酸锶粉体,并用X射线衍射(XRD)、扫描电子显微镜(SEM)和傅里叶变换红外光谱(FT-IR)等分析手段对样品进行了表征;最后重点对化学添加剂可能产生的影响机理进行了初步的探讨.结果表明,CTAB和SDBS在晶体生长的过程中能起到显著的影响作用,两者对粒子分散性能的作用效果相反,而且后者对晶体(013)和(213)晶面表面能降低的贡献明显大于前者.     

Crystal structures of the cis and trans isomers of a tetrathia[3.3.3.3]cyclophane

Both the cis and trans isomers of 3,11,18,26-tetrathiatricyclo[26.2.2.1^5,9.2^13,16.1^20,24] hexatriaconta-5,7,9,20,22,24-hexene have been prepared and structurally characterized. Each of these centrosymmetric tetrathia dimers includes two cyclohexane rings in chair conformations with either 1,4-cis or 1,4-trans bonding and two meta-substituted benzene rings. The cis isomer packs into the monoclinic space group P2₁/a with a = 10.485(3)Å, b = 10.3956(18)Å, c = 14.1343(10)Å, = 105.200(13)°, Z = 2 and refined to an R factor of 0.046. The trans isomer crystallizes in the monoclinic space group P2₁/c with a = 10.7217(12)Å, b = 5.6797(7)Å, c = 25.415(5)Å, = 96.001(12)°, Z = 2 and refined to an R factor of 0.043. In the cis structure each benzene ring faces a cyclohexane ring while in the trans structure the cyclohexane rings face one another.     

Crystal structure of Zn4Na(OH)6SO4Cl·6H2O

The structure of Zn₄Na(OH)₆SO₄Cl·6H₂O, a secondary mineral from Hettstedt, Germany, was determined by single-crystal X-ray diffraction. The crystals are hexagonal,a=8.413(8),c=13.095(24) Å, space group $P\bar 3$ , Z=2. The structure was refined to R=0.0554 and R_w=0.0903 for 970 reflections with I≥3σ(I). The structure can be described as zinc hydroxide layers perpendicular toc, from which sulfates and chlorides extend. The layers are held together by a system of hydrogen bonds involving hexaaquo Na⁺ ions which occupy the interlayer space.     

Synthesis and Crystal Structure of 5-[2-(6-bromonaphthalenyloxymethyl)]-3-(4-morpholinomethyl)-1,3,4-oxadiazole-2(3<Emphasis Type="Italic">H</Emphasis>)-thione

Abstract  The title compound, C₁₈H₁₈BrN₃O₃S, a derivative of 1,3,4-oxadiazole, crystallizes in the triclinic space group P-1 with unit cell parameters a = 6.8731(3), b = 8.9994(4), c = 15.7099(6) ?, α = 92.779(3)°, β = 130.575(3)°, γ = 107.868(4)°, Z = 2. The dihedral angle between the mean planes of the planar naphthyl and morpholine (chair) rings with the planar oxadiazol ring is 50.1(8) and 76.8(6)°, respectively. The planar naphthyl ring is twisted 52.2(5)° with the mean plane of the morpholine ring. A group of four intermolecular close contacts are observed between a bromine atom and hydrogen atoms from the closely packed naphthyl, morpholine and oxy–methyl groups in the unit cell. These molecular interactions in concert with an additional series of π–π stacking interactions that occur between the center of gravity of the two 6-membered rings of the naphthalene group influence the twist angles of each of these three groups. A MOPAC AM1 calculation of the conformation energy of the crystal structure [226.0128(9) kcal] compared to that of the minimum energy structure after geometry optimization [29.9744(1) kcal] reveals a significantly reduced value. The twist angles of the three groups above also change after the AM1 calculation giving support to the influence of both intermolecular C–H···Br short-range interactions and Cg π–π stacking interactions on these angles which therefore play a role in stabilizing crystal packing. Graphical Abstract  Crystal structure of 5-{[(6-bromonaphthalen-2-yl)oxy]methyl}-3-(morpholin-4-ylmethyl)-1,3,4-oxadiazole-2(3H)-thione, C₁₈H₁₈BrN₃O₃S, is reported and its geometric and packing parameters described and compared to a MOPAC computational calculation. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

电沉积法制备ZnO纳米棒阵列及其发光特性

本文以掺F的SnO2导电玻璃为基板,以硝酸锌水溶液为电解液,采用三电极恒电位体系电沉积制备ZnO纳米棒阵列,系统考察了硝酸锌浓度和沉积电位等工艺参数对ZnO纳米棒阵列的微观形貌及其发光性能的影响规律.结果表明,硝酸锌浓度和沉积电位对纳米棒阵列的形貌有显著影响,控制适宜的工艺条件可以制备出直径分布均匀、结晶性好且纯度高的六方纤锌矿ZnO纳米棒阵列.荧光光谱分析表明,电沉积制备出的ZnO纳米棒阵列在385 nm附近有一个强荧光发射峰,且发光性能稳定、对纳米棒阵列微观形貌的细微变化不敏感,使其在发光二极管和激光器等领域具有广阔的应用前景.     

Crystal structure of irisolidone from the flowers of Pueraia lobata

Irisolidone (5,7-dihydroxy-6,4′-dimethoxyisoflavone) was isolated from the flowers of Pueraia lobata and its crystal structure was examined by X-ray single crystal diffraction. The crystal structure of irisolidone is monoclinic, space group P2₁/c with a = 15.491(9) ?, b = 7.895(4) ?, c = 13.321(7) ?, β = 110.546(9)° and Z = 4. Hydrogen bonding and aromatic π–π stacking assemble the title compound into a three-dimensional networking structure.