固体氧化物燃料电池NiO@GDC复合阳极制备及性能研究

采用溶胶凝胶法制备NiO@GDC复合阳极材料.以NiO、GDC作为阳极、YSZ为电解质、GDC为阻挡层、LSCF为阴极制备单电池,并研究不同NiO/GDC质量比对粉体形貌及单电池电性能的影响.通过XRD、SEM以及电化学工作站等测试手段分别对粉体、物相及电池的电性能进行了测试与表征.结果表明,750℃下,3; H2O+H2还原气氛下测试,阳极中NiO/GDC质量比为5∶5时单电池具有最好的电池输出性能,最高开路电压为1.08 V,功率密度是0.4 W/cm2,极化电阻是1.0 Ω·cm2.     

原料NiO粉末对燃料电池Ni/SDC阳极材料微结构和性能的影响

分别采用商用氧化镍和煅烧碱式碳酸镍所得氧化镍粉末与Ceo.8Smo.2O2-δ(SDC)粉末混合,经压制烧结制得燃料电池NiO/SDC阳极烧结体,经H2还原后得到Ni/SDC金属陶瓷阳极材料,考察了不同NiO原料和加入量对阳极烧结体和阳极材料的微结构及相关性能的影响,还对以Ni/SDC为阳极构建的燃料电池单电池的性能进行了测试.实验结果表明:煅烧碱式碳酸镍所得NiO粉末和商用NiO粉末的平均粒径分别约为1.1 μm和8μm,前者更为均匀细小;由煅烧碱式碳酸镍所得NiO所制备的Ni/SDC阳极材料具有更高的电导率,含40; NiO的阳极材料(S-Ni/40SDC),在H2气氛中的电导率可达117.5 S·cm-1.以煅烧碱式碳酸镍所得的NiO制备的NiO/SDC为阳极,SDC为电解质,(Y0.5Ca0.5) BaCo3ZnO7-50SDC为阴极的单电池在700℃下的最大输出功率达225 mW/cm2,开路电压为0.85 V,电池性能优于以商用NiO为阳极原料所构建的单电池.     

核壳结构的LSCF-GDC复合阴极的合成研究

采用静电纺丝技术制备结构均一的LSCF纤维,再利用溶胶法在纤维表面包裹一层GDC纳米粉体,构建核壳结构的LSCF-GDC复合阴极.运用DTA-TG、XRD、SEM、EDS和电化学工作站等测试手段分别对静电纺丝纤维的热性能、物相组成、粉体及单电池的形貌、阴极成分和单电池的电性能等进行了表征.研究结果表明,通过静电纺丝法可以制备纳米级LSCF纤维.该纤维经过800℃烧结后,形成直径在150～200 nm长度超过100μm的LSCF纤维.以Ce(NO3)3·6H2O、Gd(NO3)3·6H2O溶胶作为原料,与LSCF混合可以制备具有核壳结构的LSCF-GDC复合材料.该材料与通过涂刷烧结的方式可以在GDC//GDC+NiO半电池表面制备具有纤维结构的多孔阴极.制备后的电池为LSCF-GDC//GDC//GDC+NiO结构,该单电池在700℃下,以H2为燃料,空气为氧化气的最大功率密度为0.64 W/cm2,极化阻抗为0.04Ω·cm2.     

水热反应温度对碱性条件下TiO2纳米晶生长动力学及其光电性能的影响

以钛酸丁酯为原料,在碱性条件下水热合成了锐钛矿相TiO2纳米晶.采用X射线衍射仪、比表面积测试仪、扫描电子显微镜等方法对纳米晶粒的晶体结构、比表面积以及光阳极的表面形貌分别进行表征,研究水热反应温度对TiO2纳米晶生长动力学过程的影响规律.结果表明:随着温度的升高,锐钛矿相纳米晶的平均晶粒尺寸先增大后减小.光电转换性能测试表明,电池的光电转换性能随着水热反应温度的升高而增大,在220℃时获得最大光电转换效率4.05;( 1sun,100 mW/cm2).并分析了水热反应温度对碱性条件下TiO2纳米晶粒的生长动力学过程和电池光电转换性能的影响机制.     

低温超晶格YSZ/STO/YSZ电解质薄膜的制备及表征

采用脉冲激光沉积法(PLD),在Al2O3 (ALO)衬底上,将Y2O3∶ZrO2(YSZ)和SrTiO3 (STO)按照YSZ/STO/YSZ的顺序依次沉积,形成超晶格YSZ/STO/YSZ电解质薄膜,利用SEM、XRD和交流阻抗对其形貌、相结构和电学性能进行了表征.结果表明,衬底温度为700℃形成的超晶格YSZ/STO/YSZ电解质薄膜颗粒大且均匀,排列紧密且呈规律圆柱状;YSZ、STO均沿(111)方向择优生长;低温时电导率比单层YSZ电解质薄膜高出4个数量级,是较为理想的低温固体燃料电池电解质.     

TiO2纳米团聚体的制备及在太阳电池中的应用

利用钛酸四丁酯水解反应,结合溶胶-凝胶与水热处理法制备了TiO2纳米团聚体.以该团聚体制备染料敏化太阳电池的光阳极,不但可以保持纳米粉体高比表面积的优点,同时可以提高对太阳光的散射率,简化电池制备工艺.本文研究了水解pH值对粉体物理性质、电池效率的影响规律.结果表明,水解的pH值对TiO2纳米粒子的尺寸、分布以及染料敏化太阳电池光阳极的显微形貌、电池光电特性都有很大影响.当pH值为1时,制备的电池效率最高达到5.77;(Jsc=15.04 mA/cm2,Voc=0.73 V, FF=0.53).     

聚丙烯酸电解质准固态染料敏化TiO2太阳能电池

以聚丙烯酸为电解质取代传统的液体电解液制备了准固态染料敏化TiO2太阳能电池.该电池具有较好的光电转换性能,在60mW/cm2的模拟光照下(AM1.5),短路电流Isc和开路电压Voc分别为91.5μA/cm2和520mV,光电转换效率和填充因子分别为0.06;和0.63.     

PEDOT:PSS/ZnPc作为有机小分子太阳电池阳极修饰层的研究

采用阳极修饰法构建了基于酞菁铜(CuPc)和碳60(C60)的有机小分子太阳电池,分别研究了酞菁锌(ZnPc)、聚苯乙烯磺酸(PEDOT:PSS)和PEDOT:PSS/ZnPc作为阳极修饰层对该有机太阳电池输出性能的影响,并对三种修饰层的相关机理进行了探讨.结果表明:加入ZnPc修饰层的电池开路电压(Voc)增大,从0.372提高到0.479 V.旋涂PEDOT:PSS的电池短路电流(Jsc)提高,由1.943 mA/cm2提高到3.752 mA/cm2.而以PEDOT:PSS/ZnPc作为阳极修饰的电池Voc和Jsc均有较大的提高,Voc从 0.372 V提高到0.482 V,Jsc从1.943 mA/cm2提高到3.810 mA/ cm2,其转换效率可提高两倍以上.分析认为,ZnPc更有利于阳极空穴的输出,PEDOT:PSS能有效改善ITO表面的平整度的性质是提高太阳电池性能的主要原因.     

ZnO纳米棒阵列/纳米颗粒团聚复合膜的制备及其光电性能

采用恒温水浴法在FTO导电玻璃上制备出了ZnO纳米棒阵列,然后对其进行二次生长后得到了ZnO纳米棒阵列/纳米颗粒团聚复合膜,最后它们分别与Pt形成对电极并与电解质溶液组装成染料敏化太阳能电池(DSSC)。结果表明:当在模拟太阳光照射(AM 1.5,100 mW/cm2)下时,ZnO纳米棒阵列/纳米颗粒团聚复合膜太阳能电池的短路电流密度Jsc为11.7 mA/cm2,开路电压Voc为0.661 V,填充因子FF为0.384,光电转换效率为3.17%,均明显的高于ZnO纳米棒阵列太阳能电池和ZnO纳米颗粒团聚球太阳能电池。其主要原因是由于ZnO纳米棒阵列/纳米颗粒团聚复合膜染料敏化太阳能电池在具有较高的光生电子传输效率的同时,增加了比表面积和提高了光子的收集效率。     

电解液温度对二氧化钛纳米管阵列结构及光电性能的影响

以氟化铵(NH4F)、乙二醇溶液为电解液,在不同的电解液温度(0～50℃)条件下,采用电化学阳极氧化法制备二氧化钛(TiO2)纳米管阵列.采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、紫外-可见分光光度计(UV-Vis)对TiO2纳米管阵列的形貌、结构和光学性能进行表征.结果表明,电解液温度高于20℃均能制备出纳米管阵列.光照下电解液温度40℃时制备的TiO2纳米管阵列具有最高光电流密度(Iph)0.2408 mA/cm2.以活性艳红X-3B为目标降解物,在室温、紫外光照射条件下考察了电解液温度对光催化活性的影响,结果显示电解液温度40℃时制备的TiO2纳米管阵列具有最高的光催化活性.     

CsI-LiCl共晶材料的坩埚下降法生长与闪烁性能研究

本文采用坩埚下降法,在真空密封的石英坩埚中成功生长出CsI-LiCl与CsI-LiCl:Na共晶闪烁体。通过扫描电子显微镜(SEM)观察晶体微结构表明该共晶中LiCl相与CsI相存在周期性的层状排列,CsI相的厚度在5 μm左右。共晶样品的X射线激发发射谱显示在CsI-LiCl和CsI-LiCl:Na共晶样品存在缺陷发光,在CsI-LiCl样品中还观察到了纯CsI的自陷激子(STE)发光。CsI-LiCl样品在α粒子激发下的多道能谱中观察到明显的全能峰,这一结果证明CsI-LiCl共晶可用于热中子探测的潜力。     

静电纺丝法制备CeO2微纳米纤维及其除氟性能

以聚丙烯腈(PAN)为载体,六水合硝酸铈[Ce(NO₃)₃·6H₂O]为原料,采用静电纺丝法制备了Ce(NO₃)₃/PAN纤维,在空气中热处理得到CeO₂微纳米纤维,通过XRD、BET和SEM对CeO₂微纳米纤维进行表征。采用静态吸附实验探讨了CeO₂微纳米纤维去除水溶液中氟离子的性能,考察了溶液pH值、初始氟离子浓度及共存阴离子等对吸附性能的影响。结果表明,pH=3时,CeO₂微纳米纤维对F^-的吸附性能最佳,CeO₂吸附量随着F^-浓度的增大呈上升趋势。CeO₂微纳米纤维对F^-的吸附等温线遵循Langmuir模型,二级动力学模型能很好地描述CeO₂微纳米纤维对F^-的吸附过程。CeO₂微纳米纤维的除氟性能优良,可为其实际应用提供理论参考。     

X-ray analysis of sideroxol from <Emphasis Type="Italic">Sideritis leptoclada</Emphasis>

Sideroxol (1), a kaurane diterpene which has the ent-7α,18-dihydroxy-15β,16β-epoxykaurane structure (MW = 320.47, C₂₀H₃₂O₃) was obtained from the acetone extract of Sideritis leptoclada plant as well as from some other Sideritis species. It crystallizes in the orthorhombic space group P2₁, 2₁, 2₁ with a = 10.967(3), b = 24.555(5), c = 6.372(4) Å, Dc = 1.240 g cm⁻³, Z = 4, and refines to R = 0.065 for 721 independent reflections. The skeleton consists of three fused six-membered rings and a five-membered ring with fused epoxide. The six membered rings exhibited slightly distorted chair conformation. In addition to sideroxol, two kaurane and five kaurene diterpenes were isolated from the hexane and acetone extracts of the studied plant.     

Photoluminescence characteristics of Mg- and Si-doped GaN thin films grown by MOCVD technique

We have studied the optical, structural and surface morphology of doped and undoped GaN thin films. The p- and n-type thin films have been successfully prepared by low-pressure MOCVD technique by doping with Mg and Si, respectively. The different carrier concentrations were obtained in the GaN thin films by varying dopant concentrations. Photoluminescence (PL) studies were carried to find the defect levels in the doped and undoped GaN thin films at low temperature. In the undoped GaN thin films, a low intensity and broad yellow band peak was observed. The donor–acceptor pair (DAP) emission and its phonon replicas were observed in both the Si or Mg lightly doped GaN thin films. The dominance of the blue and the yellow emissions increased in the PL spectra, as the carrier concentration was increased. The XRD and SEM analyses were employed to study the structural and surface morphology of the films, respectively. Both the doped and the undoped films exhibited hexagonal structure and polycrystalline nature. Mg-doped GaN thin films showed columnar structure whereas Si-doped films exhibited spherical shape grains.     

New zeotype borophosphates with chiral tetrahedral topology: (H)0.5M1.25(H2O)1.5[BP2O8]·H2O (M = Co(II) and Mn(II))

Two new isostructural open‐framework zeotype transition metal borophosphate compounds, (H)_0.5M_1.25(H₂O)_1.5[BP₂O₈]·H₂O (M = Co(II) and Mn(II)) were synthesized by mild hydrothermal method. The structure of compounds were characterized by single‐crystal X‐ray diffraction which have ordered, alternating, vertex‐sharing BO₄, PO₄, and (MO₄)OM(H₂O)₂ groups with hexagonal, P 6₁ 2 2 (No 178) space group and unit cell parameters for Co a = 9.4960(6) Å, c = 15.6230(13) Å, for Mn a = 9.6547(12) Å, c = 15.791(3) Å, Z = 1 for both of them. TGA/DTA analysis, IR spectroscopy were used for characterization. Magnetic susceptibility measurements for both of the compound indicate strong antiferromagnetic interaction between metal centers. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Solubility of Ag2O into the Na2O–B2O3–Al2O3 system

The solubility of Ag₂O was measured for the Na₂O–B₂O₃ and Na₂O–B₂O₃–Al₂O₃ system with the rotating crucible method and static method, respectively, under air atmosphere at temperatures ranging from 1273 to 1423 K. The contamination of melts from crucibles could be avoided by the rotating crucible method, with which it became possible to measure the solubility of Ag₂O for the Na₂O–B₂O₃ system above the melting point of Ag for the first time. It was found that the addition of Na₂O decreases the solubility of Ag₂O while the addition of Al₂O₃ had little effect on the solubility. The effect of Na₂O and Al₂O₃ on the solubility of Ag₂O is expressed by interaction coefficients and is analyzed in terms of the basicity of melts. The solubility of Ag₂O in Na₂O–B₂O₃–Al₂O₃ melts increased with increased temperature. This phenomena was explained by a small enthalpy change in oxidation of silver.     

Considerations on the structure and physical properties of B2O3-SiO2 and GeO2-SiO2 glasses

Data of density, refractive index and thermal expansion coefficient for B₂O₃-SiO₂ and GeO_2-SiO₂ glasses have been analyzed. The volumes of the structural units are the same found for the vitreous B₂O₃, GeO₂ and SiO₂. The volume of any structural unit is constant over the entire composition region of the glass system. The same has been found for the differential refraction and unit refraction of the structural units in these glasses. Different features are observed for the differential expansion of the structural units. There is a considerable change with composition in the differential expansion of BO₃, GeO₄ and SiO₄ units. The effect is attributed to a change in the asymmetry of vibrations with the number of Si-O-B or Si-O-Ge linkages in the matrix. The thermal expansion coefficient is mainly determined by the contribution of B₂O₃ or GeO₂ in the concerned glasses.     

Molecular structure and crystal packing of uncomplexed 1,6-bis(N-cyano-p-methoxy-anilino)-2,4-hexadiyne, C22H18N4O2

The X-ray crystal structure of 1,6-bis(N-cyano-p-methoxy-anilino)-2,4-hexadiyne, C₂₂H₁₈N₄O₂, is determined. The crystal packing is dominated by phenyl stacking interactions. Weak C–H···N hydrogen bonds help align the molecules. C–H··· hydrogen bonding is not apparent.     

Structural and electrical properties of vapour phase grown Cd1 − xFexTe single crystals

Cd_1 − xFe_xTe single crystals were prepared by vapour phase growth method in the composition range of 0 ≤ x ≤ 0.03. Chemical analysis, surface morphology, structural investigations and electrical properties were carried out by EDAX, SEM, XRD, TEM and transport technique, respectively. Microscopic variations between the target and actual compositions were noticed. Morphology studies revealed that dislocation aided growth is active in the present crystals. TEM and XRD studies confirmed that the samples of all compositions crystallized in zinc blende structure, and the lattice parameters varied almost linearly decreases with Fe content. At room temperature, the resistivity of the Cd_1 − xFe_xTe crystals of all compositions (x = 0.01, 0.015, 0.02, 0.025 and 0.03) lies in the range of 3.5-6.5 M Ω, the activation energies lie in the range of 63-133 meV, and the samples were show the ‘p’ type conductivity.     

空位浓度对纤锌矿CdS电子结构和光学性质影响的第一性原理研究

本文基于密度泛函理论的平面波超软赝势方法,采用第一性原理研究了含Cd空位缺陷CdS和含S空位缺陷纤锌矿CdS的几何结构、能带结构、电子态密度及光学性质。通过计算分析可知,含Cd空位缺陷的CdS体系均为p型半导体,含S空位缺陷的CdS体系跃迁方式均由直接跃迁变为间接跃迁。Cd、S空位缺陷的CdS体系的态密度总能量降低。空位CdS体系相较于本征CdS体系的静介电常数均有提高,并随着空位浓度的增大而增大,Cd空位缺陷体系更为明显,极化能力得到显著提升。空位Cd的CdS体系相较于本征CdS体系在红外波段存在明显的吸收,空位S的CdS体系相较于本征CdS体系在可见光波段存在明显的吸收。