热处理碳纸电极上VO2+/VO+2氧化还原动力学

在不同温度下热氧化处理碳纸, 用循环伏安、极化曲线和交流阻抗方法研究碳纸电极上VO2+/VO+2氧化还原动力学. 循环伏安和极化曲线结果表明, 随着热处理温度的升高, VO2+/VO+2氧化还原反应的速率常数及交换电流增大. 建立了VO2+/VO+2氧化还原反应的交流阻抗等效电路模型. 拟合结果表明, 热处理增大了碳纸电极表面的双电层电容, 减小了VO2+/VO+2氧化还原反应的电荷转移电阻. 用循环伏安和交流阻抗两种方法求得的VO2+和VO+2的扩散系数基本相同, 表明所构建的交流阻抗等效电路模型与电极反应过程相符合.     

DFT方法研究间苯二酚-甲醛气凝胶单体分子性质与振动频率

用B3LYP密度泛函方法在6-311G**基组水平上计算了单元、二元羟甲基间苯二酚的分子体积和振动频率,通过理论计算与实验结果的比较,探讨了间苯二酚-甲醛气凝胶形成的微观机理,具体分析了各振动模式的归属和同位素取代对振动频率的影响.     

动物组织中氨苯砜及其代谢产物残留量的液相色谱串联质谱法测定

建立了动物组织中氨苯砜及其代谢产物N-乙酰氨苯砜的液相色谱-电喷雾串联质谱检测方法(HPLC-ESI MS/MS).采用YMC-Pack Pro C18(3 μm,100 mm×2.0 mm i.d.)反相色谱柱,以碱性乙腈为提取液,以HLB和MCX固相萃取柱为净化柱,乙腈-水为流动相,梯度洗脱,流速0.3 mL/min,以正离子多反应监测模式测定,同位素内标法定量,进样量15 μL.方法的定量下限为0.5 μg/kg,线性范围为0.5 ～5.0 μg/kg,加标回收率为92% ～103%,相对标准偏差为4.8% ～11.0%.该法具有灵敏、准确等优点,适用于动物组织中氨苯砜及其代谢产物N-乙酰氨苯砜残留的确证检测.     

Effect of Sorbents Added on Adsorption Capability of Soil for Nano-TiO2

The adsorption capability of loam soil for nano-TiO2 affected by the amount and intensity of leached water has been investigated by simulating the natural rainfall process under the leaching condition.The results show that the amount and the intensity of leached water are two important factors affecting the adsorption capability of loam soil for nano-TiO2.The results indicate that the depth of the loam soil containing a maximal amount of nano-TiO2 is proportional to the amount of leached water,while it is i...     

半线性热方程的反馈零能控性

考虑具有Lipschitz非线性项,半线性热方程的最优控制问题.我们将运用观测不等式,证明值函数ψ作为相应Hamilton-Jacobi方程的唯一粘性正解是局部Lipschitz连续的.最后,运用动态规划方法,得到系统最优的反馈控制.     

非负矩阵谱半径的新界值

讨论n×n阶非负矩阵的谱半径估计,给出估计其界值的新方法,该方法易于计算且能得到比"非负不可约矩阵谱半径的估计"一文中精确度更高的界,并用数值例子验证了这种方法的有效性.     

Yb3+-Ho3+-F-共掺杂TiO2纳米晶的上转换发光性能及其在染料敏化太阳能电池中的应用

采用溶胶-水热法制备了Yb3-Ho3+-F-共掺杂的TiO2(简写为UC-F-TiO2)纳米粉末.通过XRD,TEM,拉曼光谱,XPS和发光光谱,研究了yb3掺杂浓度对UC-F-TiO2纳米粉末的结构、形貌和上转换发光性能的影响规律.结果表明:UC-F-TiO2纳米粉末颗粒的大小约20 nm,由金红石和锐钛矿两种结构混合组成,且随着yb3+掺杂浓度的增加,金红石结构的TiO2所占比例增加;在980 nm激光激发下,UC-F-TiO2发射出中心在543 nm、647 nm和751 nm处的三个发光带.研究了基于UC-F-TiO2和纯TiO2纳米多孔薄膜光阳极的染料敏化电池的光伏性能.结果表明:与纯TiO2制备的电池相比,将UC-F-TiO2应用于染料敏化电池,电池的光电转换效率提高了29.7;.     

3-取代-3-苯基-1-茚酮类化合物的合成

以3-苯基-1-茚酮（1）为原料,THF为溶剂,二异丙基氨基锂（LDA）为碱,与碘代烷（RI）经亲核取代反应合成了4个3-取代-3-苯基-1-茚酮类化合物（3a~3d),其中3b~3d为新化合物,其结构经¹H NMR, ¹³C NMR 和EI-GC-MS表征。在最佳反应条件［1 1.0 eq., LDA/RI=2.1/1.5（当量比）,于0 ℃~rt反应5 h］下,3a~3d收率为70％～80％。     

Adsorption of CO2 and H2 on Nitrogen-doped Porous Carbon from Ionic Liquid Precursor

Nitrogen-doped mesoporous carbon material was prepared via a simple one-step thermolysis method via the carbonization of ionic liquid, 1-cyanomethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([MCNIm]⁺[Nf₂T]^-). The nanostructure of the resultant carbon material was characterized by X-ray diffraction(XRD) and transmission electron microscopy(TEM) and the types of N-containing groups of the carbon material were investigated by X-ray photoelectron spectroscopy(XPS). The N-content of the carbon material is 18.6%(mass fraction) based on the elemental analysis. The produced mesoporous carbon material was further used as the solid sorbent for H₂ and CO₂. The hydrogen uptake capacity and H₂ isosteric heat of the carbon material were discussed. Furthermore, the nitrogen-containing carbon material as good sorbent shows relatively high adsorption and separation ability for CO₂ from CH₄, for which the heat of CO₂ adsorption(Q_st) is 31.8 kJ/mol. The mesoporous structure and nitrogen functionality make the carbon material with high adsorption capacity and selectivity for CO₂ and ability to store H₂, indicating that this kind of nitrogen-doped carbon material originated from ionic liquids is a promising sorbent material for high-performance separation and adsorption.     

纳米SnO2的水热法合成及光催化性能研究

以SnCl2·2H2O为原料、酒石酸为络合剂,采用水热法制备了SnO2纳米颗粒,通过X射线衍射(XRD)、扫描电镜(SEM),紫外-可见(UV-Vis)光谱及荧光光谱(PL)等对样品的物相结构、微观形貌、光吸收性能等进行分析表征,以酸性红B模拟染料废水,考察了其光催化性能.结果表明:不同水热温度下所合成的样品均为四方晶系SnO2,空间群为P42/mnm,晶胞参数a=b=0.4738nm,c=0.3187 nm;160℃下所得样品具有优异的光催化性能,颗粒基本呈球形,尺寸约为13～23 nm.当催化剂用量为20 mg/50 mL,紫外光为光源,反应时间为50 min时,酸性红B的降解率可达97.1;,且降解反应属于一级反应动力学机理.