2,6-二乙酰吡啶类双希夫碱配合物的合成和研究 Ⅱ.Cu(Ⅱ)配合物的合成和研究

合成了五个2,6-二乙酰吡啶缩肼基硫代甲酸酯双希夫碱合铜(Ⅱ)配合物,用元素分析、磁化率、红外光谱及紫外-可见光谱等对它们进行了表征,研究了配合物的电化学性质和Cu₃L₂²X₂(X=Cl^-、SCN^-)的光电子能谱。结果表明:五个Cu(Ⅱ)配合物均为三核配合物,在Cu₃L₂²(SCN)₂中存在Cu(Ⅱ)间的自旋-交换作用。     

Carbon Black-Supported Single-Atom Co?N?C as an Efficient Oxygen Reduction Electrocatalyst for H2O2 Production in Acidic Media and Microbial Fuel Cell in Neutral Media

Single metal atom isolated in nitrogen-doped carbon materials (M N C) are effective electrocatalysts for oxygen reduction reaction (ORR), which produces H₂O₂ or H₂O via 2-electron or 4-electron process. However, most of M N C catalysts can only present high selectivity for one product, and the selectivity is usually regulated by complicated structure design. Herein, a carbon black-supported Co N C catalyst (CB@Co N C) is synthesized. Tunable 2-electron/4-electron behavior is realized on CB@Co-N-C by utilizing its H₂O₂ yield dependence on electrolyte pH and catalyst loading. In acidic media with low catalyst loading, CB@Co N C presents excellent mass activity and high selectivity for H₂O₂ production. In flow cell with gas diffusion electrode, a H₂O₂ production rate of 5.04 mol h⁻¹ g⁻¹ is achieved by CB@Co N C on electrolyte circulation mode, and a long-term H₂O₂ production of 200 h is demonstrated on electrolyte non-circulation mode. Meanwhile, CB@Co N C exhibits a dominant 4-electron ORR pathway with high activity and durability in pH neutral media with high catalyst loading. The microbial fuel cell using CB@Co N C as the cathode catalyst shows a peak power density close to that of benchmark Pt/C catalyst.     

基于压电力显微镜的铌酸锂电畴稳定性研究

研究了Z切700 nm厚的单晶铌酸锂(LiNbO₃)薄膜电畴的调控方法。利用X射线衍射仪(XRD)和原子力显微镜(AFM)对单晶LiNbO₃薄膜的晶向和形貌进行了表征,并通过外加电场对单晶LiNbO₃薄膜电畴进行调控。研究结果表明,该LiNbO₃薄膜具有单一的(006)衍射峰,表面光滑、粗糙度低(均方根粗糙度小于1 nm)。通过外加电场和预设电畴图案对LiNbO₃电畴进行精准调控,并测试了电畴稳定性。测试结果显示,调控后的电畴在温度为25~150℃内处于稳定状态,且在30 d内保持稳定,未发生弛豫现象。该研究为LiNbO₃电畴工程器件的研发和应用提供了重要的技术支撑。     

Divisors on Generic Complete Intersections in Projective Space

Let be a generic complete intersection of hypersurfaces of degree in -dimensional projective space. We study the question when a divisor on is nonrational or of general type, and give an alternative proof of a result of Ein. We also give some improvement of Ein's result in the case .

     

Adsorption enthalpy and desorption enthalpy during displacement of adsorbate to solvent in a liquid-solid system

The adsorption heat of the stoichiometric displacement process for the adsorption of a solute in a liquid-solid system was investigated. On the basis of the SDM-A and the rule of the additivity of energy, an expression which describes the dependence of the adsorption enthalpy on the nature and concentration of the solute, and on the solvent and adsorbent, was derived. The adsorption heat determined for the solute with the traditional method can be divided into two independent fractions, relating to the adsorption of the solute and to the desorption of the solvent. Experimental data on both isotherms from the literatures and precise calorimetry were used to test the adsorption heat and its fractions computed quantitatively via the equations presented in this study, and a satisfactory degree of conformity between them was obtained. Supported by the Natural Science Foundation of Shaanxi Province in China.     

铽与苯乙酮酸、2,2''''-联吡啶、1,10-菲口罗啉、三苯基氧膦铽三元配合物的合成、结构表征及荧光性能的研究

以硝酸铽、苯乙酮酸（HL）, 2, 2＇-联吡啶（dipy）、 1, 10-菲啰啉（phen）和三苯基氧膦（TPPO）合成了TbL3dipy（H2O）2, TbL3phen（H2O）2和TbL2（TPPO）2NO3 3种新型固态配合物. 用元素分析、电导率、红外光谱和核磁共振谱对其进行了表征, 确定了配合物的组成. IR表明, 配合物中羧酸根可能以单齿方式配位. 1HNMR显示, 苯乙酮酸根配位后苯环上5个氢原子的化学位移移向高场. 室温下测定了配合物的荧光激发光谱, TbL3dipy（H2O）2, TbL3phen（H2O）2和TbL2（TPPO）2NO3最佳激发波长分别为361.0, 359.0和367.0 nm;分别以最佳激发波长测定了配合物的发射光谱, 配合物TbL3dipy（H2O）2, TbL3phen（H2O）2 和TbL2（TPPO）2NO3显示Tb3＋离子的特征发射光谱, TbL3dipy（H2O）2和TbL3phen（H2O）2均产生四条谱带, 分别归属于^5D4-^7Fj（j= 6, 5,4,3）能级跃迁（TbL3dipy（H2O）2： 489.0, 545.0, 584.0, 620.0 nm;TbL3phen（H2O）2： 490.0, 544.0, 583.0, 620.0 nm）;但在相同测定条件下, TbL2（TPPO）2NO3仅显示5D4-7F5（544.0 nm）能级跃迁光谱. 3种配合物中TbL3dipy（H2O）2发光强度最高.