电化学的前沿与展望

电化学是物理化学的重要分支,主要研究电子导体-离子导体、离子导体-离子导体的界面现象、结构和化学过程,以及与此相关的现象和过程.电化学研究的内容包括两个方面:(1)电解质的研究,即电解质学(或离子学),包括电解质的导电性质、离子的传输特性、参与反应的离子的平衡性质等,其中电解质溶液的物理化学研究常称电解质溶液理论;(2)电     

界面振荡现象

表面活性剂十二烷基三甲基溴化铵从水相向硝基乙烷相的迁移导致以界面振荡为特征的界面不稳定现象，基于界面吸附平衡对该现象的成因进行解析，得到了体现溶质界面吸附和扩散迁移的双因素关系式，可对界面振荡运动的成因及有关规律作出解释。     

BBDMS-PPV/ITO界面结构ADXPS研究

聚合物电致发光器件（Polymer Electroluminescent Device,PLED)已显示出广阔的应用前景^[1-6]。已往人们比较重视阴极材料的选择及相关金属与有机界面的研究^[7],而有关发光层或空穴传输层与阳极ITO膜之间的界面结构及化学问题则少见报道。事实上,ITO膜与有机层之间的作用对器件的可靠性及寿命具有更为严重的影响^[8,9]。由于异质界面的过渡层结构复杂,以纳米尺度上化学组成是非计量比的,因此对这种极薄的埋藏界面的研究方法还需进一步探索。本文通过模型试样制备和变角X射线光电子谱（ADXPS）技术,对PLED中共轭导电聚合物聚2,5－二（二甲基正丁基硅基）对苯乙烯撑（BBDMS－PPV）与阳极ITO膜所形成的界面结构进行了初步研究。     

浅析SOFC性能衰减的材料因素

从SOFC工作状态出发,分析了材料在氧化还原气氛中的固-气界面化学稳定性、材料间固-固界面的扩散与相互反应的特性以及外部化学物质的介入对三相界面反应等方面因素对电池性能可能产生的影响.故我国应注重探究实用的SOFC电池性能衰减材料因素.     

电极/溶液界面内层形成熵的统计力学处理

根据文[1a]提出的电极/溶液界面偶极取向分布模型, 导出金属/溶液界面内层形成熵ΔS~(m-d)(σ)以及溶剂化层构型熵S_k(σ)的统计力学计算式, 讨论了影响ΔS~(m-d)变化的主要因素, 并给出对汞/甲醇、汞/碳酸亚乙酯和汞/水溶液等三种界面的处理结果.     

X型与线型嵌段聚醚在空气/水和正庚烷/水界面上聚集行为的比较研究

通过阴离子聚合方法合成了环氧乙烷(EO)含量和分子量均相同的线型聚氧丙烯(PEO)-聚氧乙烯(PPO)(LPE)和X型聚氧丙烯-聚氧乙烯(TPE)嵌段聚醚,考察了它们在空气/水及正庚烷/水界面上聚集行为的差异.界面活性的研究结果表明,TPE降低水、正庚烷界面张力的效率和效能均低于LPE的.聚醚分子在正庚烷/水界面达到吸附平衡的时间比在空气/水表面短.由于正庚烷分子插入到聚醚吸附层中,聚醚分子可以在正庚烷/水界面上采取更为直立的状态,因此聚醚分子在正庚烷/水界面扩散较快.聚醚在正庚烷/水界面的扩张弹性高于空气/水表面的.     

纳米SiO_2在注水-驱油-油水分离中的界面调控研究进展

表面与界面行为在石油注水开发中广泛存在.功能性纳米二氧化硅具有在油-水-岩石三相界面吸附/聚集/解吸附的独特效应,有望在经济、高效和绿色环保的石油开发技术中得到应用.本文针对注水、注化学剂驱油及采出液的油水分离三个应用方向,以改变注入液-原油-岩石三相之间的界面作用为切入点,介绍了纳米二氧化硅的表面功能化及其在调控油/水/岩石三相界面中的研究进展,总结了其界面调控作用机制.最后,结合课题组研究工作,指出了功能性纳米二氧化硅表面结构调控与应用的研究方向.     

固态锂电池界面优化策略的研究进展

固态锂电池具有安全性好、能量密度高等优点,在新能源汽车和智能电子等领域具有广泛的应用前景。然而,由化学/电化学和物理因素引起的界面副反应与高界面阻抗问题制约了其进一步发展。先前的综述已对解决化学/电化学界面问题的方法有了相对全面的阐述,但并未细致讨论不同结构固态电池中物理界面的影响及应对策略。本文将简要介绍化学/电化学界面问题及其解决方案;重点按结构特点将固态锂电池分为三明治结构、粉末复合结构和3D一体化结构,细致地分析不同电池结构的物理界面特点与优化策略,并对各种策略的优缺点进行比较分析;最后,对固态锂电池电极/电解质界面的未来研究方向进行展望。     

石油磺酸盐结构与界面活性关系研究

对25个不同来源及批次的石油磺酸盐样品进行界面张力测试、质谱分析,研究了其结构与界面活性之间的相互关系.实验结果表明:高碳链C17~C25磺酸盐含量的高低对界面活性具有最主要的影响,含量较高则界面活性较优.另外当样品所含组分的分子量在200~800范围内均匀分布时,相对丰度最大的分子离子峰聚集在479(C23苯磺酸盐)附近的样品界面活性则较优.     

界面不稳定现象与相间迁移

包含有流动界面的多相体系中的溶质相间迁移在一定条件下可导致表现为界面变形、界面流和多种形式界面运动的不稳定现象．该现象的直接驱动力是界面局部区域出现的张力梯度，表面活性物质在该现象中起重要作用[1，2]．溶质相间迁移通常可考虑为三步：（1）溶质在原所在相内部向     

Solutal Marangoni effect : I. Pure interfacial transfer

The motion of a nitroethane lens located at the surface of an aqueous solution of dodecyltrimethylammonium bromide is analyzed. This motion is generated by a solutal Marangoni effect, or soluto—capillary instability, induced by the transfer of the surfactant from one phase to the second one, both solvents being mutually saturated; its quasi-periodic character is demonstrated by a statistical and spectral analysis, and its characteristics, amplitude, and frequency are discussed as a function of the physicochemical conditions. The enhancement of the interfacial transfer by the Marangoni effect is evaluated. It is shown that none of the available models of linear stability analysis can account for the present results.     

异丁醇-水-硝基乙烷体系中的双因素自耦合界面不稳定现象

指导了发生在异丁醇、硝基乙烷和水三组分两相体系中的多因素复合界面不稳定现象，文中通过对一个滴加在异丁醇水溶液表面的硝基乙烷液滴的运动特征的分析，揭示了该现象的规律，在体系趋于热力学平衡的过程中，硝基乙烷液滴先表现出周期性的振荡运动，然后转变为螺旋线和圆周运动，提出了一个溶质迁移和相间溶解的双因素自耦合机理，认为该现象的根本起因是表面活性剂溶质相间迁移所导致的溶质Ｍａｒａｎｇｎｉ效应，但由于丁醇的相     

Middle-phase microemulsions of green surfactant alkyl polyglucosides

Microemulsions are important organized molecular assembles in surfactant solutions and are used in various fields such as tertiary oil recovery, pharmaceutics, cosmetics, nanoparticle synthe-sis and chemical engineering. The more commonly used nonionic surfactants to produce micro- emulsions are the ethylene oxide-based compounds (CiEj). In recent years alkyl polyglucosides have been received considerable attention in producing microemulsions[17]. Alkyl polyglucosides (APG), which are widely…     

Electrochemical instability in the transfer of cationic surfactant across the 1,2-dichloroethane/water interface

The electrochemical instability has been shown to appear in the transfer of cationic surfactant ions across the 1,2-dichloroethane/water interface. Cyclic voltammograms possess all fundamental characteristics that are predicted by the theory of electrochemical instability: the presence of the instability window, that is, the potential range where the interface becomes unstable, the location of the instability window around the standard ion transfer potential of surface-active ions, and the dependence of the width of the instability window on the concentration of the surfactant ions. Electrocapillary measurements clearly demonstrate that the interface becomes unstable, while the interfacial tension is positive, being higher than 20 mN m(-1). The electrocapillary curve exhibits the discontinuities at both ends of the instability window, indicating the similarity between the electrochemical instability and the phase transitions induced by the temperature, pressure, and chemical potential. The results from voltammetry and interfacial tension measurements for cationic surfactants support the idea that the electrochemical instability, so far reported in the transfer of anionic surfactants across the liquid/liquid interface, is one of intrinsic properties of the two-phase systems where the partition of surface-active ions takes place.     

Scanning electrochemical microscopy (SECM) studies of oxygen transfer across phospholipid monolayers under surface pressure control: comparison of monolayers at air/water and oil/water interfaces

Scanning electrochemical microscopy has been used in combination with a specially designed Langmuir trough to compare the kinetics of oxygen transfer across an L-alpha-phosphatidylethanolamine, distearoyl monolayer spread at three different interfaces: air/water, air/water in contact with an oil lens, and oil/water. The monolayer is shown to reduce the kinetics of interfacial transport, and rate constants for the transport of oxygen across each interface, at different surface pressures, have been evaluated. The results obtained for each interface are compared, and the implications for studies of passive diffusion across cell membranes are discussed.     

Water-in-crude oil emulsions from the Norwegian continental shelf

A destabilization study of water-in-crude oil emulsions based on crude oils from the Norwegian Continental Shelf is reported. It is found that medium-chain alcohols (1-butanol and benzyl alcohol) and amines are speeding up the separation of water. The destabilization mechanisms in these two cases seem to be fundamentally different. The alcohols seem to modify the rigidity of the interfacial film by a diffusion/partitioning process while the amines show a strong and specific interaction with interfacial groups, hence hydrophilizing the whole film. Observed trends in the time-dependence of the interfacial tension upon addition of alcohols and amines support these suggestions to destabilization mechanisms. Data for a commercial demulsifier Dissolvan 4455 are also given.     

Spontaneous periodic pulsation of contact line in oil/water system--frequency control with divalent cations and applied voltage

Periodic oscillatory change of hydrophilicity (or hydrophobicity) of a glass surface was studied. A glass capillary was immersed normally at an oil/water interface. The water phase contained the cationic surfactant trimethyloctadecylammoniumchloride, and the oil phase contained bis(2ethylhexyl) phosphate. Adsorption of the surfactant molecules and their desorption via anionic chemicals dissolved in the oil generated a gradual wetting by the water, followed by a rapid wetting by oil. The three phase contact line exhibited a pulse-like motion that continued, at least for a few minutes. The frequency depended on the cation species dissolved in water and the applied voltage across the oil/water interface. Four kinds of cations, Mg(2+), Ca(2+), Sr(2+) and Ba(2+) were used. While the frequency order was Ba(2+)>Sr(2+)>Mg(2+), the Ca(2+)-containing interface did not show any motion irrespective of the applied voltage. There was a threshold voltage and concentration of anionic chemical that was necessary for the onset of this motion. The pulsation mechanism and its ion selectivity are also discussed. This interfacial motion was a typical nonlinear oscillation with an ion-selective nature. In this regard, this interfacial motion had biomimetic characteristics.     

Electrochemical Behavior of Anthraquinone in Reverse Micelles and Microemulsions of Cetyltrimethylammonium Bromide

The electrochemical behavior of an anthraquinone (AQ) was studied in aqueous solutions at a glassy carbon electrode, using the sodium salt of anthraquinone-2-sulfonic acid (AQS), by employing cyclic voltammetry. AQ undergoes a two-electron reduction in aqueous media. The electrochemical behavior of AQ was also investigated in micelles, reverse micelles (CTAB/1-butanol/water), and microemulsions (CTAB/1-butanol/water/cyclohexane) of cetyltrimethylammonium bromide (CTAB). The electrode reactions of AQ in reverse micelles and microemulsions are nearly reversible at low oil (cyclohexane) content. However, at higher oil content, the reversibility is gradually lost. In the case of reverse micelles, the reduction current, as well as the reduction potential, of AQ depend on the transition from a micellar solution to a stable solution of reverse micelles that occurs with added 1-butanol. In microemulsions, the change in cyclohexane content was found to cause a linear increase in the peak current for AQ reduction as well as a linear decrease in the corresponding reduction potential. As the cyclohexane content is increased, the o/w microemulsions dominated by micelles undergo a transition to a w/o microemulsion dominated by reverse micelles, which causes changes in the electrochemical behavior.     

Channel shape effects on the solution-flow characteristics and the liquid/liquid extraction efficiency in polymer microchannel chips.

A polymer microchannel chip with a symmetrical or unsymmetrical zigzag-side-walled structure was fabricated by an imprinting method, and applied to study shape effects on solution flow characteristics as well as on the liquid/liquid extraction efficiency of an aluminium(III) chelate complex (Al-DHAB: DHAB = o,o'-dihydroxyazobenzene) in a microchannel chip. In an unsymmetrical zigzag-side-walled channel chip (us-channel), an oil/water interface was sinusoidal, while that in a symmetrical zigzag-side-walled channel chip (s-channel) was flat as long as the observation was made under an optical microscope. It was demonstrated that the efficiency of the water-to-oil (1-butanol) extraction of Al-DHAB in the microchannel was governed by the contact time between the two phases. As the most important results, furthermore, the extraction efficiency was higher in the us-channel, as compared with that in the s-channel, owing to the sinusoidal liquid/liquid interfacial structure and, therefore, to the high interfacial area between the two phases.