Study on the microscopic processes of the emergence of electrochemical instability at soft interfaces

利用在玻璃毛细管顶端形成的小液-液界面，研究了界面面积对电化学不稳定性（EI）产生的影响。随着表面积的减小，引起不稳定性的浓度增大。这种表面面积对异常增加电流（AIIC）的影响提示有必要区分EI条件的满足和EI外观的形式。用毛细管电曲线和伏安法同时测定了十二烷基硫酸盐（DeSO_4^-）和十二烷基铵（DeNH_3^+）离子在1,2-二氯乙烷-水界面上的吸附特性。DeSO_4^-和DeNH_3^+的吸附吉布斯能均与界面电位降呈线性关系，其比例常数分别为9.1和9.8 kJ mol^<-1> V^<-1>。建立了EI出现的成像方法。我们用荧光探针、磷脂修饰了界面，观察了界面微观结构进入EI模式的荧光图像。在施加电位的稳定区域，界面转移没有引起均匀荧光图像的变化，但在界面处于EI模式的电位范围内，荧光图像呈现不均匀性，出现暗域。在EI条件下，暗域的大小在电位区有波动和振荡，而在AIIC条件下则没有

The effect of the area of the interface on the emergence of the electrochemical instability(EI)has been studied using the small liquid-liquid interface formed at the tip of a glass capillary. With the decrease in the surface area, the concentration to cause the instability increases. This effect of the surface area on the abnormally increased current (AIIC) suggests the necessity of differentiating the fulfillment of the condition for EI and the form of the appearance of the EI.The adsorption properties of decylsulfate (DeSO_4^-) and decylammonium (DeNH_3^+) ions at the 1,2-dichloroethane-water interface by measuring simultaneously an electrocapillary curve and a voltammogra. The adsorption Gibbs energies of DeSO_4^- and DeNH_3^+ are both linearly dependent on the potential drop across the interface, and their proportionality constants are 9.1 and-9.8 kJ mol^<-1> V^<-1>, respectively.The method of imaging the emergence of EI has been established. We modofiedtheinterfacewith a flurescent probe, a phosopholipid, and observed the fliorescence images of the microscopic structure of the interface entering the mode of EI. While the interfacial transferof does not cause any change in the uniform fluorescence image in the stable region of the applied potential, in the potential range where the interface is in the EI mode, the fluorescence image shows inhomogeneity and dark domains emerge. The size of the dark domain fluctuates and oscillates in the potential region under the EI condition but not under the AIIC conditions/