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

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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/