Accelerating fronts in an electrochemical system due to global coupling.
Accelerating fronts in an electrochemical system due to global coupling.
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DOI：
10.1103/physreve.51.3997
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发表时间：
1995-05
期刊：
影响因子：
--
通讯作者：
Flätgen;Krischer
中科院分区：
文献类型：
--
作者：
Flätgen;Krischer
我们研究了在电化学电池的银环电极上过二硫酸盐还原为硫酸盐的时空模式。在恒电位条件下，该反应在电流-电压特性中表现出双稳态行为。这两种稳定状态的特征是双层上的电压降不同。我们研究了双稳区域中不同态之间的跃迁。对电极-电解液界面电压降的时空分辨测量表明，该转变是通过前沿发生的。我们能够通过电场的局部微扰来触发这些前沿，从而研究它们对工作参数的依赖关系。结果表明，前锋的运动是由迁移电流(电场引起的离子运动)引起的，因此系统可用反应-迁移-扩散方程来描述。锋面的速度随着时间的推移而增加，因此它们被加速。这与通常的反应扩散系统的前沿解不同，后者在一维几何中具有恒定的速度。这种加速度被证明是通过电场调节的全局耦合的结果，或者更准确地说，是非局部耦合的结果。
We examine spatiotemporal patterns during the reduction of peroxodisulfate to sulfate at silver ring electrodes in an electrochemical cell. The reaction displays bistable behavior in the current-voltage characteristics under potentiostatic conditions. The two stable states are characterized by different voltage drops across the double layer. We investigate transitions in the bistable region between the different states. Spatiotemporally resolved measurements of the voltage drop across the electrode-electrolyte interface show that the transition occurs via fronts. We are able to trigger these fronts by local perturbations of the electric field and thus to examine their dependence on operating parameters. It is shown that the movement of the fronts results from migration currents (movement of ions due to the electric field), and hence the system is described by reaction-migration-diffusion equations. The velocity of the fronts increases with time; hence they are accelerated. This contrasts with usual front solutions of reaction-diffusion systems, which possess a constant velocity in one-dimensional geometries. This acceleration is shown to be a consequence of a global, or more precisely nonlocal, coupling mediated through the electric field.