Fronts, Waves, and Stationary Patterns in Electrochemical Systems

Abstract

Oscillatory behavior has been observed for almost all electrochemical reactions in a certain, although sometimes small, range of external parameters. Only in the past ten years has it been possible, however, to find a common explanation for the occurrence of these temporal self‐organization phenomena of chemically completely different electrochemical reactions. The breakthrough was achieved because new methods and concepts, which had been developed in nonlinear dynamics to describe the spontaneous formation of order in various disciplines, could be applied. This development in turn was only possible because the underlying laws are universal at a certain abstract level. Oscillations are only one possible manifestation of nonlinear behavior. Examples of other features that are often closely associated with temporal instabilities are spatial structures and waves. Initiated by the theoretical progress and the development of new experimental techniques, spatial pattern formation in electrochemical systems has been targeted for investigations in the past few years. Based on these investigations, it can be predicted under which conditions temporal or spatial pattern formation can be expected. Furthermore, the possibility of predicting the occurrence of instabilities indicates that it might be feasible to exploit nonlinear effects to increase, for example, the yield of electrocatalytic reactions. Here we discuss physicochemical mechanisms that lead to pattern formation in electrochemical systems. At the same time, we stress the generic principles that are responsible for self‐structuring processes in many chemical and biological systems.

Spatio-temporal organization in a morphochemical electrodeposition model: Hopf and Turing instabilities and their interplay

“…The notable circumstance that experimental patterns found in electrodeposition processes exhibit structures that are strongly reminiscent of those found in many different natural systems (such as fish and animal coat markings, sand dunes, grass landscapes) has suggested that such experimental electrochemical scenarios could be explained within the reaction-diffusion modelling framework [40,45].…”

“…The mathematical modelling of electrochemical dynamics and of the related pattern formation processes has been mainly developed for variants of the activator-inhibitor mechanism and focused on electrocatalysis [36,40,45] more than electrodeposition. Nevertheless, in this field experimental pattern formation has been observed in a series of experiments regarding, among others, Ag [27,38], Co-In [39] and Ni-P-W-Bi [15] alloys.…”

The electrochemistry of quinizarin revealed through its mediated reduction of oxygen

“…2 nm apart. At such large interatomic distance, interactions between the redox centers will be minimal, thus the rapidity of the phase change is likely caused by the presence of negative differential resistance leading to bistability within the electrochemical system (21).…”

Electrochemical Waves on Patterned Surfaces: Propagation through Narrow Gaps and Channels

“…[8][9][10] Electrochemistry is an ideal playground for the study of dynamic instabilities because here most experiments are carried out under conditions far from thermodynamic equilibrium. It is therefore not surprising that the majority of known bistable, oscillating, and chaotic reactions is found in electrochemistry.…”

“…The range and the strength of this spatial coupling are determined by parameters such as the cell geometry, the external resistance, and the conductivity of the electrolyte. 10 In many standard electrochemical applications, the setup creates strong, long-range coupling through the electrolyte, which hampers the formation of pronounced spatial patterns. For the case of weak, long-range coupling, however, complex spatiotemporal oscillations [11][12][13][14] as well as accelerating 15 and "remote-triggered" fronts 16 have been observed.…”