Dissipative solitons and backfiring in the electrooxidation of CO on Pt.

Philipp R. Bauer,Antoine Bonnefont,Katharina Krischer

doi:10.1038/srep16312

Abstract

Collisions of excitation pulses in dissipative systems lead usually to their annihilation. In this paper, we report electrochemical experiments exhibiting more complex pulse interaction with collision survival and pulse splitting, phenomena that have rarely been observed experimentally and are only poorly understood theoretically. Using spatially resolved in-situ Fourier transform infrared spectroscopy (FTIR) in the attenuated total reflection configuration, we monitored reaction pulses during the electrochemical oxidation of CO on Pt thin film electrodes in a flow cell. The system forms quasi-1d pulses that align parallel to the flow and propagate perpendicular to it. The pulses split once in a while, generating a second solitary wave in the backward moving direction. Upon collision, the waves penetrate each other in a soliton-like manner. These unusual pulse dynamics could be reproduced with a 3-component reaction-diffusion-migration model with two inhibitor species, one of them exhibiting a long-range spatial coupling. The simulations shed light on existence criteria of such dissipative solitons.

Highlights

Backfiring, the merging of two pulses or the formation of a bound pulse state[12,13,14,15,16,17,18]
We report the occurrence of soliton-like pulses and backfiring during the electrochemical oxidation of CO on a Pt thin film electrode in a flow cell
We have demonstrated that the survival of a collision of excitation pulses occurs in a purely self-organized manner in an electrochemical experiment, without the existence of either inhomogeneities in space nor with man-made changes of a parameter in time

Summary

Introduction

Backfiring, the merging of two pulses or the formation of a bound pulse state[12,13,14,15,16,17,18]. There are still many theoretical questions, and experimental examples of complex pulse interactions remain rare. We report the occurrence of soliton-like pulses and backfiring during the electrochemical oxidation of CO on a Pt thin film electrode in a flow cell. The dynamics is reproduced with a 3-component reaction-diffusion-migration system, elucidating the role of the long-range migration coupling for the unusual pulse interaction. At the same time it is of significant applied interest, especially in the context of electrode poisoning by adsorbed CO molecules in low temperature fuel cells. In this respect, its dynamical behavior in flow cells with active transport of reactants is of particular interest. For first investigations in this direction see[21,22,23]

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Conclusion