Nonlinear Dynamics of Electrochemical Reaction Networks

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With this award, the Chemical Structure, Dynamics and Mechanisms (CSDM-A) Program of the Division of Chemistry is funding Professor Istvan Z. Kiss and his research group at Saint Louis University to study pattern formation of electrochemical reactions. For most chemical reactions that occur in gaseous or liquid conditions, the reacting atoms or molecules steadily decrease in number, and the product atoms or molecules steadily increase in number until the reaction is complete (or, we say when it reaches "equilibrium"). Prof. Kiss is interested in so-called oscillating chemical reactions, in which the number of molecules of certain substances fall and rise with time. In other words, the reaction sometimes proceeds in the forward direction, and at other times in the reverse! Oscillating reactions can produce solutions that switch from blue to yellow color and back to blue, or they can produce patterns of color that may resemble zebra stripes or leopard spots. Such pattern formation is an example of chemical reaction networks, which are not yet fully understood but are very relevant to how living systems evolve and function. Prof. Kiss' research adds another twist to oscillating reactions: rather than just mixing reactants together in a beaker, he generates reactants with electrodes immersed in the solution. For example, nickel electrodes can generate nickel ions (Ni(2+)) at a precisely controlled rate. This means that the oscillations and patterns created can be controlled, and in turn the chemical network behavior better understood. In addition to its relevance to biological systems, this research also has implications for battery and energy technologies. The graduate students and post-doctoral scientists involved in this project are immersed in a multidisciplinary experience that spans not only chemistry, but data science, mathematics, and biology.The overarching objective of this project is to discover the laws that govern self-organization and pattern formation in complex, far-from-equilibrium charge transfer chemical reactions. The project is following three tracks: 1) Spatially Organized Electrochemical Media on the Microscale. The emergent networks that form in lab-on-chip devices are decoded. The coupling topology among the microelectrodes is used to identify novel types of dynamical structures with simple equilibrium reactions, including metal dissolution systems (Ni(0)/Ni(2+), Cu(0)/Cu(2+)) and the H2 oxidation reaction. 2) Cathode-Anode Interactions: The nature and structure of cathode-anode interactions are determined with bipolar electrodes and serially coupled electrochemical cells. Models of network topology developed in this study are tested for their utility in describing the dynamics of battery cells. 3) Chimera Patterns on Designed Electrochemical Networks: Modular networks of current generating reactions are built with known network configurations. The resilience and the scalability of the localization of the synchronization patterns are explored by changing the number of elements in each module and the number of modules. In addition to the aforementioned formal training of students and post-doctoral researchers, demonstrations of nonlinear chemical dynamics are being incorporated into the undergraduate curriculum, as well as public outreach events.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.