<b>Abstract: </b><br/>This work uncovers the effect of component diffusivities, local convection, and reaction kinetics on cyclic voltammetry (CV). A finite element-based software, COMSOL Multiphysics, is used for the simulation employing species transport equation, electrode reaction with Faraday's law, and Butler Volmer equation. All the calculations are done taking two dimensional (2D) Cartesian geometry with an assumption that gradients of all the variables with other orthogonal directions except electrode to bulk solution normal direction are negligible. A mono electronic system with the electrode reaction, Ox + e &lt;-- &gt; Red, is considered for all the simulations. Diffusion, to be more specific relative diffusion of components, plays a significant role in determining the nature of CVs, and the same is reported here in detail. The effect of local flow near the electrode surface is also considered as a parameter of variation, and the same revealed a family of unique characteristic CVs. The impact of associated bulk reactions on the CVs has also been explored in detail. Moreover, the impact of a competing chain reaction has also been covered and discussed in the current study. For the taken set of parameters in this work, it has been observed that convection happens faster (magnitude of time scale is less) and the same affects the oxidation and reduction peaks extensively. To be specific, in a competing reaction where the component 'Red' vanishes leads to mitigation or disappearance of reduction peak depending upon the strength of the chemical reaction. Further, it is observed that a bulk reaction mitigates both the oxidation and reduction peak currents. The study concludes that four different time scales, namely diffusion time scale, reaction time scale, scan time scale, and convection time scale, determine the ultimate fate of the CVs. A detailed parametric study changing diffusivities of components, the reaction rate constant, convection strength is done to classify into different segment zones of CV characteristic curves. Different three-dimensional (3D) plots have been framed to show the relative effects of various time scales on CVs. It has been observed that the nature of the CVs, including oxidation and reduction peak current and peak position, depends on all the discussed time scales and the extent of dependencies varies. This particular work will assist researchers, engineers, and scientists in understanding CV in a detailed manner.

Computational Investigation of the importance of diffusion, convection, and reaction time scales on electrochemical cyclic voltammetry characterizations

ACS Spring Meeting 2021

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