Email the author Influence of kinetic parameters and diffusion coefficients on stationary concentration of electroactive and electroinactive species in a model electrochemical process with a preceding chemical reaction
Abstract
This work is aimed at studying the influence of kinetic parameters and diffusion coefficients on stationary concentration distribution of electroactive and electroinactive species in a model electrochemical process with a preceding chemical reaction under constant current. We consider a preceding homogeneous first-order chemical reaction with a reversible heterogeneous electrochemical reaction at a planar electrode surface. To elucidate the peculiarities of stationary concentration distribution of electroactive and electroinactive species in a thin stagnant layer attached to a planar electrode surface, the exact solutions of a system of differential equations describing the variations of the concentrations of the participating species with a distance to electrode surface have been analyzed. The cases of equal and unequal diffusion coefficients of species involved in a preceding chemical reaction have been considered. It has been shown that the diffusion coefficients of both reacting species can affect their concentration profiles in a thin stagnant layer attached to electrode surface. The calculations demonstrate that the stationary concentration of electroactive and electroinactive species decreases with an increase of the diffusion coefficients. The influence of the rate constants of a preceding chemical reaction on the stationary concentration is different for electroactive species and electroinactive one. As the rate constants of a preceding chemical reaction are increased, the stationary concentration of electroactive species decreases, whereas the stationary concentration of electroinactive species increases slightly. This is also valid for the case of the stationary surface concentration of electroactive and electroinactive species. The thickness of a thin stagnant layer attached to a planar electrode surface where a change of the concentration of electroactive species takes place, also affects the stationary concentration distributions. The effect of this parameter is especially crucial at low values of a preceding chemical reaction rate constants.
Keywords
References
Laborda E., González J., Molina A. A reasoned general explanation about the concepts of diffusion and reaction layers. J. Solid State Electrochem. 2023. 28: 1259.
Baltes N., Thouin L., Amatore C., Heinze J. Imaging concentration profiles of redox-active species with nanometric amperometric probes: effect of natural convection on transport at microdisk electrodes. Angew. Chem. Int. Ed. 2004. 43(11): 1431.
León T., López J., Torres R., Grau J., Jofre L., Cortina J.-L. Time-dependent 2-D model for transport of species analysis in electrodialysis: Concentration profiles and fluxes. Desalination. 2023. 565: 116819.
Kovář P., Smoleň M., Pagáč J., Kincl M., Slouka Z. Experimental 3D concentration profiles along an electrodialysis channel reveal a strong effect of natural convection. Desalination. 2023. 548: 116302.
Gong L., Khodaparastasgarabad N., Hall M.D., Greener J. A new angle to control concentration profiles at electroactive biofilm interfaces: Investigating a microfluidic perpendicular flow approach. Electrochim. Acta. 2022. 431: 141071.
Kumar A., Craig V.S.J., Page A.J., Webber G.B., Wanless E.J., Andersson G. Ion specificity in the measured concentration depth profile of ions at the Vapor-Glycerol interface. J. Colloid Interface Sci. 2022. 626: 687.
Adnan F.H., Pons M.-N., Mousset E. Mass transport evolution in microfluidic thin film electrochemical reactors: New correlations from millimetric to submillimetric interelectrode distances. 2021. 130: 107097.
Krishnakumara S., Rani R.U., Narayanana K.L., Rajendran L. Theoretical analysis of the enzyme reaction processes within the multiscale porous biocatalytic electrodes: Akbari–Ganji’s and Taylor’s series method. Int. J. Electrochem. Sci. 2024. 19: 100527.
Mary L.C., Rani R.U., Meena A., Rajendran L. Nonlinear Mass Transfer at the electrodes with reversible homogeneous reactions:Taylor's series and hyperbolic function method. Int. J. Electrochem. Sci. 2021. 16: 151037.
Devi M.C., Pirabaharan P., Abukhaled M., Rajendran L. Analysis of the steady-state behavior of pseudo-first-order EC-catalytic mechanism at a rotating disk electrode. Electrochim. Acta. 2020. 345: 136175.
Baronas R. Nonlinear effects of diffusion limitations on the response and sensitivity of amperometric biosensors. Electrochim. Acta. 2017. 240: 399.
Zhao M., Qian Z.H., Qin R.J., Yu J.Y., Wang Y.J., Niu L. In situ SECM study on concentration profiles of electroactive species from corrosion of stainless steel. Corrosion Engineering, Science and Technology. 2013. 48(4): 270.
Pototskaya V.V., Gichan O.I. The Gerischer finite length impedance: a case of unequal diffusion coefficients. J. Electroanal. Chem. 2019. 852: 113511.
Gichan O.I. Peculiarities of the concentration distribution in the near-electrode layer in a course of homogeneous chemical reaction of the first order in a model electrochemical process under steady-state conditions. Him. Fiz. Technol. Poverhni. 2018. 9(3): 251.
Wolfram S. MathematicaTM. (Redwood City: Addison Wesley, 1988).
Copyright (©) 2024 O. I. Gichan
This work is licensed under a Creative Commons Attribution 4.0 International License.