Coupling covariance matrix adaptation with continuum modeling for determination of kinetic parameters associated with electrochemical CO₂ reduction

Creators: Corpus, Kaitlin Rae M.; Bui, Justin C.; Limaye, Aditya M.; Pant, Lalit M.; Manthiram, Karthish¹; Weber, Adam Z.; Bell, Alexis T.

1. California Institute of Technology

Abstract

In electrocatalysis, the rate of a reaction as a function of applied potential is governed by the Tafel equation, which depends on two parameters: the Tafel slope and the exchange current density (i₀). However, current methods to determine these parameters involve subjective removal of data due to the convoluted effects of mass transfer and competitive surface or bulk reactions, resulting in unquantifiable uncertainty. To overcome this challenge, we couple covariance matrix adaptation with a continuum model of CO₂ reduction (CO₂R) that explicitly deconvolutes non-kinetic effects to extract kinetic parameters associated with 26 literature datasets of CO₂R over Ag and Sn catalysts. The fitted kinetic parameters do not converge to a unique set of values, and the Tafel slope and i₀ possess an apparent correlation, which we suggest is a consequence of variations in catalyst preparation methods. This work facilitates rigorous benchmarking of electrocatalysts in systems where mass transfer is relevant.

Copyright and License

Acknowledgement

This material is based on work performed within the Liquid Sunlight Alliance, which is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Fuels from Sunlight Hub under award number DE-SC0021266. J.C.B. would like to acknowledge support from the National Defense Science and Engineering Graduate Fellowship (NDSEG) supported by the Army Research Office (ARO) under contract FA9550-21-F-0003. The authors would also like to acknowledge helpful discussions with Joy Zeng that helped guide the direction of the study.

Contributions

J.C.B. developed the model physics and COMSOL continuum model of CO₂R on Ag and Sn used in the study. K.R.M.C. and A.M.L. developed the utilized covariance matrix adaptation MATLAB code applied to fit kinetic parameters. K.R.M.C. linked the COMSOL and MATLAB codes to fit kinetic and transport parameters in the continuum model. J.C.B. and L.M.P. developed the sensitivity analysis for the CO₂R model. K.M., A.Z.W., and A.T.B. provided guidance and direction for the project. K.R.M.C. and J.C.B. prepared the original draft of the manuscript. All authors engaged in reviewing and editing the manuscript.

Data Availability

All COMSOL and MATLAB code for the coupled continuum modeling and CMA-ES method employed in this study are available on Zenodo: https://doi.org/10.5281/zenodo.7903605. All code is available for use through the MIT License (https://opensource.org/license/mit/). The digitized polarization and partial current density data for all Ag and Sn electrocatalysts fit in this study are openly available at Zenodo: https://doi.org/10.5281/zenodo.7866274.

Additional Information

One or more of the authors of this paper self-identifies as an underrepresented ethnic minority in their field of research or within their geographical location. One or more of the authors of this paper self-identifies as a gender minority in their field of research.

Conflict of Interest

The authors declare no competing interests.

Files

	All versions	This version
Views	0	0
Downloads	0	0
Data volume	0 Bytes	0 Bytes